Covid-19: Covaxin booster has 77.8 per cent efficacy against variants

Amid the debate over the efficacy of a booster dose against new variants of SARSCoV2 the virus that causes COVID19 a recent study published in the journal Nature Scientific Report stated that Covaxin is equally effective as 20 other global vaccines Health experts however remained cautious and called for longer studies on preventing occurrence of autoimmune diseases in people with rheumatoid markers affecting heart kidney brain blood and liver as a result of frequent booster dosesAlso readMumbai sees 238 new Covid19 cases two deathsVaccine efficacyldquoCovaxin is an ancestral wholevirion inactivated SARSCoV2 vaccine that is adsorbed onto alum adjuvant to improve its immunogenicity In 2020 the 6microg dose of Covaxin was selected for assessment in a phase3 efficacy trial in which it had demonstrated an overall efficacy of 778 per cent against any COVID19 and 652 per cent against the Delta variant A recently published Phase2 doubleblind study in a peerreviewed medical journal that assessed the persistence of neutralising antibodies up to 6 months after a two or three doses of Covaxin in a randomised controlled trial The study has reported persistence of humoral and cell mediated immunity up to 12 months Administration of a third dose increased neutralisation titers against both ancestral and variant strains namely Alpha Beta Delta Delta Plus and Omicron with persistent Tcell immunity Thus seroconversion rate remained high in boosted recipients compared to non boosted individuals even after 6 monthsrdquo said Dr Subhash Hira professor of Global Health at University of WashingtonSeattle and a member of several COVIDvaccine panels at WHOGenevaHe added ldquoHowever some studies have raised concerns about excessive use of booster vaccines since they also cause production of autoantibodies that lead to cardiomyopathies brain clouding and kidneyliver damages in people who are predisposed to autoimmune diseases with rheumatoid markersrdquoldquoAfter analysing this report it is clear that vaccines definitely help to protect against COVID19 infection So we must encourage all people to take vaccines Booster dose is also important to get protection against new variants of concernrdquo said Dr Santosh Bansode head of the department Emergency Medicine Wockhardt hospitalsDr Wiqar Shaikh professor of Medicine Grant Medical College and Sir JJ Group of Hospitals said that he has noted the recent study on persistence of immunity and impact of third dose of Covaxin and added that the accepted norm worldwide is that boosters have to be given to protect the population ldquoHowever there is no clarity on the no of booster doses required Besides there has been a repeated demand everywhere that separate vaccines will need to be given for COVID19 variantsrdquo he saidMakerSpeakIn a media statement Ms Bharat Biotech stated that the study was conducted on 184 subjects who were evaluated for safety neutralising antibody responses against variants of concern binding antibodies against spike protein RBD N proteins and for memory T and B cell responses to demonstrate cell mediated immunity Dr Krishna Ella chairman and MD Bharat Biotech said ldquoOur team has now demonstrated that Covaxin is a multiepitope vaccine with antibodies against spike RBD and N proteins Post booster dose it has proven neutralising antibody responses against variants of concern and longterm 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 variantsrdquo