Covishield vaccine remained effective even during India’s second wave

Vaccine efficacy in double jabbed individuals stood at 63 per cent, according to The Lancet

The Covishield vaccine was effective against coronavirus infections when the pandemic, driven by the delta variant, was at its peak in India, according to a recent study published in The Lancet journal.

The study evaluated the effectiveness of Covishield against the delta variant, and was conducted between April and May this year, when India was recording up to 300,000 cases of Covid-19 a day.

Covishield is the locally manufactured version of the Oxford-AstraZeneca vaccine being used in the UK and other countries. It is made by the Serum Institute of India, and is the most used vaccine in the country.

“The ChAdOx1 nCoV-19 [Covishield] vaccine remained effective against moderate-to-severe Covid-19, even during a surge that was dominated by the highly transmissible delta variant of SARS-CoV-2,” the paper concluded.

The study was done at two medical research centres in Faridabad in northern India’s Haryana state, and found the vaccine effectiveness to be 63 per cent among fully vaccinated individuals. During the moderate-to-severe disease phase, the effectiveness was 81 per cent.

Among those who had only received a single dose, the vaccine effectiveness was 46 per cent, and it increased to 79 percent during the moderate-to-severe disease phase.

“Our data suggest that two doses of the ChAdOx1 nCoV-19 vaccine provide modest protection against infection with the SARS-CoV-2 delta variant and high levels of protection against moderate-to-severe Covid-19,” said the researchers.

So far, 81% of India’s adults have received at least one dose while 43% have had two doses. Vaccination for people under 18 has not yet begun.

Nearly 400,000 people died in India during the country’s devastating second wave, according to very conservative government figures. However, according to several other studies, the death toll is expected to be at least ten times higher.

The findings also come amid the discovery of new variant omicron, which has prompted public concern around the world and sent scientists racing to examine its potential impact.

So far, more than 150 infections of the omicron variant have been detected in over a dozen countries across the world, with the highest number — 77 cases — reported in South Africa.

The heavily mutated variant, whose scientific name is B.1.1529, poses a “very high risk” of infection and is likely to spread internationally, bringing potentially “severe consequences” for some communities, the World Health Organisation said on Monday.