E-Paper
Covaxin booster safe, ensures persistent immunity: ICMR study
Covaxin booster dose is safe and necessary as it ensures persistent immunity that minimises breakthrough Covid infection, according to a new study by ICMR
Pune: The Covaxin booster dose is safe and necessary as it ensures persistent immunity that minimises breakthrough Covid infection, according to a new study by Indian Council of Medical Research (ICMR).
The study also showed an 18.5-fold increase in neutralisation antibody titers against the Omicron variant after a Covaxin booster dose, as compared with the non-booster dose recipient.
The study ‘Persistence of Immunity and Impact of Third Dose of Inactivated Covid-19 vaccine Against Emerging Variants’ published on July 14 in Nature -Scientific Reports journal.
The administration of a third dose of Covaxin increased neutralisation titers against both homologous (D614G) and heterologous strains (Alpha, Beta, Delta, Delta Plus and Omicron) with a slight increase in B cell memory responses, stated the study.
Study researchers have said in the report that the emergence of SARS-CoV-2 variants of concern has raised questions about the durability of the neutralising antibody responses. Diminished vaccine effectiveness against variants of concern such as Alpha, Beta, Delta and Omicron have been reported for several authorised vaccines with two doses of vaccination.Understanding the persistence of neutralising antibody responses against variants of concern has become vital to assess the need for additional booster doses, Krishna Mohan Vadrevu, director with Bharat Biotech International Limited (BBIL), said in the report.
BBIL, along with scientists from Indian Council of Medical Research-National Institute of Virology, Pune, Nizam’s Institute of Medical Sciences, Hyderabad, All India Institute of Medical Sciences, Patna, and others assessed the persistence of immunogenicity up to six months after two or three doses of Covaxin and the safety of a booster dose in an ongoing phase 2, double-blind, randomised controlled trial .
There was a decline of antibody levels after the second dose of Covaxin. However, more than 75 per cent participants followed up six months after the dose still had detectable neutralising antibody responses to the homologous SARS-CoV2 strain D614G, Dr Pragya Yadav, senior scientist from ICMR-NIV, noted the report.
For the booster dose trial, around 184 from the parent study were re-enrolled to receive the precautionary dose or placebo. The seroconversion rate remains high in boosted recipients compared to non-booster, even after six months, post third dose against variants. No serious adverse events were observed, except pain at the injection site, itching and redness, study researchers have said.
Dr. Krishna Ella, chairman and managing director, Bharat Biotech, said, “Our team has now demonstrated that Covaxin is a multi-epitope vaccine with antibodies against spike, RBD and N proteins. Post booster dose, it has proven neutralising antibody responses against variants of concern and long-term protection through memory T and B cell responses. We have now achieved our goal of developing a safe and efficacious vaccine with long term protection against a spectrum of variants.”
“Covaxin is formulated uniquely such that the same dosage can be administered to adults and children alike, for primary and booster doses, making it truly a universal vaccine. Bharat Biotech has a stockpile of more than 50 million doses ready to be distributed as required,” added Ella.
