COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Primary Prevention Vadrevu KM, Ganneru B, Reddy S, et al. Persistence of immunity and impact of third dose of inactivated COVID-19 vaccine against emerging variants. Sci Rep. 2022 Jul 14;12(1):12038. doi: 10.1038/s41598-022-16097-3.
PICO Terms
adolescent (P) adult (P) adverse reactions; safety (O) anti-nucleocapsid protein IgG (O) anti-RBD IgG; anti-receptor-binding domain IgG (O) booster; third dose (I/C) Covaxin vaccine; BBV152; Bharat Biotech; inactivated virus (I/C) delta; B.1.617.2; variant of concern; VOC (P) fully vaccinated (I/C) geometric mean titres (O) healthy (P) immunogenicity (O) neutralizing antibodies (O) reactogenicity (O) SARS-CoV-2 spike protein-binding antibodies (O) seroconversion (O) spike-specific T cell response (O) T-cell response (O) vaccine efficacy (O) waning over time (O)
Demographic Information
Geriatric Population
60 years to <70 years
Female Male
Asian Indian South Asian

This is a comprehensive report on immunogenicity of COVAXIN® booster dose against ancestral and Variants of Concern (VOCs) up to 12 months. It is well known that neutralizing antibodies induced by COVID-19 vaccines wane within 6 months of vaccination leading to questions on the effectiveness of two-dose vaccination against breakthrough infections. Therefore, we assessed the persistence of immunogenicity up to 6 months after a two or three-dose with BBV152 and the safety of a booster dose in an ongoing phase 2, double-blind, randomized controlled trial ( NCT04471519). We report persistence of humoral and cell mediated immunity up to 12 months of vaccination, despite decline in the magnitude of antibody titers. Administration of a third dose of BBV152 increased neutralization titers against both homologous (D614G) and heterologous strains (Alpha, Beta, Delta, Delta Plus and Omicron) with a slight increase in B cell memory responses. Thus, seronversion rate remain high in boosted recipients compared to non-booster, even after 6 months, post third dose against variants. No serious adverse events observed, except pain at the injection site, itching and redness. Hence, these results indicate that a booster dose of BBV152 is safe and necessary to ensure persistent immunity to minimize breakthrough infections of COVID-19, due to newly emerging variants.Trial registration: Registered with the Clinical Trials Registry (India) No. CTRI/2021/04/032942, dated 19/04/2021 and on NCT04471519.

Discipline / Specialty Area Score
Public Health
Pediatrics (General)
Comments from MORE raters

Public Health rater

This article based on India's vaccines, suggests that the current vaccines against variants of concern have immune responses after six months of immunizations as boosters.