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Randomized Trial of COVID-19 Booster Vaccinations (Cobovax Study)

NCT05057169 · Status: COMPLETED · Phase: PHASE4 · Type: INTERVENTIONAL · Enrollment: 451

Last updated 2026-05-15

No results posted yet for this study

Summary

Randomized comparison of 3rd dose with inactivated vaccine (CoronaVac) or mRNA vaccine (Comirnaty) in adults who previously received two doses of CoronaVac (Sinovac) or two doses of BNT162b2 (Comirnaty, BioNTech/Fosun Pharma) at least 6 months earlier.

Conditions

  • COVID-19 Vaccination

Interventions

BIOLOGICAL

BNT162b2

BNT162b2 is a nucleoside-modified mRNA encoding the trimerized SARS-CoV-2 spike glycoprotein. The vaccine is formulated in lipid nanoparticles that increase the efficiency of delivery of the mRNA into cells after intramuscular injection. BNT162b2 encodes the SARS- CoV-2 full-length spike, modified by two proline mutations to lock it in the prefusion conformation and more closely recreate the intact virus with which the elicited virus- neutralizing antibodies interact. mRNA vaccines use the pathogen's genetic code as the vaccine; hence they exploit the host cells to translate the code and generate the target spike protein. The protein then acts as an intracellular antigen to stimulate the immune response of the vaccinated individual. The mRNA is then degraded within days.

BIOLOGICAL

CoronaVac

CoronaVac is a Vero cell-based, aluminium hydroxide-adjuvanted, β-propiolactone- inactivated vaccine based on the CZ02 strain. This strain of SARS-CoV-2 was isolated from the bronchoalveolar lavage of a hospitalized patient and is closely related to the 2019-nCoV- BetaCoV Wuhan/WIV04/2019 strain. Each 0.5 ml dose is composed of 3 μg of inactivated SARS-CoV-2 virus. The excipients are aluminium hydroxide, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium chloride, and water for injection.

Sponsors & Collaborators

  • The University of Hong Kong

    lead OTHER

Principal Investigators

  • Benjamin J Cowling, PhD · The University of Hong Kong

Study Design

Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
TRIPLE
Model
PARALLEL

Eligibility

Min Age
18 Years
Sex
ALL
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2021-11-18
Primary Completion
2024-12-31
Completion
2025-12-31

Countries

  • Hong Kong

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT05057169 on ClinicalTrials.gov