PremiumPhase 3 results of the Covaxin, developed by the Indian Council of Medical Research (ICMR)in partnership with Bharat Biotech International Limited (BBIL), have shown an interim vaccine efficacy of 81% in preventing Covid-19
Listen to this article |
The administration of a Covaxin booster dose enhances the vaccine effectiveness against the Delta variant and two sub-strains of the Omicron variant, a new study has revealed.
The study was conducted by 'bioRxiv', an open-access preprint repository for the biological sciences and shared on Tuesday. It analysed the immunity acquired after natural infection and that after getting vaccinated against SARS-CoV-2.
The researchers compared the protective efficacy of Covaxin following the second and third dose immunisations against the Delta variant and also studied the efficacy of Covaxin against Omicron variants in a 'Syrian hamster model'.
It was revealed that vaccine effectiveness also varies with the variant of infection.
"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.
“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," it added.
It went on to say that 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 evidence from the present study shows that Covaxin booster immunisation tends to broaden the protective immune response and reduces disease severity against the Delta and Omicron variant infection," it said.
Phase 3 results of the Covaxin, developed by the Indian Council of Medical Research (ICMR)in partnership with Bharat Biotech International Limited (BBIL), have shown an interim vaccine efficacy of 81% in preventing Covid-19.
