Behavior Change in Context to Contain the Spread of COVID-19

Project BECCCS (=Behavior Change in Context to Contain the Spread of COVID-19) aims to optimise and test a behaviour change intervention to promote correct hand hygiene at key times in the short and long term.

The study's specific aims are:

1. Optimisation phase: Identify the most effective combination and sequence of three different intervention modules (habit, motivation, social norms), and to assess usability and fidelity measures in order to optimise the intervention
2. Evaluation phase: Test the final intervention against an active control group (basic app content including "Federal Office of Public Health" advice)

Study design:

In this study, the MOST methodology (multiphase optimization strategy; Collins et al., 2014) will be applied. First, the most effective intervention components for specific target groups will be determined, which is called the optimisation phase. To this end, the investigators run a parallel randomized trial that investigates all combinations of three interventions modules (= 9 combinations) in terms of its usability and its effectiveness.

To collect in-depth information about usability and feasibility, the investigators will additionally run a qualitative survey with a small subsample of the trial.

After this optimisation phase, the intervention's effectiveness will be tested against an active control group in a randomized controlled trial, which is called the evaluation phase.

For the optimisation phase, participants will be randomly assigned to one of nine conditions. All participants are randomized into one of nine intervention group in a 1:1:1:1:1:1:1:1 ratio. For the randomization, an even randomization procedure is applied using Qualtrics. Because the randomization is even, the probability is fixed if the number of the participants can be divided by 9, it means that at the end the investigators will have exactly even number of participants in each group.

In the evaluation phase, the optimised intervention from the optimisation phase will be tested in an RCT. To this end, participants will be randomly assigned to one of two conditions: final intervention vs. active control group. The active control group has access to the app, receives the basic module to test the effect of the final intervention, will answer the three questionnaires (pre-test, post-test, follow-up), and the short questionnaires (diary days).

Recruitment and informed consent procedure:

The sample will be recruited via Facebook and Instagram. Those who click on the link of the campaign will lead to a landing page with the relevant study information. Here, participants read the study info and enter their e-mail address. When they click on "send", an info box explains that an email has been sent including the link to the actual study.

In the mail, the participants can access via link to an eligibility and consent survey with detailed information about the nature of the study (=optimization and evaluation phase), its purpose, the procedures involved, the expected duration, the potential risks and benefits, any discomfort it may entail and finally an e-consent form to give consent to the study electronically. If people meet all inclusion criteria, the participants can directly sign with the mouse (on computer) or finger (on mobile device) the consent form.

After the participants agree to participate in the study, they receive a registration code via e-Mail to participate in the study as well as a signed copy of the consent form (at the latest of one week after giving consent electronically).

In the mail, the participants are guided to download the app "soapp" from their app store with the registration code. After downloading the app, they have to register and tip in the registration code. After that, they start with the first questionnaire T1 (optimization phase) or pre-test (evaluation phase).

Study procedure:

The duration of the study is 5 weeks (optimisation phase) plus a 6-month follow-up in the evaluation phase. Each participant receives two different intervention modules which each last 2 weeks.

After downloading the study app, the participants receive the first baseline questionnaire (T1 or pre-test).

Optimization phase: The day after T1, people attend a diary day. The diary day includes five 1-minute-questionnaires during one day. People will be informed that the intervention starts on the subsequent day after the diary day. The intervention will take four weeks and includes two modules. During the first module, people will attend another diary day at the end of each week (2 in total during one module). On the subsequent day of the last dairy day of the first module, people will receive the second questionnaire (T2). After T2, the second intervention module follows in the same structure: The participants follow the instructions of the intervention and their hand hygiene behaviour is surveyed on the last day of each week using the short questionnaire within the diary day. A day after the participants completed the last diary day and with that the second module, they receive the last questionnaire (T3). Additionally, to the normal questionnaire, the participants can indicate at T3, whether they are willing to take part in a qualitative survey. Here, people will be interviewed via telephone by a study member. This interview will take around 30 minutes for the participants, where they will be asked questions about the usability of the app and their experience with the intervention modules. This information will be used to improve the study app before starting with the evaluation phase. By the end of the study, the participants will have completed three questionnaires (T1-T3) and five short-questionnaires.

Evaluation phase: The day after the pre-test questionnaire, people attend a diary day to assess their previous hand hygiene behaviour. People will be informed that the intervention starts on the subsequent day after the diary day. The intervention will run for four weeks. During these four weeks, people will attend another diary day at the end of each week (4 in total during the total intervention). A day after the last diary day of the intervention, participants are asked to fill in the second questionnaire (post-test). In the evaluation phase, the participants will receive a six-month follow-up. They will first attend a diary day after 6 months after the intervention started and will then receive the follow-up questionnaire the subsequent day. By the end of the study, the participants will have completed three questionnaires (pre-test, post-test, follow-up) and six short-questionnaires.

Hypotheses:

Optimisation:

Hyp.1: The intervention groups show a significant increase in correct hand hygiene behaviour at key times (T3).

Hyp.2: The intervention groups significantly differ in their effects on correct hand hygiene behaviour at key times (T1-T3).

Hyp.3. The intervention groups show a significant increase in (not correct) hand hygiene behaviour at key times (T3).

Hyp.4. The groups attending a motivation module show a significant increase in a) intention, b) self-efficacy, c) outcome expectancies and d) attitude from T1 to the post measures.

Hyp.5. The groups attending a habit module show a significant increase in a) habit strength, b) action control, and c) planning from T1 to the post measures.

Hyp.6. The groups attending a social norms module show a significant increase in a) injunctive norms and b) descriptive norms from T1 to the post measures.

Evaluation:

Hyp. 7. The intervention group show a greater increase in correct hand hygiene behaviour at key times at the post measure (H7a) and at 6-month follow-up (H7b) compared to the control group.

Hyp. 8 The intervention group show a significant increase in the targeted behavioural determinants that are included compared to the control group at the post-intervention measure (H8a) and at 6-month follow-up (H8b). \[the exact behavioural determinants depend on the results of the optimisation phase\].

Statistics:

In the optimisation phase, 387 subjects are to be randomized. This sample size was determined with an a priori power analysis with g\*power (Faul et al., 2009). The aim is that a statistical analysis using repeated-measures ANOVA with a within-between-interaction with a power of 0.80 and α = 0.05, a small effect of f =0.1 should be detectable. Accounting for 20% attrition, this leads to N = 465 for the enrolment in the parallel control trial.

In the evaluation phase, 204 new subjects are to be randomized. The aim is that that a statistical analysis using an independent samples t-test adopting an error probability and statistical power of α = 0.05 and β = 0.80, at least a small intermediate intervention effect of Cohen's d = 0.35 should be detectable (Faul et al., 2007). Accounting for 20% attrition, this leads to N = 245 for the enrolment in the RCT.

There is no statistical criterion of termination of trial. If more participate are included in the study than 387 people in the optimisation phase and 204 people in the evaluation phase, the results can be examined in more detail and more complex contexts in terms of differential indication can be examined thereby helping to improve the intervention.

Planned Analyses:

The analysed sample includes all randomized participants. The analyses are carried out on the basis of the intention-to-treat approach.

In the optimisation phase, the primary analyses will be conducted (T1-T3) to test the hypotheses using R and SPSS after 387 participants have completed the study.

To address the primary research question, the main effect of a univariate analysis of variance with repeated measures will be analysed. After, post-hoc comparison analyses with independent t-test will be conducted between all groups. Last, multiple linear regression analyses will be conducted to test the effect of the targeted behavioural determinants on the outcome.

In the evaluation phase, the primary analyses will be conducted (pre-test, post-test, follow-up) to test the hypotheses using R and SPSS after 204 participants have completed the study. Secondary follow-up analyses will be conducted six months later. Multiple linear regression analyses will be conducted to test the effect of the targeted behavioural determinants on the outcome and to test mediation hypotheses.

The qualitative data in the optimisation phase are analysed by using thematic analysis (Braun \& Clarke, 2006).

No interim analyses or safety analyses are planned. Deviations from the planned analyses will be reported in the final report.

Handling of missing data and drop-outs:

The main analysis will be performed according to the intention-to-treat (ITT) principle. The ITT analysis includes every subject who is randomized according to randomized study group. It ignores noncompliance, protocol deviations as not adhering to the intervention modules, and anything that happens after randomization. Participants who withdrew consent are excluded from ITT analysis. ITT analysis avoids overoptimistic estimates of the efficacy of an intervention resulting from the removal of non-compliers by accepting that noncompliance and protocol deviations are likely to occur in practice.

To analyse the investigators' hypotheses and research questions, the investigators follow-the ITT analysis strategy. This includes: 1) Attempt to follow up all randomized individuals, even if they withdraw from allocated group. 2) Perform a main analysis that is valid under a plausible assumption about the missing data and that uses all observed data 3) Perform sensitivity analyses to explore the impact of departures from the assumption made in the main analysis 4) Account for all randomized individuals, at least in the sensitivity analyses.

Eligibility Criteria:
Inclusion Criteria:

* Be at least 18 years old
* Have signed an electronically written informed consent (online) form to participate in the study
* Own a smartphone with mobile access to the internet
* Be proficient in the German language to the degree that they understand the contents and instructions of the study.