Covishield vaccine remained effective amid surge of Delta variant, shows Lancet Study

Pune-based Serum Institute of India's Covishield vaccine remained effective against moderate-to-severe COVID-19 infection even amid the second wave, which was led by the highly transmissible Delta variant, revealed a study published in journal 'The Lancet Infectious Diseases'.

As part of the Lancet study, a multi-institutional team of Indian researchers led by Translational Health Science and Technology Institute (THSTI) evaluated the real-world vaccine effectiveness of Covishield during the coronavirus infection surge between April and May, 2021, in India.

The researchers assessed neutralising activity and cellular immune responses against the variants in healthy vaccinated persons to understand the mechanisms of protection. The study included a comparison between 2,379 cases of confirmed coronavirus infection and 1,981 controls

The Covishield vaccine effectiveness against SARS-CoV-2 infection in fully vaccinated individuals was found to be 63 per cent. The vaccine effectiveness of complete vaccination against moderate-to-severe disease was much higher at 81 per cent, according to the study.

The study has been published amid rising concern of a new variant - Omicron - which was first detected in South Africa last week. The World Health Organisation (WHO) designated SARS-CoV-2 variant B.1.1529 as a 'variant of concern'.

The new variant has been labelled by scientists to be far more virulent than the Delta strain that battered India during the second wave of the pandemic. It is expected to have an alarmingly high number of mutations that might make Omicron more resistant to vaccines, induce more severe symptoms, and increase transmissibility.

In an effort to contain the new variant, several countries have already imposed travel bans,  especially for those coming from countries in southern Africa.

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