Vaccine maker Bharat Biotech has not provided any data on the efficacy of the Covaxin jab against the Omicron variant of coronavirus in a study on its booster doses published on Saturday.
This is despite the fact that from Monday, a booster shot of Covaxin will be administered as a “precaution dose” to citizens over 60 years with co-morbidities who have received two doses of the vaccine earlier. Covaxin is also the only vaccine that is being used in the inoculation drive for children in the age group of 15 to 18.
Bharat Biotech’s study, however, claims that the third dose of the Covaxin jab results in a 19 to 265-fold increase of antibodies in a person’s body against the original strain of the Covid-19 virus and other variants like Alpha, Beta and Delta.
Participants in the study, which has not been peer-reviewed yet, received a booster dose of Covaxin six months after they were administered the second dose of the vaccine. The researchers said that while protection against severe disease remained high for six months after the second dose, they noted a decline in the efficacy against symptomatic cases over time and the continued emergence of variants was expected.
However, a booster dose of the vaccine resulted in a “pronounced increase” of T-cell and B-cell responses against the virus, which showed that the third shot of Covaxin could offer “long term protective efficacy” against severe cases of coronavirus, the researchers said.
T-cells and B-cells are types of white blood cells that determine the immune response in a person’s body against antigens, or foreign substances.
“These trial results provide a strong foundation towards our goal to provide Covaxin as a booster dose,” Krishna Ella, the chairman and managing director of Bharat Biotech said.
Covaxin has been used in India since India began its immunisation drive on January 16. The vaccine, however, received the World Health Organization’s approval only on November 3. Phase 3 trial results published by Bharat Biotech in November showed that the two-dose regimen of the vaccine had an overall efficacy of 77.8% in symptomatic Covid-19 patients.