A study by Bharat Biotech and the Indian Council of Medical Research-National Institute of Virology, Pune, found that a third booster dose of Covaxin, administered six months after the second dose, induced both memory B and T cells and led to a pronounced increase in T-cell responses, indicating that the inactivated virus vaccine may be able to confer long-term protective efficacy against severe SARS-CoV-2.
Findings from a study on medRxiv that carries pre-prints of research publications before they are peer-reviewed indicate that a booster shot for Covaxin is safe and may be necessary to provide lasting immunity to prevent breakout infections, according to the findings.
Neutralization titers against SARS-CoV-2 wild-type and Delta variants were found to be five times higher after a two-dose schedule of Covaxin and similar increases in neutralizing antibodies against Alpha, Beta, Delta plus variants were observed, according to the researchers of the study titled “Persistence of immunity and impact of a third (booster) dose of an inactivated SARS-CoV-2 vaccine, BBV152; a phase 2, double-blind, randomized controlled
Researchers found that cell-mediated immunity and neutralizing antibodies to homologous (D614G) and heterologous (Alpha, Beta, Delta, and Delta plus) strains remained above baseline six months following a two-dose vaccination with Covaxin. However, the degree of responses decreased.
Anti-SARS-CoV-2 antibody levels rose 19 to 97% following the third injection, indicating that a booster dosage may be necessary in order to prevent new infections from occurring, according to the study.
Dr Krishna Ella, CMD of Bharat Biotech, described the results as “promising.” “A firm foundation has been laid for our goal of providing Covaxin as a booster dose following these results. Covaxin, a two-dose primary and booster vaccine for adults and children, has met our goal of producing an universal vaccine against Covid-19. Covaxin can now be used as a global vaccine because of this.”
The vaccination produces memory B and T cells with unique CD4 and CD8 phenotypes, according to the company. Vaccine and placebo reactions were also found to be similar, with no major side effects noted.
“As long as the severe disease is kept at bay, the effectiveness of the vaccine against symptomatic disease is predicted to drop with time and new varieties to arise. As more evidence becomes available, Bharat Biotech feels that a third dose may be necessary to retain the best possible level of protection “according to what they claimed, the company.