Covaxin booster beats back Delta, Omicron variants: NIV

NEW DELHI: A booster dose of Covaxin broadens its efficacy against the Delta variant of SARS-CoV-2 virus and even protects against Omicron variants — BA.1.1 and BA.2— a new study conducted on hamsters by Pune’s National Institute of Virology shows, reports Sushmi Dey.
The researchers compared the efficacy of Covaxin after the second and third doses against the Delta variant, and also studied its efficacy against the Omicron variants in a Syrian hamster model.

“Protective response in terms of the reduction in lung viral load and lung lesions were observed in both the second as well as third dose of Covaxin immunised group when compared to placebo group following the Delta variant challenge. In spite of the comparable neutralising antibody response against the homologous vaccine strain in both the dose 2 and dose 3, considerable reduction in the lung disease severity was observed in the third dose immunised group post Delta variant challenge, indicating the involvement of cell mediated immune response also in protection,” the paper, published in bioRxiv, a pre-print server, said. The study has not yet been peer reviewed. “In the vaccine efficacy study against the Omicron variants BA.1 and BA.2, lesser virus shedding, lung viral load and lung disease severity were observed in the immunised groups in comparison to the placebo groups,” it added.