Reactogenicity, Safety, and Immunogenicity of Covid-19 Vaccine Booster

Study Overview
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Brief Summary
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Preliminary data suggest that inactivated vaccine-induced neutralizing antibodies against SARS-CoV-2 decrease at six months after vaccination. Observational, unpublished data also indicate that vaccine effectiveness against Covid-19 wanes over time. Thus, the investigators aimed to determine the reactogenicity, safety, and immunogenicity of a homologous or heterologous booster of SARS-CoV-2 vaccines among people already immunized with an inactivated SARS-CoV-2 vaccine. The study focuses on the elderly population and healthcare workers.

Official Title
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Reactogenicidad, Seguridad e Inmunogenicidad de Dosis de Refuerzo de Vacunas Contra SARS-CoV-2 en Chile (Estudio REFUERZO)

Conditions
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Covid19

Intervention / Treatment
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* Biological: Placebo
* Biological: Inactivated vaccine booster
* Biological: mRNA vaccine booster
* Drug: Viral vector vaccine booster


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Full immunization with CoronaVac (2 doses; 0,28) prior to April 15, 2021 Being a resident of any of the eligible Nursing Homes (located in the Metropolitan Region of Chile) Healthcare workers of one of the eligible Nursing Homes. Healthcare workers of Hospital de Urgencia Asistencia Publica (HUAP, Santiago, Chile) Exclusion Criteria: Prior history of Covid-19 Not able to consent

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Inactivated vaccine booster<br>One standard IM CoronaVac dose (0.5 mL) | Biological: Inactivated vaccine booster<br>* 0.5 mL IM<br>* Other names: CoronaVac;|
| Experimental: mRNA vaccine booster<br>One standard IM BNT162b2 dose (0.3 mL) | Biological: mRNA vaccine booster<br>* 0.3 mL IM<br>* Other names: BNT162b2;|
| Experimental: Viral vector vaccine booster<br>One standard IM ChAdOx1 dose (0.5 mL) | Drug: Viral vector vaccine booster<br>* 0.5 mL IM<br>* Other names: ChAdOx1;|
| Placebo Comparator: Placebo<br>Saline solution IM (0.3 mL) | Biological: Placebo<br>* 0.3 mL IM saline solution<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Early humoral response | Change in SARS-CoV-2 neutralizing antibody levels | Baseline (90-120 days after second dose of CoronaVac) and 15 days post booster dose | 
| Immunogenicity | Change in SARS-CoV-2 neutralizing antibody levels | Baseline, 15, 30, 60, and 90 days post booster dose | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Reactogenicity | Solicited and unsolicited. Events will be assessed by scheduled visits performed by nursing home´s nurse stuff. Telephone numbers, including the PI´s cell phone will be available 24/7 for reporting any unsolicited reaction. Reporting will follow national regulations available at the Institute of Public Health web page (https://www.ispch.cl/anamed/farmacovigilancia/vacunas/como-notificar-esavi/) | days 7, 28, and 3 months post booster dose | 
| Safety of booster dose | Number of subjects presenting serious adverse events post booster dose. | In addition to the scheduled visits mentioned in Outcome 3, Telephone numbers, including the PI´s cell phone will be available 24/7 throughout the study (1 year) for reporting any unsolicited reaction. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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covid-19, inactivated vaccine, booster, Chile