Motivate Vaccinate Activate: An Effectiveness-Implementation Trial to Assess the Impact of a Multi-Component Community-Based Intervention to Increase RSV Vaccine Uptake Among Latino Older Adults
Phase: NA
Conditions: Older Adults Without Any Specific Clinical Condition, Social Networks, RSV Immunization, Vaccine Uptake
Sponsor: University of California, San Francisco

 
“Motivate Vaccinate Activate” An effectiveness-implementation trial to 
assess the impact of a multi-component community-based intervention to 
increase RSV vaccine uptake among Latino older adults 
 
Protocol Version Number:  3.0 
Protocol Version Date:  August 7, 2025 
NCT Number: pending 
 
Principal Investigator  
Carina Marquez, MD MPH 
 
Study Biostatistician: Dave Graham-Squire, PhD 
 
University of California, San Francisco 
Division of ID, HIV, and Global Medicine, UCSF Box 1272 
UCSF Pride Hall, 2540 23rd St., Floor 4, Rm 4102 
San Francisco, CA  94110 
Phone: 650-636-7131 
San Francisco, CA 94143 
Telephone:  415-476-4082 
E-mail: carina.marquez@ucsf.edu 
 
 
Revision History 
Version 1.2 
Version 2.0 
Version 3.0  
Date 7/27/2024 
Date 5/05/2025 
Date 8/7/2025 
 

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Abstract 
Title 
“Motivate Vaccinate Activate” An effectiveness-implementation trial 
to assess the impact of a multi-component community-based 
intervention to increase Respiratory Syncytial Virus (RSV) vaccine 
uptake among Latino older adults 
Study Description 
Through a community-based participatory research approach this 
study will focus on increasing RSV vaccine uptake among Latinos. In 
two trials we will determine the effectiveness of community health 
worker counseling and text-message interventions to (1) increase RSV 
vaccine uptake among older adults (Motivate trial) and (2) activate 
adults to discuss RSV vaccination with older adults in their social and 
family networks (Activate trial), while also gaining insights into the 
facilitators and barriers of these approaches. 
Study Intervention 
Text message nudges (arm 1) vs. community health worker 
counseling & text message nudge (arm 2) 
Study Population 
(1) Motivate Trial: Latino adults >50 years who are eligible for RSV 
vaccination  
(2) Activate Trial: Latino adults ages 18-49 years 
Primary Objective 
To assess the effectiveness of the ‘Motivate, Vaccinate, Activate’ 
strategy, which includes Community Health Worker (CHW) counseling 
and text-message nudges to  
a.) Increase RSV vaccine uptake among Latino older adults (Motivate 
trial)  
and  
b.) To activate Latino adults to recommend RSV vaccination to older 
adults in their social networks (Activate trial).  
Secondary 
Objectives 
To characterize implementation outcomes of the ‘Motivate, Vaccinate, 
Activate’ strategy, with implementation outcomes defined with the 
Reach, Effectiveness, Adoption, Implementation, Maintenance (RE-
AIM) framework.  
Recruitment 
Methods 
Community-based recruitment in San Francisco, California.  

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Sample Size 
Developmental Aim, Phase 1:  
RSV Vaccine hesitancy survey: 200 adults >18 years and older 
Community Advisory Group: 35 adults >18 years  
Motivate Trial: 400 adults, >50 years 
Activate Trial: 350 adults, 18-49 years 
Duration of Study 
Participation 
Community Advisory Group (6 months) 
Motivate Trial (90 days) 
Activate Trial (90 days)    
Unique Aspects of 
this Study 
This study will address key knowledge gaps surrounding multi-level 
and community-based interventions to improve vaccine uptake among 
Latinos and other racial and ethnic minorities in the United States:  
(1) comparative effectiveness of high vs. low-intensity CHW-led 
interventions, (2) implementation and impact of text-message from 
trusted community-based organizations (CBO), as opposed to health 
systems,(3) effectiveness of cross-generational social network 
strategies, ie. empowering grandchildren to discuss vaccination with 
grandparents,(4) barriers and facilitators to adapting interventions that 
were effective in a pandemic to a non-pandemic setting, where 
urgency and resources are lower. 
 
 

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List of Abbreviations 
 
ADAPT-
ITT 
Assessment, Decision, Adaption, Production, Topical Experts, Integration, 
Training, Testing Framework 
ACIP 
Advisory Council on Immunization Practices 
AE 
ATT 
adverse event 
average treatment effect on the treated 
BeSD 
Behavioral and Social Determinants of Vaccination Framework 
CAIR 
CDC 
California Immunization Registry 
Center for Disease Control  
CHW 
Community Health Worker 
CRF 
case report form 
DSMC 
DSMP  
Data and Safety Monitoring Committee 
Data and Safety Monitoring Plan 
GCP 
Good Clinical Practice 
HIPAA 
Health Insurance Portability and Accountability Act 
ICF 
informed consent form 
ICH 
International Conference on Harmonization 
IDI 
In Depth Interviews  
IRB 
ITT 
Institutional Review Board 
intention to treat 
LTF 
Latino Task Force 
RE-AIM 
Reach, Effectiveness, Adoption, Implementation, Maintenance Framework 
RSV 
TMLE 
Respiratory Syncytial Virus 
Targeted Maximum Likelihood Estimation  
 
 

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Table of Contents 
1.2. Table of Contents 
Abstract 
2 
List of Abbreviations ..................................................................................................... 4 
Table of Contents ......................................................................................................... 5 
1. 
Introduction ........................................................................................................ 7 
1.1. 
Background on RSV Vaccine and Disparities in Vaccine Uptake ...................... 7 
1.2. 
Background on Community-Based Interventions with texting and 
community health workers to Increase Vaccine uptake ................... 8 
1.3. 
Study Rationale ..................................................................................... 10 
2. 
Risk/Benefit Assessment ................................................................................. 11 
2.1. 
Research Procedures Involving Study Subjects .............................. 11 
2.2. 
Potential Risks to Human Subjects .................................................... 11 
2.3. 
Adequacy of Protection Against Risks and Informed Consent ...... 11 
2.3.1. Informed Consent 
11 
2.3.2. Protections Against Risk 
12 
2.3.3. Populations that are vulnerable to coercion or undue influence and 
pregnant women and neonates  
12 
2.3.4. Potential Benefits 
12 
2.3.5. Importance of the Knowledge to be Gained     13 
3. 
Study Objectives and Endpoints ...................................................................... 13 
3.1. 
Primary Objectives ................................................................................ 13 
3.2. 
Secondary Objective(s) .................................................................................... 14 
4. 
Study Design.................................................................................................... 15 
4.1. 
Characteristics ....................................................................................... 15 
4.1.1. Study Setting 
16 
4.2. 
Study Design for Developmental Aim 1 ............................................ 17 
4.2.1. Overview of Aim 1 (Figure 1) 17 
4.2.2. Aim 1 Duration 19 
4.2.3. Aim 1 Sample Size 
19 
4.3. 
Study Design of Aim 2-Motivate Trial ................................................ 19 
4.3.1. Introduction and Rationale to Aim 2 19 
4.3.2. Study Population 
20 
4.3.3. Study Design and Description of Intervention Groups 
20 
4.3.4. Location of interventions and survey procedures 
21 
4.3.5. Duration of study procedures 21 
4.4. 
Study Design of Aim 3 – Activate Trial .............................................. 21 
4.4.1. Introduction and Rationale: 
21 
4.4.2. Study Population 
22 
4.4.3. Study Design Aim 3 and Intervention Groups 
22 
4.4.4. Location of CHW interventions and survey procedures 
22 
4.4.5. Duration of study intervention 22 

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Table of Contents 
4.5. 
Primary Completion .............................................................................. 22 
4.6. 
Study Completion .................................................................................. 22 
5. 
Selection and Enrollment of Participants ......................................................... 23 
5.1. 
Eligibility Criteria .................................................................................... 23 
5.1.1. Inclusion Criteria and Exclusion Criteria 
23 
5.2. 
Recruitment Methods for Aims 1-3..................................................... 24 
5.2.1. Recruitment 
24 
5.2.2. Participant Incentives 25 
5.3. 
Inclusion of Women and Minorities .................................................... 25 
5.3.1. Recruitment of Women and Minorities 
25 
5.4. 
Inclusion Across the Lifespan ............................................................. 25 
5.5. 
Participant Registration ........................................................................ 26 
6. 
Study Intervention and Randomizations .......................................................... 26 
6.1. 
Randomization (Aim 2 & 3) ................................................................. 26 
6.2. 
Interventionist Training, Tracking and Fidelity .................................. 26 
6.3. 
Participant Discontinuation/Withdrawal from the Study .................. 27 
6.4. 
Lost to Follow-up ................................................................................... 27 
7. 
Study Procedures and Assessments ............................................................... 27 
7.1. 
Informed Consent and Enrollment ..................................................... 27 
7.2. 
Randomization and Interventions for Trials ...................................... 28 
7.2.1. Randomization and Interventions for ‘Motivate’ Trial (Aim 2) 
28 
7.2.2. Randomization and Interventions for ‘Activate’ Trial (Aim 3) 
30 
7.3. 
Schedule of Activities (Aim 2 and 3) .................................................. 32 
8. 
Reporting of Adverse Events ........................................................................... 33 
9. 
Statistical Considerations ................................................................................. 33 
9.1. 
Aim 1 Statistical Considerations ......................................................... 34 
9.2. 
Aim 2 (Motivate Trial) Statistical Considerations ............................. 34 
9.2.1. Aim 2 Sample Size Considerations 
34 
9.3. 
Aim 3 (Activate Trial) Analysis Plan ................................................... 35 
9.3.1. Aim 3 Sample size considerations 
35 
9.3.2. Randomization and Blinding 
36 
9.3.3. Stratification Factors 
36 
10. 
Study Management .......................................................................................... 36 
10.1. 
Pre-study Documentation .................................................................... 36 
10.2. 
Institutional Review Board Approval .................................................. 36 
10.3. 
Changes in the Protocol ...................................................................... 36 
10.4. 
Publications ............................................................................................ 36 
11. 
References....................................................................................................... 37 
 
 

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1. Introduction 
1.1.     Background on RSV Vaccine and Disparities in Vaccine Uptake  
The new and effective Respiratory Syncytial Virus (RSV) vaccines have the potential to 
reduce the large burden of RSV disease in older adults—which causes an estimated 12,700 
deaths,160,000 hospitalizations, 1.4 million outpatient visits per year.1,2 Yet, their full public 
health impact will not be realized if we allow the racial and ethnic disparities in RSV vaccine 
uptake to mirror those observed in other respiratory virus-vaccines, from COVID-19 to 
influenza.3–5 Nationally representative data6 already demonstrate disparities in RSV vaccine 
confidence by race/ethnicity and income. Among older adults, Latinos have lower RSV vaccine 
confidence compared to non-Latino White people. The time is now to proactively generate the 
rigorous data needed to inform efficient and equitable interventions to increase uptake of this 
new vaccine. 
Respiratory Syncytial Virus (RSV) causes a substantial burden of hospitalizations and 
deaths among older adults, with a disease burden similar to influenza.1,2,7–10 RSV is a 
seasonal respiratory virus that can cause severe lower respiratory tract infections and 
pneumonia in young children and older adults, especially those with other co-morbid health 
conditions. Morbidity due to RSV is high, it causes an estimated 12,700 deaths, 159,000 
hospitalizations, 119,000 emergency room visits and over 1.4 million outpatient visits per year 
among older adults living in the US.2,11 A cohort study in older adults highlights the high 
incidence of RSV, with 5.5% in the cohort infected annually, nearly twice that of the flu.2 The 
burden of RSV goes beyond hospitalization; older adults who are infected with RSV are more 
likely to have role limitation and decreased social functioning.8,10 RSV disproportionately affects 
racial and ethnic minorities, hospitalizations due to RSV were 7.8 per 100,000, compared to 4.4 
per 100,000 among non-Latino white individuals.1 These disparities by race/ethnicity are seen 
broadly among acute respiratory viral infections in older adults.7,12–14 We now have a new 
preventive tool to decrease this large burden of disease. The new RSV vaccines, approved in 
2023, are highly effective (89%15 and 83%16 effective against symptomatic infection) and can 
have a large public health impact on morbidity and mortality in older adults. However, timely 
evidenced-based data is needed to guide interventions for an equitable RSV vaccine uptake. 
In 2025 the Centers for Disease Control (CDC) and the Advisory Committee on 
Immunization Practices (ACIP) updated their recommendations and all adults 50 years 
older are eligible for one dose of the RSV vaccine. They also uniformly recommend one 
RSV vaccination for (1) adults 75 years and older and (2) adults 50-74 years old who have an 
increased risk of severe RSV disease. Persons who are considered at increased risk for RSV 
are those with: cardiovascular disease (e.g hypertension, coronary artery disease), lung disease 
(e.g COPD, asthma), advanced chronic kidney disease, diabetes, liver disorders, neurologic or 
neuromuscular conditions, hematologic disorders, moderate or severe immune compromise, 
frailty, people who reside in nursing homes, people with chronic medical conditions or risk 
factors that a healthcare provider determines might increase risk of severe disease due to 
respiratory infections.  
Vaccine hesitancy is a major threat to the equitable uptake of the new Respiratory 
Syncytial Virus (RSV) vaccines. Since the introduction of the new RSV vaccine for older 
adults in 2023, uptake has been low, and significant disparities have already emerged. 

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According the CDC, as of May 2024, only 24% of adults over the age of 60 have received the 
vaccine, with uptake differing by race-ethnicity (14.5% among non-Latino, 20.7% Black, 26.5% 
non-Latino White), insurance status (7.7% uninsured vs. 25% insured) status, and income level 
(15.5% for people below the national poverty level vs. 27.9% for those above the national 
poverty level).17 Multi-level, community-based interventions are needed to address the three 
components of RSV vaccine hesitancy: confidence in the safety and efficacy of the vaccine, 
complacency towards vaccine uptake, confidence in the safety and efficacy of this new vaccine, 
and convenience in accessing the vaccine.18  
1.2. 
Background on Community-Based Interventions with texting and 
community health workers to Increase Vaccine uptake 
Latino older adults, especially immigrants, experience unique barriers and facilitators to 
vaccine uptake and tailored strategies are needed. Studies specific to vaccine hesitancy in 
older adults highlight the importance of knowledge about vaccine eligibility, access, vaccine 
safety, and health beliefs about susceptibility of infection.19,20 While these barriers by are shared 
across different race-ethnicity, Latino older adults face additional barriers, including lack of 
language concordant vaccine information, experiences of racial discrimination,21–23 mistrust of 
government and health institutions—often rooted in systemic racism and hostility to 
immigrants,24–26 and health-care access related barriers (e.g transport, insurance). Facilitators 
include trust in community-based organizations and health care providers for vaccine 
information, low-barrier language concordant vaccine sites, and familial and social 
influences.24,26,27  
 
The COVID-19 vaccine roll-out triggered a renaissance of community-based approaches 
to increase vaccine uptake among Latinos and other historically marginalized 
communities. COVID-19 vaccination strategies that move vaccination outside of brick-and 
mortar health care institutions to trusted community spaces, in-partnership with the impacted 
community, have been successful at reducing racial/ethnic disparities.24,28 Successful examples 
include vaccine promotion by community health workers and vaccination at trusted community 
sites (e.g., barber shops, churches, and health fairs) coupled with culturally concordant 
messaging about vaccine eligibility, safety, and efficacy.24,28,29 This success is due to multi-level 
interventions that address both access and trust-related barriers. While much has been learned 
about improving vaccine uptake during the COVID-19 pandemic, new data is needed to guide 
efficient and equitable adaptations of vaccinations in the post-pandemic era, where urgency for 
vaccination and resources for community-based organizations is decreasing. 
 
Our Unidos en Salud multi-component ‘Motivate, Vaccinate, Activate’ model is feasible 
and effective, and we have the opportunity to adapt it to RSV vaccination. The Unidos en 
Salud Collaboration,30 a community-academic partnership between UCSF and the San 
Francisco Latino Task Force (Figure 1), co-designed and evaluated this strategy.31 It includes 
three components: (1) Motivate: community mobilization and demand generation by CHWs, 
(2)Vaccinate: a low barrier vaccine site centrally located in the Latino cultural hub of San 
Francisco, staffed by trusted, welcoming, Spanish-speaking CHWs that does not ask for ID or 
insurance, (3)Activate: CHWs encouraged clients to reach out to members of their social 
networks who have not been vaccinated. We evaluated the implementation of this multi-
component intervention among 11,098 individuals accessing our vaccine site and we found that 

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the intervention was effective, feasible, and reached our priority population of low-income Latino 
immigrants.31 Among Latino clients, 76% had an annual household income of less than 
$50,000, 60% were first-generation immigrants, and 47% did not have access to primary health 
care services. Effectiveness measures focused on behavioral change: 58% of clients of 
clients stated that they were able to get vaccinated more quickly due to the vaccine site, 
90% said they were more likely to recommend vaccination to their family members and 
friends, and 83% reported recommending the vaccine to 1 or more people in their 
network. The model was highly acceptable and feasible, and participants attributed trust and 
convenience as the top reasons Established community-academic partnerships, such as Unidos 
en Salud, can efficiently adapt strategies to promote COVID-19 vaccine uptake to RSV, while 
centering the priority community.  
Community Health Workers (CHWs) played a crucial role in increasing COVID-19 
vaccination. Shared language and life experiences allow CHWs to quickly establish trust. To 
our knowledge, there are no randomized studies on the direct impact of CHWs alone on vaccine 
uptake in the United States, though cross-sectional implementation-focused studies identity the 
importance of CHWs as part of multi-component vaccination strategies.31,32 To our knowledge 
there is only one randomized study on a counseling intervention by peer vaccine ambassadors. 
This study included a large Latino population who inject drugs and found that a peer education 
and navigation intervention, designed to address both hesitancy and access related barriers, 
increased COVID-19 vaccine uptake by 35%33.Outside of vaccinations, there is a large body of 
literature to support the importance of CHW education to increase uptake of preventative health 
services, especially with of cancer screening.16,34,35 Despite the large body of knowledge about 
CHWs, key scientific knowledge gaps remain about the relative effectiveness high-intensity 
CHW counseling sessions vs. lower-intensity ‘outreach’, and few studies assess the impact of 
CHWs on activating vaccine uptake in social networks. 
Behavioral nudges with text messages can increase vaccine uptake. In behavioral 
economics, nudges are small interventions or alterations in the environment that make it more 
likely that an individual will make a particular (preferred) choice. A text message nudge can 
address two barriers. First, it serves as a prompt to make the recipient aware a vaccination is 
due and to follow through on vaccination intentions. Second, it can provide information about 
how and where to schedule appointments. Text messages interventions from large health 
systems have demonstrated success for flu vaccination36, childhood vaccines37 and COVID-
1937,38, with a boost in vaccination by 4%-8%. Latinos, especially those who are uninsured, are 
largely left out of these studies, for example, in a large text-message study in a health system in 
Los Angeles, Latinos comprised only 10% of the study population despite being 48.6% of the 
population. While text messaging reminders are a promising intervention, we need to improve 
the reach of this tool to patients who are uninsured or not on digital health system portals. To 
date, aside from our preliminary data, there are no studies focusing on text messaging 
interventions with texts originating from community-based organizations.  
Social networks can exert positive influences on vaccine uptake. Social contagion theory 
describes the process whereby a person adopts the health behaviors or attitudes of their social 
network39 A scoping review on social networks and vaccination highlight three main areas of 
influence that motivate our proposed work40: (1) Individuals were more likely to have a positive 
attitude to vaccination and higher uptake if their friends or family held positive beliefs about 
vaccination (2) Individuals were more likely to get vaccinated or perceive a vaccine as effective 

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if they heard about or discussed vaccinations with peers. For example, Latina women were 4.7 
x higher odds of perceiving the HPV vaccine as effective if they heard about the vaccine from 
friends41. (3) Shared race/ethnicity was high in social networks and racial/ethnic concordance. 
Data from our ‘Motivate, Vaccinate, Activate’ intervention showed a positive impact of a CHW 
intervention on recommending COVID-19 vaccination to family or friends. Given the large 
amount of cross-sectional formative data on the influence of social networks on vaccine uptake, 
now is the time for randomized trials on the impact of community-based interventions to 
increase vaccine uptake across social networks, including cross-generational networks. 
A growing body of evidence suggests younger people can influence the health behaviors 
of older family members. In a vaccine uptake study from the United Kindom,42 35% of older 
people said that younger relatives pass on health messages to the, and this proportion was 
higher (55%) among racial and ethnic minorities compared to White people. Among older 
adults, at least 22% overall, compared to 44% of Black participants, said that recommendations 
from younger people influenced their health behaviors. Younger people report that knowledge 
gaps about vaccine safety and eligibility were the main barriers to recommending vaccination to 
older family members. The proposed study will measure the effectiveness of a CHW and text-
message intervention to enable people to discuss RSV vaccines to older persons in their social 
network. 
1.3. 
Study Rationale 
Respiratory Syncytial Virus (RSV) causes a substantial burden of hospitalizations and deaths 
among older adults, comparable to that of influenza. The new and effective RSV vaccines have 
the potential to dramatically reduce RSV morbidity and mortality, yet their full public health 
impact will not be realized if the racial and ethnic disparities in RSV vaccine uptake mirror those 
observed in other respiratory virus-vaccines, from COVID-19 to influenza. We have the 
opportunity to adapt community-based interventions from the COVID-19 pandemic to 
proactively address disparities in RSV vaccine uptake. However, evidence-based data, 
conducted in partnership with impacted communities, are essential.  
This project focuses on increasing RSV vaccine uptake among Latinos, a community 
disproportionately affected by respiratory vaccines and RSV. We will leverage our well-
established community-academic partnership, Unidos en Salud, to adapt two components of our 
‘Motivate, Vaccinate, Activate’ intervention—CHW counseling and text message nudges. This 
multi-component intervention was originally designed to increase COVID-19 vaccine uptake 
among Latinos and to activate people to recommend vaccination to people in one’s social 
network. Our overall study objective is to adapt this intervention to inform effective and 
customizable community-based strategies to increase RSV vaccine uptake. In addition to a 
rigorous randomized trial design, we will collect detailed implementation outcomes to aide in 
generalizability and adaption to other vaccines and settings. 
This study will provide timely, rigorous, and adaptable data to directly inform community-based 
approaches to increase RSV vaccination. In addition to providing timely data to reduce RSV 
vaccine disparities, these data will address key knowledge gaps surrounding multi-level 
interventions to improve vaccine uptake: (1) comparative effectiveness of high vs. low-intensity 
CHW-led interventions, (2) implementation and impact of text-message from trusted community-
based organizations (CBO), as opposed to health systems, (3) effectiveness of cross-
generational social network strategies, ie. empowering grandchildren to discuss vaccination with 

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grandparents, (4) barriers and facilitators to adapting interventions that were effective in a 
pandemic to a non-pandemic setting, where urgency and resources are lower. Our overall 
objective is to inform effective and customizable community-based strategies to increase RSV 
vaccine uptake among Latino older adults, with generalizability to other settings.  
2. Risk/Benefit Assessment 
2.1. 
 Research Procedures Involving Study Subjects 
Recruitment: Latino Task Force/Unidos en Salud Community Health Workers (CHWs) in 
partnership with bilingual bicultural UCSF study staff will recruit eligible participants among 
people who are receiving services or attending community cultural or health fairs at Latino Task 
Force (LTF) sites or CBOs affiliated with the Latino Task Force.  
 
CHW Counseling: Participants in Aim 2 and Aim 3 will have a 20-minute counseling session 
with a community health worker. The content of the session will consist of the 5A’s technique 
and will be informed by adaptations made in Aim 1.  
 
Text-message nudge: Participants will receive a text message about RSV vaccination with a 
scheduling and informational link. The text-message will be sent on behalf of the Latino Task 
Force.  
 
Questionnaires: At baseline and endline participants will complete a survey on demographics, 
vaccine confidence, hesitancy, and social networks. Names will not be collected in the social-
network survey.  
 
2.2. 
Potential Risks to Human Subjects 
There are relatively few risks to study participants of study participation and include: i) 
inadvertent disclosure of health information, including past medical history; and ii) psychological 
stress during interview procedures.  
2.3. 
Adequacy of Protection Against Risks and Informed Consent  
2.3.1. 
Informed Consent  
Consenting will be performed in the native or requested language of the participant, Spanish or 
English. We will seek informed consent either in person or through remote consent with 
DocuSign from all participants. After the participant has read the consent form, prior to seeking 
a signature, study staff will ask participants to summarize the study and explain the reasons why 
they want to participate. Any misunderstandings regarding procedures, risks, or benefits will be 
clarified. Individuals will be provided with information on how to contact the study staff to report 
adverse events. Study staff will be trained in the need to ensure that individuals provide 
voluntary informed consent. For adults who are illiterate, witnesses independent from the study 
will be required to be present for the consent discussion and to co-sign consent forms upon 
confirming that the participant’s consent is given voluntarily and freely. Illiterate participants may 
mark an X on the signature line if they cannot sign themselves and the witness will provide the 
date next to the participant’s signature line. 
 
Study staff will document informed consent for each participant. Participants may withdraw 
consent at any time. 

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2.3.2. 
Protections Against Risk 
Privacy: Surveys will be conducted either by staff administering them in a private location at 
LTF- affiliated CBOs or if preferred over the phone. In-depth interviews will occur at Mission 
Language Vocational School, UCSF or remotely via the online meeting platform Zoom or phone 
(if preferred). Community Advisory Groups will occur at Mission Language Vocational School in 
a private room or over Zoom.   
 
Data Security: Study staff will collect all field electronic data on password encrypted devices. 
Any paper data collection forms, if necessary, will be data entered into a digital form, with paper 
forms stored in secure, locked offices at UCSF. Data will be stored in a secure cloud or on 
encrypted computers. For data collected as part of the study, participants will be assigned a 
unique identification number, and paper or electronic documentation that includes identifiers will 
be minimized. All study staff will be trained on procedures for maintaining confidentiality and 
undergo human subjects protection training.  
 
2.3.3. 
Populations that are vulnerable to coercion or undue influence and 
pregnant women and neonates 
Reimbursements for participation are calibrated to avoid undue coercion for participation, and 
most participants are unlikely to experience a significant economic gain as a result of 
participation.  A publication by a research group (the Ethics Working Group of the HIV 
Prevention Trials Network) has also made the case that the use of incentives for health 
promotion does not necessarily undermine individual autonomy Instead, the incentives can help 
overcome economic obstacles or motivational deficiencies; they can promote engagement in 
health-related behaviors that participants regard as beneficial or worthwhile, but do not 
undertake due to behavioral biases such as present-biased preferences. 
 
To minimize the likelihood of persons feeling pressured to participate in research we will 
emphasize the concepts of individual voluntary choice to participate in research and the need 
for study staff to respect the voluntary choice of others during the process of obtaining informed 
consent from adults and their children. Study participants will also be informed that participation 
can be stopped at any point during the study at their request.  
 
2.3.4. 
Potential Benefits 
Study participants may benefit by learning about RSV vaccination, eligibility, and navigation to 
vaccination.  The benefits for the community may include adapted strategies to increase vaccine 
uptake in a community disproportionately impacted by respiratory viruses and with historically 
lower rates of vaccine uptake compared to non-Latino White populations. 
 
The minimal risks to subjects are reasonable in comparison to the potential benefits to 
themselves and their community by improving RSV vaccine uptake. The RSV vaccine is FDA-
approved and we will only enroll participants who are eligible for RSV vaccination per the CDC 
and ACIP.  
 

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2.3.5. 
Importance of the Knowledge to be Gained 
The minimal risk in this study is far outweighed by the importance of the knowledge to be 
gained. The overall objective of the study is to inform effective, actionable, and customizable 
community-based strategies to increase RSV vaccine uptake among Latino older adults, with 
generalizability to other vaccines and settings. Findings from this study will fill key knowledge 
gaps about vaccine promotion in communities that experience health disparities: (1) 
effectiveness of high vs. low-intensity CHW counseling interventions, (2) implementation and 
impact of text-message from trusted community-based organizations, as opposed to health 
systems, (3) effectiveness of cross-generational social network strategies, ie. empowering 
grandchildren to discuss vaccines with grandparents, (5) facilitators and barriers to adapting 
interventions that were effective in a pandemic to the non-pandemic setting, where urgency and 
resources are lower. 
3. Study Objectives and Endpoints 
3.1. 
Primary Objectives 
Our overall study objective is to assess the effectiveness and implementation of the 
Unidos en Salud (UES) ‘Motivate, Vaccinate, Activate’ strategy, which includes CHW counseling 
and text-messaging on increasing RSV vaccine uptake among older Latino adults. Our 
primary hypothesis is that language- and culturally-concordant CHW motivation and activation 
counseling sessions, coupled with text message nudges, will increase RSV vaccine confidence 
by addressing trust, knowledge, and access-related barriers. To achieve this objective, we will 
first adapt the key intervention components in Aim 1, then will determine the effectiveness of a 
multicomponent intervention (CHW counseling and text-message nudges) on increasing 
vaccine uptake in Latino older adults (Aim 2) and encouraging Latino adults (18-49 years) to 
discuss RSV vaccination among older adults in their family and social networks (Aim 3). The 
primary outcomes are summarized in Table 1.  
 
The Study Aims are:  
Aim 1: Adapt a CHW counseling and text-message intervention to increase RSV vaccine 
uptake and activate younger adults to discuss RSV vaccination with older adults in their 
social networks. In his developmental aim, we will use the ADAPT-ITT framework43 to adapt 
two intervention components CHW counseling and text-messages nudges, to increase RSV 
vaccine uptake in Latino older adults (>50 years)  
Aim 2: Determine the effectiveness of CHW counseling and text-message nudges from a 
CBO on RSV vaccine uptake among Latino older adults. In a randomized two-arm trial, will 
compare CHW counseling and text message nudges vs. CHW delivered RSV vaccine flyer + 
text-message nudges in 400 Latino adults >50 years. Study interventions are adapted in Aim 
1a. Our hypothesis is text messages coupled with a community health worker counseling 
session will increase RSV vaccine uptake compared to texts alone. Primary Outcome: RSV 
vaccine uptake at 60 days. Secondary outcomes include change in motivation to get and 
confidence in the RSV vaccine,  implementation per the RE-AIM framework44, with a focus on 
implementation, adoption and maintenance assessed via mixed methods. 
 
Aim 3: Determine the effectiveness of CHW ‘activation’ counseling and text-message 
nudges from a CBO on activating adults to discuss RSV vaccination with older adults in 
their social network. In a parallel design to Aim 2, we will compare: CHW ‘activation’ 
counseling and text message nudges vs. RSV vaccine flyer at enrollment + text-message 
nudges in 350 Latino adults (18-49 years). Study interventions will be adapted in Aim 1b. Our 

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hypothesis is text messages coupled with CHW counseling will activate participants to discuss 
RSV vaccination with older adults in their network, compared to text-message alone. Our 
primary outcome is average proportion of older adult (>50 years old) network contacts with 
whom RSV vaccination was discussed. Secondary outcomes include change in knowledge 
about the RSV virus and the vaccine, change in motivation to discuss the RSV vaccine with 
eligible family members or friends, implementation per the RE-AIM framework, with a focus on 
implementation, adoption, and maintenance components assessed via mixed methods 
 
 
 
3.2.   Secondary Objective(s) 
Aim 1 (Development aim).  
• 
Secondary: Predictors of RSV Vaccine hesitancy, Adaptation of text-message and CHW 
counseling intervention with Community Advisory Board.  
Aim 2: 
Secondary: 
• 
RSV Vaccine uptake at 60 days (self-report) 
• 
RSV Vaccine uptake at 90 days per CAIR or per medical record 
• 
RSV Vaccine uptake at 6 months per CAIR or per medical record 
• 
Median time to vaccination (days)  
• 
Appointment made at 60 days in clinic or a pharmacy with intent to get RSV Vaccine per 
self-report 
• 
Increase in RSV Vaccine confidence (BeSD indicator) by 1 point  
Primary Objective 
Endpoint(s) 
Time Frame 
1. Aim 1 (Developmental Aim) 
-Community-based survey on RSV 
vaccine hesitancy 
-Community advisory group adapts 
intervention components. 
-In depth interviews 
N/A 
1 year  
2. Aim 2 (Motivate Trial): Determine 
the effectiveness of CHW 
counseling and text-message 
nudges from a CBO on RSV 
vaccine uptake among Latino older 
adults. 
RSV Vaccine uptake at 60 
days per California 
Immunization Registry 
(CAIR) or per medical record 
 
60 days from time of 
intervention 
3. Aim 3 (Activate Trial): Determine 
the effectiveness of CHW 
‘activation’ counseling and text-
message nudges from a CBO on 
activating adults to discuss RSV 
vaccination with older adults in their 
social network. 
Self-reported average 
proportion of social network 
contacts >50 years with 
whom participant discussed 
RSV vaccination at 60 days.  
 
60 days from time of 
intervention 
Table 1: Primary Objectives 

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• 
Increase in motivation to get RSV Vaccine (BeSD indicator) by 1 point  
• 
Increase in RSV vaccine knowledge by 1 point (Likert scale): Before today how much did 
you know about the RSV vaccine (1 = nothing, 2= a little, 3= some, 4= a lot) 
• 
Average proportion of social network contacts >50 years with whom participant discussed 
RSV vaccination at 60 days.  
• 
Implementation outcomes per Reach Effectiveness Adoption Implementation Maintenance 
(RE-AIM) framework (Table 2) 
 Aim 3: 
Secondary:  
• 
Discussed RSV vaccination with 
>1 eligible family member or 
friend within 60 days of 
enrollment  
• 
Implementation outcomes per 
Reach Effectiveness Adoption 
Implementation Maintenance 
(RE-AIM) framework (Table 2)  
• 
Increase in RSV Vaccine 
confidence (BeSD indicator) by 1 
point  
• 
Increase in motivation to discuss 
the RSV Vaccine with eligible 
family members or friends(BeSD 
indicator) by 1 point  
• 
Increase in confidence in the 
RSV Vaccine (BeSD indicator) by 
1 point  
• 
Increase in RSV vaccine 
knowledge by 1 point (Likert 
scale): Before today how much 
did you know about the RSV 
vaccine (1 = nothing, 2= a little, 
3= some, 4= a lot) 
 
4. Study Design 
4.1. 
Characteristics 
Study Overview. In this type 1 hybrid-implementation study we will leverage our well-
established UES collaboration, a community-academic partnership. We will uphold community-
based participatory research principles throughout the study.45 In Aim 1, a developmental aim, 
we will use the ADAPT-ITT framework to adapt two intervention components, CHW counseling 
and text-messages nudges from a CBO, to increase RSV vaccine uptake in Latino older adults 
(>50 years) who are eligible for RSV vaccination (Aim 1a) and to activate Latino adults (18-49 
years) to discuss RSV vaccination with older adults in their family and social network (Aim 1b). 
Table 2: RE-AIM Outcomes for Motiviate and Activate Trials 

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We will also conduct a community-based anonymous survey to assess knowledge and 
perceptions about RSV and RSV vaccine knowledge. Then, in Aim 2 (Motivate Trial), we will 
randomize 400 Latino older adults to CHW counseling and text message nudges vs. CHW 
delivered RSV vaccine information flyer at enrollment + text-message nudges, all adapted in 
Aim 1a. The primary outcome in Aim 2 is RSV vaccine uptake. In Aim 3 (Activate trial), using a 
parallel design we will randomize 350 Latino adults (18-49 years) to CHW ‘activation’ counseling 
to encourage them to discuss RSV vaccine with people over 50 and older in their network and 
text-message nudges vs. RSV vaccine information flyer at enrollment + text-message nudges, 
all adapted in Aim 1b. The primary outcome for Aim 3 is average proportion of older adults in 
participants’ social network with whom they discussed RSV vaccination. We will incorporate 
implementation outcomes as secondary outcomes, which we will evaluate using the Reach, 
Effectiveness, Adoption, Implementation and Maintenance (RE-AIM) framework,44,46 an 
integrated framework to improve adoption and sustainable implementation of interventions and 
includes an explicit focus on equity to address dynamic implementation contexts. Our overall 
study design is in line with a type-1 hybrid effectiveness-implementation trial,47 which tests an 
intervention effectiveness as a primary aim, while gathering information on its delivery or 
implementation in the real-world.  Table 3 provides an overview of the overall study design and 
primary outcomes.  
 
 
4.1.1. 
Study Setting 
This study will take place in San Francisco at Latino Task Force (LTF)-affiliated community sites 
and will leverage the existing infrastructure and reach of the Unidos en Salud collaboration, a 
community academic partnership between the Latino Task Force and UCSF.  The Latino Task 
Table 3: Study Overview  

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force is a coalition of over 30 Latino focused CBOs and based at the Mission Language 
Vocational School (MLVS), a CBO in San Francisco’s Mission District.  
 
4.2. 
Study Design for Developmental Aim 1 
The overall objective of Aim 1 is to adapt the ‘Motivate, Vaccinate, Activate’ CHW counseling 
and text-message intervention to increase RSV vaccine uptake and to activate younger adults 
to discuss RSV vaccination with older adults in their social networks.  
 
4.2.1. 
Overview of Aim 1 (Figure 1) 
 
 
In this 
developmental aim, 
we will use the 
ADAPT-ITT43  
(Figure 2) 
implementation 
science framework 
to adapt two core 
intervention 
components from 
our Motivate, 
Vaccinate Activate 
Strategy (CHW 
vaccine counseling 
and text-message 
nudges) to promote 
RSV vaccine 
uptake among 
Latino older adults 
(>50 years) (Aim 1.1) and activate adults (18-49 years old) to discuss RSV vaccination with 
older adults in their social and family networks (Aim 1.2). In Figure 2 we outline the ADAPT-ITT 
process.  As part of the Assessment phase of ADAPT-ITT we will (1) administer an anonymous 
community-based survey adults 18 years and older on knowledge and perceptions about RSV 
and RSV vaccination for Aim 1 and (2) Conduct In depth Interviews (3) Community advisory 
board meetings using the ADAPT-ITT process to assess perceptions of RSV Vaccination and 
preferences for intervention components and knowledge and attitudes about RSV Vaccination. 
The ADAPT-ITT framework was designed to assist CBOs in adapting evidence-based 
interventions to fit new populations.  
 
 
 
 
 
Figure 1: Overview of Aim 1 

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While our Unidos en Salud ‘Motivate, Vaccinate, Activate’ strategy is acceptable, feasible and 
effective for COIVD-19 vaccine uptake among Latinos, the core-components need adaptations 
for a different vaccine and infection (RSV), a non-pandemic setting, and different age-groups.  
We will use the Behavioral and Social Determinants (BeSD) of vaccination framework and 
core questions48,49 for developing and coding our interview guides and to examine potential 
mediators of the effect of our interventions. The BeSD framework is informed by multiple  
theoretical models: COM-B, 3C’s50, socio-ecological model, and the Increasing Vaccination 
Model51  and identifies 2 domains, ‘thinking and feeling’ and ‘social processes’ , as most 
associated with lack of vaccine confidence ‘motivational conflict’, and a fourth domain ‘practical 
issues’ as a domain that moderates the relationship between lack of vaccine confidence. In 
Figure 3 we present an adapted BeSD framework, which highlights intersections with our 
‘Motivate, Vaccinate, Activate intervention and highlights integration of the 3C’s from the SAGE 
working group.18,52.   
Figure 2 

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4.2.2. 
Aim 1 Duration  
a. Community-based survey on RSV Knowledge and Vaccine Confidence: Cross-sectional 
survey, which will last up to 25 minutes for 1 study visit.  
b. Community Advisory Boards Meetings for ADAPT-ITT: Community Advisory Board 
members will participate in 3-5 design sessions. The anticipated duration of involvement 
will be 12 months. 
c. In Depth Interviews: In-depth interviews on RSV vaccine confidence and preferences on 
text messaging and CHW counseling sessions for Aim 2 and 3.  CAB members can 
participate in IDIs.  
4.2.3. 
Aim 1 Sample Size  
Aim 1 is a developmental Aim. Sample size is extrapolated for standard sample sizes needed 
for the ADAPT-ITT framework and to reach saturation for In Depth Interviews (IDIs). 
4.3. 
Study Design of Aim 2-Motivate Trial 
4.3.1. 
Introduction and Rationale to Aim 2 
Drawing on our ‘Motivate, Vaccinate, Activate’ multi-component strategy and adaptations for 
RSV vaccination from Aim 1a, we will rigorously evaluate the effectiveness of a multi-
component CHW counseling session and CBO text-message intervention compared to text 
alone (Figure 4). Our primary Hypothesis is that text messages coupled with a community 
health worker counseling session will increase RSV vaccine uptake compared to text-message 
alone. We hypothesize that the CHW counseling session will improve trust in the vaccine ability 
to navigate access-related barriers, and that this intent to vaccinate is reinforced by a text-
message from a trusted source. 
Understanding if there is an additional benefit to the more time-intensive CHW counseling will 
provide the evidence needed for CBOs and public health departments to design community-
based RSV vaccination strategies for Latinos. We have chosen to not have a ‘standard of care 
arm’, but instead will compare the multi-component intervention to text-messages for three 
reasons: (1) Text-messaging interventions are low-cost intervention, which are effective in our 
Figure 3 

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preliminary data (2) given the moderate anticipated effect size, power to detect benefit of adding 
text to the CHW intervention would require a 
sample size too large to be feasible given the 
intensity of the CHW intervention, 
and (3) we have modeled Arm 1 to 
mirror a ‘lower intensity’ CHW 
intervention akin to CHW outreach, 
with CHWs handing out an 
informational flyer at enrollment and 
receipt of a text message nudge.  
4.3.2. 
Study Population 
CHWs and study staff will recruit 
from people accessing services or 
community fairs at LTF-affiliated 
CBOs in San Francisco. Study 
inclusion criteria include adults 50 
and over who are eligible for the 
RSV Vaccine; detailed inclusion 
criteria are outlined in section 5.1.1.  
4.3.3. 
Study Design and 
Description of Intervention Groups 
This is a two-arm randomized type-1 effectiveness-implementation individually randomized trial 
(Figure 4), with study groups: 
i) Arm 1- Text message nudge from CBO: Participants will receive an educational flyer from a 
CHW about RSV vaccination and how to schedule it. Then 4 weeks after enrollment they will 
receive a text-message nudge, with message content based on findings in Aim 1a. This text 
message will also provide a flyer with vaccine information and eligibility. A phone number to the 
CHW team, the LTF hotline, for help with navigation will be provided on the flyer and in the text-
message. 
ii) Arm 2: CHW counseling and text message nudge from a CBO: At enrollment, participants 
will receive an educational flyer from a CHW, as in Arm 1, and will set up a time for the CHW 
counseling session. They can select remote (phone or web-based platform such as Zoom) or in-
person counseling within 2 weeks of enrollment, and weekend hours will be offered. CHW 
counseling will consist of a 20-minute semi-scripted conversation grounded in the motivational 
interviewing principals of Five A’s53 and adapted in Aim 1a. CHWs will assess participants 
beliefs and knowledge about RSV susceptibility and vaccine effectiveness, safety, and eligibility. 
They will advise and provide general information on vaccine eligibility and RSV susceptibility. 
Then, assist by assessing personal or structural barriers to vaccination and providing problem-
solving techniques. Then arrange next steps: for navigation to a vaccine provider or interest in a 
follow-up call. CHWs will write down an action plan and give it to the participant, e.g. call clinic 
to make vaccine appointment in 5 days or follow-up call with CHW in 1 week. CHWs can 
provide general education about the vaccines: safety, eligibility, testimonials, but they will refer 
Figure 4: Schema of Aim 2 ‘Motivate Trial’ 

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individual medical questions to the participant’s physician. CHWs will also provide a hotline for 
any questions or assistance with navigating health and vaccine linkage for participants.  
4.3.4. 
Location of interventions and survey procedures  
The CHW counseling and baseline survey will be done via phone, Zoom or in person at the 
Mission Language Vocational School (Latino Task Force headquarters), ZSFG Clinical 
Research Center or in private locations in LTF-affiliated community venues. Endpoint follow-up 
can be done in-person in the same locations as the baseline visit or over the phone or Zoom, 
with survey completion done remotely using REDCap.  
4.3.5. 
Duration of study procedures 
The duration of study procedures is 90 days, but participants can be in the study up to 24 
months from enrollment if they are selected for in-depth interviews.  
4.4. 
Study Design of Aim 3 – Activate Trial 
4.4.1. 
Introduction and Rationale:  
The objective of Aim 3 is to determine the effectiveness of CHW ‘activation’ counseling and text-
message nudges from a CBO on activating adults to discuss RSV vaccination with older adults 
in their social network.  
In a parallel structure to Aim 2 we will conduct a randomized trial (Figure 5) of the intervention 
components (CHW counseling and text-message from a CBO) adapted in Aim 1.2. 
Recommending vaccination not only requires confidence in the vaccine and knowledge about 
eligibility, but also capability and opportunity to 
initiate the conversation. We hypothesize that 
text messages coupled with a CHW 
‘activation’ counseling session will increase 
the proportion of eligible people (>50 years) 
in with whom participants discuss RSV 
vaccination with, compared to text alone. 
Hypothesized mechanisms are that CHW 
counseling improves trust and knowledge of 
RSV vaccination and susceptibility, and the 
text-message nudges them to act on their 
intention to discuss RSV vaccine with family 
and people in their network.  
Rationale: Interventions targeted to the 
social network have the potential to reach a 
large number of people with one contact 
point (i.e. the effect of CHW counseling with 
one person can be amplified to reach 5 of 
their social network contacts) and can 
impact social norms at the inter-personal or 
community level. Prior studies assessing the impact of interventions on participant’s social 
network have been hampered by challenges documenting impact on social network contacts. 
Figure 5: Schema of Aim 3 ‘Activate Trial’ 

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To address this we will use ‘name generation techniques’54,55 used in our prior studies to elicit 
the eligible contacts (adults >50 years) of the 18-49 year old participants.  
4.4.2. 
Study Population 
CHWs and study staff will recruit from people accessing services or community fairs at LTF-
affiliated CBOs or attending cultural events in San Francisco. Study inclusion criteria include 
Latino adults 18-49. Detailed inclusion criteria are outlined in section 5.1.1.  
4.4.3. 
Study Design Aim 3 and Intervention Groups 
This is a two-arm type 1 effectiveness-implementation RCT randomized at the level of the 
individual (Figure 5) with the following study groups: 
Arm 1: Text message from a CBO: Participants will receive an educational flyer from a CHW 
about RSV vaccination and how people in their network can schedule vaccines and the ‘LTF 
hotline’ for help with navigation if needed. Then 4 weeks later receive a text-message nudge, 
with message content based on findings in Aim 1b. As in Aim 2, the text message will also 
provide a flyerwith vaccine information, eligibility, and scheduling from the LTF. 
Arm 2: CHW ‘activation’ counseling with text-message nudge: At enrollment participants 
will receive the same flyer as in Group 1. Then, within 2 weeks of enrollment participants will 
have a 20-minute scripted conversation (in person or phone) grounded in motivational 
interviewing principals of Five A’s. CHWs will assess participants beliefs and knowledge about 
RSV and vaccine effectiveness, safety, eligibility, and interest and barriers in recommending 
RSV vaccination to their friends or family. Then they will advise how to initiate conversations 
about RSV vaccination. CHWs will then assist, by assessing personal barriers to discussing 
vaccination with older adults. Then arrange next steps: CHWs will write down an action plan and 
give it to the participant. CHWs will also provide a hotline number for participants or their 
contacts to use for questions or support scheduling an appointment. Participants will receive a 
text-message nudge with scheduling and information 1 month after enrollment.   
4.4.4. 
Location of CHW interventions and survey procedures 
The CHW counseling and baseline survey will be done via Zoom or in person at either Mission 
Language Vocational School (Latino Task Force headquarters), ZSFG Clinical Research 
Center. Endpoint follow up can be done in-person or remotely over Zoom or the phone.  
4.4.5. 
Duration of study intervention  
The intervention will be received at baseline (CHW counseling) and the text will be received 4 
weeks after follow-up. The duration of study procedures is 90 days, but participants can be in 
the study up to 24 months from enrollment if they are selected for in depth interviews.   
4.5. 
Primary Completion  
The expected completion of the primary outcome of Aim 2 and 3 is 4 years after the study 
opens to accrual. 
4.6. 
Study Completion 
The expected study completion date is 5 years after the study opens to accrual. 

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5. Selection and Enrollment of Participants 
5.1. 
Eligibility Criteria 
5.1.1. 
Inclusion Criteria and Exclusion Criteria 
Inclusion and Exclusion criteria for all three aims are outlined in Table 4. 
Table 4: Inclusion and Exclusion Criteria  
Study  
Inclusion Criteria 
Exclusion Criteria 
Aim 1  
 
 
RSV Vaccine 
Confidence 
Survey  
(a) Adult age >18 years  
(b) Speaks Spanish or English 
 
Not able to provide 
informed consent  
 
 
Community 
Advisory Groups 
for Adaptation of 
Intervention 
1. Group 1:  
a. age >60 years  
b. speaks Spanish or English  
c. self-identifies as Latino/a/e/x and/or 
indigenous group from Latin America 
d. lives or works in San Francisco County or 
Daly City and able to come to in-person 
meetings in San Francisco 
2. Group 2:  
a. age 18-50  
b. speaks Spanish or English  
c. Self-identifies as Latino/a/e/x and/or 
indigenous group from Latin America 
d. lives or works in San Francisco or Daly City 
and able to come to in-person meetings in 
San Francisco 
 
Not able to provide 
informed consent 
 
Planning on moving 
out of San Francisco 
or Daly City area in 
12 months 
In Depth 
Interviews (Aim 1)  
(a) Self-identifies as Latino/a/e/x and/or indigenous 
group from Latin America 
(b) Speaks Spanish or English  
(c) Age >18 years  
 
 
Not able to provide 
informed consent 
 
Aim 2 ‘Motivate 
Trial’ 
Inclusion Criteria:  
(a) Age >50 years 
(b) Self-identify as Latino/a/x and/or indigenous 
groups from Latin America 
(a) Intent to move 
outside of San 
Francisco in the next 
year  

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(c) Eligible for RSV vaccination per current 
CDC/ACIP recommendations* 
(c) Fluent in Spanish or English 
(d) Has not received the RSV vaccine 
(e) Has a cell phone 
(f) Lives or works in San Francisco or Daly City 
(f) Able to provide informed consent  
 
* CDC/ACIP Eligibility for RSV Vaccination:  
(1) Age 75 years and older 
(2) Age 50-74 and one of the following medical 
comorbidities: cardiovascular disease (e.g 
coronary artery disease), lung disease (e.g 
COPD, asthma), advanced chronic kidney 
disease, diabetes, liver disorders, neurologic 
or neuromuscular conditions, hematologic 
disorders, moderate or severe immune 
compromise 
 
(b) Nursing home 
resident 
(c) Household 
member participating 
in Aim 1 or 2  
(d) Unable to provide 
consent 
 
Aim 3 ‘Activate 
Trial’ 
Inclusion Criteria:  
(a) Age 18-49 years 
(b) Self-identify as Latino/a/x and/or indigenous 
groups from Latin America 
(c) Fluent in English or Spanish  
(e) Has a cell phone  
(f) Has >1 family member or friend 50 years or older 
who they have seen or spoken to for >15 minutes in 
the last 6 months and who lives in the United States  
 
Exclusion Criteria:  
(a) Household 
member enrolled in 
Aim 1 or 2 
(b) Unable to provide 
consent 
 
5.2. 
Recruitment Methods for Aims 1-3  
5.2.1. 
Recruitment 
Bilingual study staff in partnership with community health workers will recruit eligible participants 
among people who are receiving services or attending community cultural or health fairs at 
Latino Task Force (LTF) community sites, CBOs affiliated with the Latino Task Force, or other 
events in the community. Study team will present the study to Latino Task Force community 

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meetings. Staff and community health workers will distribute IRB-approved flyers about the 
study at community-events and answer questions about the study. While CHWs will participate 
in outreach, enrollment will be done by UCSF study staff. Information about the study will be 
shared at Latino Task Force meetings and affiliated CBOs will receive recruitment flyers, that 
they can also post and share with client. If a client expresses interest in the study, the study 
staff will follow-up with the client to discuss the study further, screen for eligibility, and set a date 
for the baseline visit if the individual is interested in participating.  
5.2.2. 
Participant Incentives 
Participants will receive a gift card or cash incentive as compensation for their time. The amount 
of the incentive is suitable to compensate for time and transport, without being coercive and the 
amount has been reviewed with community partners. Incentive amount will be based on time 
and participants can receive up to the following amounts in gift card or cash:  
(1) Aim 1 vaccine confidence survey: up to $20 
(2) Aim 1 Community Advisory Board Meetings up to $60 per 60-90 minute sessions 
(3) Aims 1-3 90 min in-depth interviews over one study visit: up to $100 
(4) Baseline and Endpoint 30-minute Questionnaires for Aim 2 and Aim 3: up to $40 at Baseline 
visits and up to $40 for Endpoint visits 
(5) Participation in CHW Counseling Session 30 minutes: Up to $30 
 
5.3. 
Inclusion of Women and Minorities 
All participants in this study will self-identify as Latino and will be residents of work in San 
Francisco. The study is focused on Latinos, a health disparity population in the United States, 
because of the need to increase respiratory virus vaccine uptake in the Latino community. 
Latinos in the United States are disproportionately impacted by acute respiratory viral infections, 
and they historically have respiratory virus vaccine uptake compared to non-Latino White 
people. Women are expected to comprise approximately half of the participants this proposal. 
5.3.1. 
Recruitment of Women and Minorities 
To achieve representation of Latinos and women, we have partnered with the Latino Task Force 
and community groups that are trusted by the Latino community. in partnership with bilingual 
bicultural study staff, will recruit eligible participants among people who are receiving services or 
attending community cultural or health fairs at Latino Task Force (LTF) sites or Community 
Based Organizations (CBOs) affiliated with the Latino Task Force. The Latino Task Force hosts 
core activities at the Mission Language Vocational School. 
5.4. 
Inclusion Across the Lifespan 
This study will include adult participants aged 18-49 years old (Aim 1b & 3) and >50 years and 
older (Aims 1a & Aim 2). There is no upper age limit to this study. Children (age <18 years) are 
not included in this study as the study outcomes are not appropriate for children, as children are 
not eligible for RSV vaccination and not able to either discuss RSV vaccination with older adults 

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or not able to fully understand information being discussed during the Community Health 
Worker ‘activation’ counseling session.  
5.5. 
Participant Registration 
For Aims 2 & 3 (Activate and Motivate trials) a written, signed, informed consent form (ICF) and, 
for Aim 2 only, a Health Insurance Portability and Accountability Act (HIPAA) authorization must 
be obtained before any study-specific assessments are initiated.  A copy of the signed ICF will 
be given to the participant. The original will be kept on file with the study records.   
For Aim 1 community-based vaccination survey participants will review an informed consent 
information sheet prior to completing the anonymous survey.  
6. Study Intervention and Randomizations 
6.1. 
Randomization (Aim 2 & 3)  
Both Aims 2 and 3 are 2 arm trials and intervention groups are described in 4.3.3 (Aim 2) and 
4.4.3 (Aim 2).  After enrollment participants will then be randomized to one of two study groups. 
Randomization will be computer generated, block randomization with random block sizes of 2, 
stratified by sex. 
6.2. 
Interventionist Training, Tracking and Fidelity 
To ensure fidelity of the intervention we have outlined a detailed training program and fidelity 
checklist. In Figure 1 we outline our training timeline. In year 1, Dr. Marquez will adapt the 
training content from our COVID-19 ‘Motivate, Vaccinate, Activate’ intervention for RSV 
vaccination. The training materials will be reviewed by our community-academic core team and 
refined with CHWs during the production phase of Aim 1. In year 2, we will train CHWs to deliver 
the intervention and assess competency with written assessments and direct observation at the 
end of training. We will score competency with a fidelity checklist that includes fidelity to the 
intervention, accuracy of content, and participant satisfaction. Throughout the trial there will be 
direct observation to ensure fidelity to the CHW counseling sessions (first 5 participants and 
quarterly) and we will hold monthly CHW meetings to reinforce skills and address questions. 
This plan is guided by the NIH Behavior Change Consortium recommendations to ensure fidelity 
of treatment delivery56 through standardized training, ensuring provider skill acquisition, 
minimizing drift (with observation and feedback), and accommodating provider differences 
(tailoring intervention to CHWs). 
 
Details on measuring the fidelity counseling intervention in Aims 2 & 3. We will measure 
four dimensions of fidelity: (1) adherence (delivery as designed) through fidelity checklists—
direct observation and CHW fidelity-checklists (2) dosage (amount of intervention delivered) 
time and content measured through a CHW fidelity checklist, (3) quality, through participant 
post-intervention rating and an empathy question on the fidelity checklist (4) program 
differentiation, through fidelity checklist in the intervention and control (Table 2).57–59 The 
primary fidelity measure will be percent of activities completed on the fidelity checklist, 
measured by direct observation. In developing the fidelity checklists, we will follow the process 
outlined by Walton et al. 202059 and will assess adherence to each of the 5As. For example, for 
‘Assess’, observers will choose ‘Done’, ‘To Some Extent’, ‘Not Done’ after observing if the CHW 
assessed participants’ beliefs and knowledge about RSV susceptibility. Additionally, we will 

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assess quality of delivery using the validated empathy question from the Motivational Treatment 
Integrity Scale.60   
6.3. 
Participant Discontinuation/Withdrawal from the Study 
Participants are free to withdraw from participation in the study at any time upon request. 
An investigator may discontinue a participant from the study for the following reasons: 
• 
Unacceptable adverse event(s) 
• 
Significant study intervention non-compliance.  
• 
Lost-to-follow up; unable to contact participant (see Section 6.4 - Lost to Follow-Up) 
• 
Any event or medical condition or situation occurs such that continued collection of 
follow-up study data would not be in the best interest of the participant . 
• 
The participant meets an exclusion criterion (either newly developed or not previously 
recognized) that precludes further study participation 
6.4. 
Lost to Follow-up 
A participant will be considered lost to follow-up if he or she fails to return for scheduled visits 
and study staff are unable to contact the participant after at least 3 attempts. Before a 
participant is deemed lost to follow-up, the investigator or designee will make every effort to 
regain contact with the participant (where possible, 3 telephone calls and, if necessary, a letter 
to the participant’s last known mailing address or local equivalent methods). These contact 
attempts will be documented in the participant’s study file. Should the participant continue to be 
unreachable, he or she will be considered to have withdrawn from the study with a primary 
reason of lost to follow-up. 
7. Study Procedures and Assessments 
7.1. 
 Informed Consent and Enrollment 
Prior to consent, participants will be screened to determine eligibility in the intervention. A 
waiver of consent will be obtained to confirm eligibility during the screening process. Written 
informed consent to participate in the study will be obtained from all participants. Consent forms 
will be translated from the original English to Spanish. Participants who agree to take part and 
sign the consent form will be enrolled in the study. Participants who can neither read nor write 
will have an impartial witness present during the consenting process who will sign and date the 
consent form on a line provided for witnesses upon confirming that the participant’s consent is 
given voluntarily and freely. Illiterate participants may mark an X on the signature line if they 
cannot sign themselves and the witness will provide the date next to the participant’s signature 
line. 
Aim 1: Informed Consent procedures:  
• 
Community RSV Vaccine Confidence Survey: Informed consent information sheet. 
• 
Community Advisory Board Meetings: Electronic or written informed consent. 
• 
In depth interview:  Electronic or written informed consent. 

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Study Procedures AIM 1 (Developmental Aim) 
Prior to implementation of the randomized trial, we will adapt the intervention using the ADAPT-
ITT process (Figure 2).  Study procedures will include: a community member vaccine hesitancy 
survey (anonymous), observation of 3-5 community advisory groups process in adapting 
intervention, and qualitative interviews.  
Phase 1:  
a. Community RSV vaccine hesitancy survey: A 25-minute survey will include demographics 
(age, gender, income, country of birth), BeSD core questions, prior vaccine history, self-rated 
health, experiences with healthcare discrimination,21,23 social network influences about health 
decisions, acculturation scale.61  
 b. In-depth Interviews (IDI): 90-minute interviews will focus on (1) Drivers of RSV vaccine 
confidence to guide adaptation of CHW counseling (2) cultural tailoring and preferences for 
content of text message, CHW counseling and informational link in the text message, (3) Older 
adults’ preferences and attitudes about how best younger people can discuss RSV vaccination 
with them (>60 years) and (4) Barriers and facilitators to discussing vaccines with older adults in 
the IDI (18-50 years). Interviews will be conducted by bilingual and bicultural staff from UCSF, 
trained in qualitative methods. Based on our prior qualitative work on intervention design we 
anticipate adequate thematic saturation with N~40 in total for Aim 1.1 & 1.2. 
Community Advisory Board meetings (ADAPT-ITT):  Over 3-5 CAB meetings, the CAB will 
discuss RSV vaccine hesitancy, perceptions of intervention components (text and CHW 
counseling) and work with the study team to adapt the intervention components.  After the first 
iteration of the adapted intervention component they will ‘theatre test’ the intervention 
components with th study team and provide feedback to develop the final version of the 
intervention components for Aims 2 and 3. The size of community advisory groups is based on 
sizes used in ADAPT-ITT interventions43,62 and the language distribution mirrors the community 
that served by the LTF and UES. Groups are larger for 18–50-year-olds to incorporate the 
diversity of preferred languages and any differences in preferences among young adults (18-24 
years) vs. adults 25-50 years.  
7.2. 
Randomization and Interventions for Trials 
7.2.1. 
Randomization and Interventions for ‘Motivate’ Trial (Aim 2) 
This is a two-arm randomized type-1 effectiveness-implementation individually randomized trial. 
We will randomize individuals to one of the two study groups (see 8.2.2) with random block 
sizes of 2 and stratified by sex.  
The two randomization groups are described in 4.3.3 and are:   
Arm 1- Text message nudge  
Arm 2: CHW counseling and text message nudge 

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7.2.1.1. 
Procedures Aim 2 
Baseline survey: After providing 
informed consent, participants will 
complete a 30 minute baseline 
survey, which will include 
questions on demographics, 
knowledge of RSV and the RSV 
vaccine, vaccine confidence, 
acculturation scale.  We will use 
the standardized vaccine 
hesitancy scale and BeSD vaccine 
hesitancy scale.   
Intervention delivery: The 
schedule of interventions is 
outlined in Figure 6 and outlined in 
the Schedule of Activities in 
Section 7.3.  With texts sent 4 
weeks post-enrollment in both 
arms and the CHW counseling 
within 2 weeks of enrollment.  
Endpoint survey: Participants will receive a 60-day endpoint survey with similar questions to 
those asked at baseline: vaccine confidence, BeSD framework core-questions, self-reported 
vaccination status and location, location of vaccination, self-reported number of discussions of 
RSV vaccination with people >50 years, proportion who received text message. We will also 
assess implementation-specific factors: (1) Process measures (e.g. text messages received, 
access-related challenges in getting vaccinated, called LTF hotline), location of vaccination, 
access-related barriers to vaccination (i.e. challenges making an appointment) and (2) 
Pathways: (a) whether the interventions elicited responses along the intended pathways, e.g. 
did the text message positively reinforce or remind people to take action on intended behavior, 
did CHW counseling improve trust and perceptions of RSV susceptibility and (b) assess 
subjective rating or satisfaction of interventions by participants with Likert-style questions.  
Process Metrics/CHW log: CHW will enter the following process measures into a log that will be 
entered in REDcap: fidelity to counseling script, time for each motivation session, perceived 
client-specific barriers and facilitators, number of calls received or made for navigation and 
counseling.  
Text message receipt confirmation: Text-messages will be sent 4 weeks post-enrollment. 
Successful receipt will be assessed retrospectively via Twilio and self-report of reading the text 
will be assessed at the time of the endpoint questionnaire.  
Ascertainment of vaccination status: Vaccine status will be ascertained prior to text nudge and 
at 60 and 90 days through the medical record or California Immunization Registry (CAIR), the 
medical record, or proof of vaccination from a pharmacy. 
Semi-structured IDI with participants: In accordance with principles of Grounded Theory63, we 
will iteratively collect and rapidly analyze interview transcript data, continuing to select 
Figure 6: Schedule of Evaluations and Procedures 

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participants within theoretically informed categories (e.g. not only categories such as study 
group and vaccine uptake, but levels of acculturation or baseline level of engagement with 
primary care). The interview guide will be designed to elicit: i) perceptions, attitudes, 
preferences related to the study interventions received, ii. motivations and barriers to getting 
RSV vaccination (per BeSD framework, Figure 3), iii. implementation outcomes: satisfaction 
with intervention components. Based on prior qualitative work on behavioral interventions, we 
anticipate adequate thematic saturation with N-10-20 in each arm.  
Focus Groups with Key Stakeholders: We will conduct focus groups of CHWs and CBO leaders 
to assess barriers and facilitators of implementation, adoption, and maintenance of the 
intervention. We will conduct purposive sampling until we attain saturation of key themes, which 
we anticipate will be 2 focus groups of 6 CBO leaders within the LTF (N~12) in English and on 
Zoom and 2 in-person focus groups in Spanish with CHWs delivering the intervention (N~12).  
7.2.2. 
Randomization and Interventions for ‘Activate’ Trial (Aim 3) 
In a parallel structure to Aim 2 we will conduct a randomized trial of the intervention components 
(CHW counseling and text-message from a CBO) adapted from the Development phase (aim 
1). This is a two-arm type 1 effectiveness-implementation RCT randomized at the level of the 
individual with the following study groups outlined in section 4.4.3: 
Study Group 1: Text message nudge  
Study Group 2: CHW ‘activation’ counseling with text-message nudge 
7.2.2.1. 
Study Procedures Aim 3 
Enrollment and Randomization: Enrollment, randomization, and intervention delivery procedures 
are identical to Aim 2. We will use block randomization with block sizes of 2, with stratification 
by sex.  
Baseline Survey: The 25-minute questionnaire will include (1) RSV vaccine hesitancy 
questionnaire and demographics used in Aim 1 & 2, (2) questions on capability and confidence 
in recommending the vaccine, (3) Ego-centric (ego=participant) 
1st degree social networks of people >50 years (Figure 7). Using 
‘name generation’ techniques used widely in our prior studies, 
participants will be asked to list the age, gender, race/ethnicity, 
type of relationship, residence (district, city) and perceived RSV 
vaccine status of family and friends age of 50 and above. This 
number will be used as the denominator for the primary outcome 
and outcomes for each social network contact named will be 
assessed during the endpoint survey. 
 Endpoint Survey: Participants will complete a 60-day follow-up 
survey (in person preferred, but phone possible) to assess the 
proportion of people in their ‘named’ network at baseline with 
whom they discussed RSV vaccination. Participants will be shown 
the characteristics of each person (relationship, age) ‘named’ in 
their 1st degree older adult network and they will answer whether 
they discussed vaccination with that person, why or why not, and 
Figure 7: Sample questions 
for social network endpoint 

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the outcome of the conversation. See Figure 7 for an example of survey questions. 
Implementation barriers and facilitators will be assessed as in Aim 2, with a specific focus on 
whether the interventions elicited responses along the intended pathways and assess subjective 
rating or satisfaction of interventions by participants with Likert-style questions. The endpoint 
survey will also include questions about vaccine confidence and specifically assess changes in 
trust with the BeSD core question “How much do you trust the RSV vaccine?”.  
Process Metrics/CHW log: Same process measures and data collection method as described in 
Aim 2.  
Semi-structured IDI (participants) and key stakeholders: will be assessed: We will recruit a 
purposive sample from each study group who completed the study procedures to understand 
the mechanisms by which the interventions failed or succeeded and the characteristics of who 
did not respond to interventions. We will use the same procedures for IDIs as discussed in Aim 
2 and anticipate a sample size of N~15-25 per study group. 
Focus Groups with Key stakeholders: Methods are described in Aim 2 and we will use the same 
focus groups with key stakeholders to assess implementation barriers for both Aims 2 and Aim 
3 during the end of year 4 and quarter 1 of year 5. 

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7.3. 
Schedule of Activities (Aim 2 and 3) 
Aim 2 and 3 trials have a parallel structure, but differ by study population and content of interventions. However, the schedule of 
assessments and procedures is the same.  
Table 5: Participant Schedule of Activities  
Assessments/Procedures 
Screening 
 
 
Study 
Intervention 
Period 
 
End of Study 
Intervention 
Study Visit / Day  
(Window, # Days) 
Visit 0* 
 (-60 to 0 
days to D1) 
Visit 1 / D1 
(+/14) 
Day 14 
(Up to 14§ 
days after 
D1) 
Day 28 
 
Visit 2 / D 60 
(+ 14)^ 
Informed Consent1^ 
X 
 
 
 
 
 
Inclusion/Exclusion Criteria^ 
X 
 
 
 
 
 
Randomization^ 
 
X 
 
 
 
 
Baseline Questionnaire^ 
X 
 
 
 
 
 
CHW counseling session and 
navigation^ (Arm 2 only)  
 
 
X 
 
 
 
Text-message  
 
 
 
X 
 
 
Endpoint questionnaire^ 
 
 
 
 
X 
 
Outcome Ascertainment - via 
medical record or California 
Immunization Registry  
 
 
 
 
 
X 
In-depth interviews^† 
 
 
 
 
 
X 
 
1 Informed consent must be obtained prior to any study-specific procedures and may be obtained prior to the screening window. 
§Can take place up to 60 days after D1 if needed 
^Can done in-person or remotely (telephone or web-based platform such as Zoom) 
*Can be combined with Visit 1 
†For a subset of participants only 

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8. Reporting of Adverse Events  
This study includes 2 behavioral interventions (texting and CHW counseling) as well as 
completing surveys. This is a minimal risk to participants. Care will be taken to protect the 
privacy of participants in this study.  However, there is a risk that others may inadvertently see 
participants’ research or medical information, and thus privacy may be compromised. In the 
unlikely event that a serious adverse event (SAE) is considered possibly, probably or definitely 
related to the study, or in the event of major incidents or major protocol violations, reporting to 
University of California-San Francisco IRB will be reported as outlined in Table 6. Suspected 
events will be reviewed by study investigators prior to submission to the IRB. 
Table 6.  Event Reporting Timeline 
Institution 
Type of Events 
When to Report 
UCSF Human 
Research 
Protections 
Program (HRPP) 
 
Adverse events that UCSF PI determines are 1) 
serious, 2) related, and 3) unexpected or more 
frequent or severe than expected 
 
• 
Most events: Within 5 
working days of 
awareness 
• 
Related deaths and life-
threatening events: 
Immediately 
Major protocol violations 
 Within 10 working days of 
awareness 
Major incidents 
• 
Major incidents that are 
potential breaches of 
confidentiality: Within 48 
hours 
• 
Other major incidents: 
Within 10 working days of 
awareness 
9. Statistical Considerations 
This study includes a developmental aim (Aim 1) to adapt interventions tested in Aim 2 and 3. 
Herein we present the statistical design and power for randomized trials in Aim 2 and 3.  
In Aim 2, we will compare the effectiveness of two strategies— Arm 1: RSV vaccine information 
flyer at enrollment + text-message nudges vs. Arm 2: Community Health Worker (CHW) 
counseling and text message nudges—on RSV vaccine uptake among 400 Latino adults >50 
years. In Aim 3, we will compare the effectiveness of two strategies: Arm 1: RSV vaccine 
information flyer at enrollment + text-message nudges vs. Arm 2: Community Health Worker 
(CHW) ‘activation’ counseling and text message nudges —on enabling participants (18-49 years 
old) to discuss RSV vaccination with older adults in their family and social network. We will 
conduct in-depth qualitative interviews with a subset of participants from Aim 2 and 3, with 
stratified sampling based on key outcome measures. We will also describe implementation 
outcomes for text-messaging and CHW counseling, using metrics that align with the RE-AIM 
framework.64  

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9.1. 
Aim 1 Statistical Considerations 
Aim 1 is primarily a qualitative study and developmental aim, but it includes one quantitative 
survey.  We will use logistic regression to assess predictors of vaccine hesitancy with the 
primary outcome being unlikely to get or recommend the RSV Vaccine. Primary predictors 
include age, sex, acculturation level, preferred language.  
9.2. 
Aim 2 (Motivate Trial) Statistical Considerations  
Study Design: Two-arm randomized type-1 effectiveness-implementation individually 
randomized trial. 
Analysis Plan. We will compare the primary outcome of RSV vaccine uptake within 60 days 
between the two study arms using two broad statistical approaches: unadjusted analyses to 
explore average treatment effects and model adjusted estimates to reduce variance and 
examine effects for subpopulations. First, we will examine the intention-to-treat (ITT) effect, over 
all participants, for the primary outcome of vaccine uptake using the Fisher exact test. To 
account for participants which the CHW may not be able to reach, we will examine the average 
treatment effect on the treated (ATT).65 Second, we will use targeted maximum likelihood 
estimation (TMLE), a pre-specified approach to data-adaptively adjust for stratified 
randomization factors and additional baseline predictors of the outcome in order to improve 
precision.  RSV vaccine uptake will be ascertained through the California Immunization 
Registry, the medical record, or proof of vaccination from a pharmacy. Using an analogous 
approach, we will also compare intervention effectiveness on pre-specified secondary outcomes 
and within pre-specified subgroups: baseline high vaccine hesitancy, low trust of healthcare 
system, low acculturation (score<3.0), sex.66–68 These will be augmented by predictor analyses 
to elucidate risk factors for poor vaccine uptake, overall and by arm and exploratory machine 
learning analysis for treatment effect heterogeneity.69,70 Additionally, we will examine pathways 
of intervention action (i.e. direct and indirect effects) using formal mediation analyses, 
considering mediation by post-baseline trust and perceived benefits in the vaccine. Both 
predictor and mediation analyses will use TMLE.  
Implementation Outcomes: We will calculate implementation outcomes using the RE-AIM 
framework for each, through quantitative and qualitative analyses.   
Analysis of qualitative data: Interviews will be transcribed and analyze by the bilingual study 
team (Co-I, UCSF research staff, CHW) with a thematic analysis guided by initial analytic code 
list based on the Behavioral and Social Determinants (BeSD) of Vaccination Framework48,71, 
quantitative survey results, and outcomes for the RE-AIM framework. As not all responses may 
not map onto BeSD determinants and other pre-determined themes, an inductive approach will 
also be used to generate sub-themes within the initial coding scheme. At defined stages of the 
analysis, codes and definitions will be refined or expanded as needed. In weekly team 
meetings, members will discuss coding of rich or difficult segments to achieve consensus.  
9.2.1. 
Aim 2 Sample Size Considerations   
Based on our preliminary data and a national survey, we anticipate 28% RSV vaccine uptake in 
our text-only arm (20% with no intervention and 8% increase with text). Assuming complete data 
for the primary outcome of vaccine uptake reported by CAIR, the medical record, or proof of 
vaccination from a pharmacy and α=0.05, our sample size of N=200 per arm will conservatively 

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provide a minimum detectable ITT effect size of 10%. Assuming CHWs will be able to reach 
90% of participants assigned to the counseling arm, our sample will be able to provide a 
minimum detectable ATT of 10.9%; if participants assigned to counseling are particularly hard to 
reach and only 80% take part in CHW counseling, we will be able to provide a minimum 
detectable ATT effect 12.3%.   
Statistical power for secondary outcomes will depend on participation in the 60-day follow-up 
survey. If 10% of participants are lost to follow-up, the minimum detectable effects increase to 
10.6% for ITT, 11.5% for ATT if 90% of intervention arm participants receive counseling and 
12.9% for ATT if 80% of intervention arm participants receive counseling. Under a setting of 
high loss to follow-up, where 20% of participants in both arms are not reached for a follow-up 
survey, the minimum detectable effects increase to 11% for ITT, 12.2% for ATT if 90% of 
intervention arm participants receive counseling and 13.7% for ATT if 80% of intervention arm 
participants receive counseling. 
Estimated treatment effects for all outcomes will be improved with statistical modeling with 
TMLE. 
In a nested secondary pre-post analysis we will compare the proportion of people who received 
the RSV vaccine prior to the text-message to 30 days after the text.  
9.3. 
Aim 3 (Activate Trial) Analysis Plan  
Aim 3 Study Design: Two-arm randomized type-1 effectiveness-implementation individually 
randomized trial. 
Aim 3 Analysis Plan: We will take an analogous analytic approach to Aim 2 to evaluate our 
primary outcome, ‘the average proportion of older adult contacts with whom RSV vaccination 
was discussed’ between the two study arms’ and secondary outcomes, together with pre-
specified subgroup analyses (age group 18-29 vs. 30-49 years). We will also undertake 
additional social network analyses to assess the relationship between egocentric network 
characteristics and the odds of discussing RSV vaccination: network size, type of relationship 
(e.g grandmother vs. aunt), characteristics of the participant (e.g. lives in multigenerational 
household, vaccine confident, age, acculturation), by study arm and pooled across arms. 
Implementation Outcomes: We will use definitions outlined in Table 2 and analogous 
quantitative and qualitative methods outlined in Aim 2.   
In a nested secondary pre-post analysis we will compare the proportion of people who 
discussed the RSV vaccine with eligible family or friends prior to the text-message to 30 days 
after the text.  
9.3.1. 
Aim 3 Sample size considerations 
As with the secondary outcomes for Aim 2, statistical power will depend of participation in the 
60-day follow-up interview. Assuming 10% attrition for the 175 participants in each arm, we will 
be able to detect a minimum ITT effect of 11% for any binary outcomes. For our primary 
outcome, assuming a standard deviation (Standard Deviation) of 0.3 for the proportion of adults 
contacted, with 175 participants/arm we will have 80% power (using α-0.05) to detect at least a 
10% absolute increase (e.g. from 30% to 40%) in the average proportion of older adult contacts 
with whom RSV vaccination was discussed.   

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9.3.2. 
Randomization and Blinding 
Randomization for Aim 2 and 3 are referenced in section 6.1.  The study statistician will be 
blinded to treatment arm.  
9.3.3. 
Stratification Factors 
We will also compare intervention effectiveness on pre-specified secondary outcomes and 
within pre-specified subgroups: baseline high vaccine hesitancy, low trust of healthcare system, 
low acculturation (score<3.0)61, sex. These will be augmented by predictor analyses to elucidate 
risk factors for poor vaccine uptake, overall and by arm,67,72 and exploratory machine learning 
analysis for treatment effect heterogeneity69,70. Block randomization by sex: Rationale is to 
facilitate even allocation of intervention for men and women. 
10. Study Management 
10.1. Pre-study Documentation 
Before initiating this trial, the PI will have written and dated approval from the Institutional 
Review Board for the protocol, written informed consent form, subject recruitment materials, and 
any other written information to be provided to participants before any protocol related 
procedures are performed on any participants.   
The PI must comply with GCP/ICH guidelines and all applicable regulatory requirements.   
10.2. Institutional Review Board Approval 
The protocol, the proposed informed consent form, and all forms of participant-facing materials 
related to the study (e.g., advertisements used to recruit participants) will be reviewed and 
approved by the IRB.  The initial protocol and all protocol amendments must be approved by the 
IRB prior to implementation.   
10.3. Changes in the Protocol 
Once the protocol has been approved by the IRB, any changes to the protocol must be 
documented in the form of an amendment.  The amendment must be signed by the PI and 
approved by the IRB prior to implementation.   
If it becomes necessary to alter the protocol to eliminate an immediate hazard to participants, an 
amendment may be implemented prior to IRB approval.  In this circumstance, however, the PI 
must then notify the IRB according to institutional requirements.   
10.4. Publications 
The preparation and submittal for publication of manuscripts containing the study results shall 
be in accordance with a process determined by mutual written agreement among the Sponsor-
Investigator and collaborators.  
 

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