Vaccine maker Bharat Biotech on Saturday announced the results of its trial studying the immunogenicity and safety of its COVID-19 vaccine Covaxin as a booster dose. It said the booster dose of Covaxin is safe and highly immunogenic against all the variants of the coronavirus.
In a statement, the company said Covaxin is the first vaccine in India to report safety and immunogenicity results from a booster dose clinical trial. The vaccine manufacturer said that the neutralisation antibody titers were five times higher after the booster dose as compared to after two doses.
In the trial, the participants received a third booster dose of Covaxin six months after taking the second dose.
"The analysis showed, six months after a two-dose BBV152 vaccination series cell-mediated immunity and neutralising antibodies to both homologous (D614G) and heterologous strains (Alpha, Beta, Delta, and Delta plus) persisted above baseline, although the magnitude of the responses had declined," the company said.
It said that the neutralising antibodies against homologous and heterologous SARS-CoV-2 variants increased 19 to 265 fold after a third vaccination.
"The booster dose led to pronounced increase in CD4 and CD8 responses. This may allow Covaxin to confer long term protective efficacy against severe SARS-CoV-2," the statement said.
"The phase 2, double-blind, randomised controlled Covaxin trial demonstrated long-term safety with no serious adverse events," Bharat Biotech said.
While protection against severe disease remains high across the full six months, a decline in efficacy against symptomatic disease over time and the continued emergence of variants are expected, the Hyderabad-based company said. "Based on emerging data, Bharat Biotech believes that a third dose may be beneficial to maintain the highest levels of protection."
India will begin administering the third dose or 'precaution dose' to healthcare and frontline workers and those above 60 years of age with comorbidities from January 10.
The government has said that there will be no mix-and-match for the precaution doses. This means those who took Covishield will take Covishield again and those who were given the Covaxin jab, will get a third dose of Covaxin.
Earlier on January 3, India also began vaccinating adolescents in the 15-18 age group against COVID-19. Covaxin is the only vaccine available to this age group as per the guidelines issued by the Union Health Ministry. However, on Friday, Bharat Biotech expressed concern over unauthorised COVID-19 vaccines being administered to this age group, and urged healthcare workers to be highly "vigilant" and ensure that only Covaxin is given to individuals in the age group.
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