IN A small study, scientists at Indian Council of Medical Research- National Institute of Virology (NIV) have found that Covaxin offered protection from Delta (B.1.617.2) as well as Beta (B.1.351) variants of SARS-CoV-2, which causes Covid-19.
Scientists decided it was imperative to assess the efficacy of available vaccines against these variants. Researchers evaluated the neutralisation potential of people vaccinated with Covaxin and found that it offers protection against these two variants.
The study carried out by ICMR-NIV and Bharat Biotech was posted on bioRxiv preprint server on June 7. The study, ‘Neutralisation against B.1.351 and B.1.617.2 with sera of Covid-19 recovered cases and vaccinees of BBV152’, however, is yet to be peer reviewed.
Dr Pragya Yadav, scientist ‘E’ and group leader, maximum containment facility, ICMR-NIV, said they had observed a reduction in neutralisation titre values in people vaccinated with Covaxin against Beta and Delta variants, but the reduction was lower than in people who had been naturally infected. Hence, the vaccine does offer protection against these variants, researchers said.
Neutralising antibody titres in the blood closely correlate with the protection provided by effective vaccination. The study checked on the neutralisation potential in people vaccinated with Covaxin and found a three and 2.7 fold reduction in neutralisation titres against the Beta (B.1.351) and Delta (B.1.617.2) variants, respectively. In comparison, the reduction in neutralisation titres with sera from people who had recovered from Covid-19 were 3.3 and 4.6 fold against these variants.
“There was a reduction in the neutralisation titre values in people administered Covaxin, against Beta and Delta variants, but this reduction was lower than in those who were naturally infected,” Dr Yadav said.
The study evaluated the neutralisation potential of sera collected from 20 Covid-recovered cases and 17 people vaccinated with two doses of Covaxin against the Beta and Delta variants and compared it with the prototype D614G variant. This is a small study but a significant one, researchers said. Earlier, NIV scientists studied the neutralisation potential of Covaxin with the B.1, B.11.7, B.1.1.28.2 and B.1.617.1 and found it to be effective against these variants.
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