Reactogenicity, Safety, and Immunogenicity of Covid-19 Vaccine Booster (REFUERZO)

Universidad del Desarrollo

Status and phase: Unknown; Phase 2

Conditions: Covid19

Treatments: Biological: Placebo; Biological: Inactivated vaccine booster; Biological: mRNA vaccine booster; Drug: Viral vector vaccine booster

Study type: Interventional

Funder types: Other

Identifiers

NCT04992182

2021-71

Details and patient eligibility

About

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 Observational, unpublished data also indicate that vaccine effectiveness against Covid-19 wanes over time.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.

Enrollment: 534 patients

Sex: All

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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534 participants in 4 patient groups, including a placebo group

Inactivated vaccine booster

Experimental group

Description:

One standard IM CoronaVac dose (0.5 mL)

Treatment:

Biological: Inactivated vaccine booster

mRNA vaccine booster

Experimental group

Description:

One standard IM BNT162b2 dose (0.3 mL)

Treatment:

Biological: mRNA vaccine booster

Viral vector vaccine booster

Experimental group

Description:

One standard IM ChAdOx1 dose (0.5 mL)

Treatment:

Drug: Viral vector vaccine booster

Placebo

Placebo Comparator group

Description:

Saline solution IM (0.3 mL)

Treatment:

Biological: Placebo