A study showed that administration of Covaxin booster dose will enhance the vaccine effectiveness against the Delta variant infection and give protection against two Omicron variants of COVID-19.

The study by ‘bioRxiv’, an open-access preprint repository for the biological sciences, shared on Tuesday that its study shows that administration of Covaxin booster dose will enhance the vaccine effectiveness against the Delta variant infection and give protection against the Omicron variants BA.1.1 and BA.2.

The study analysed about the immunity acquired after natural infection or vaccinations against SARS-CoV-2. Vaccine effectiveness also varies with the variant of infection, the study said.

The study compared the protective efficacy of Covaxin following the second and third dose immunizations against the Delta variant and also studied the efficacy of Covaxin against Omicron variants in a ‘Syrian hamster model’.

“The antibody response, clinical observations, viral load reduction and lung disease severity after virus challenge were studied. The protective response in terms of the reduction in lung viral load and lung lesions were observed in both the second dose as well as third doses of Covaxin immunized group when compared to placebo group following the Delta variant challenge,” the study said.

The study further read, “In spite of the comparable neutralizing antibody response against the homologous vaccine strain in both the second dose and third dose immunized groups, considerable reduction in the lung disease severity was observed in the third dose immunized group post-Delta variant challenge indicating the involvement of cell-mediated immune response also in protection.”

“In the vaccine efficacy study against the Omicron variants i.e., BA.1 and BA.2, lesser virus shedding, lung viral load and lung disease severity were observed in the immunized groups in comparison to the placebo groups. The present study shows that administration of COVAXIN booster dose will enhance the vaccine effectiveness against the Delta variant infection and give protection against the Omicron variants BA.1.1 and BA.2,” it concluded.

Phase 3 results of the Covaxin, developed by the Indian Council of Medical Research (ICMR)in partnership with Bharat BiotechInternational Limited (BBIL), has shown an interim vaccine efficacy of 81 per cent in preventing Covid-19.

Covaxin is the first COVID-19 vaccine that has been developed completely in India. On January 16, 2021, India commenced its nationwide vaccination drive.