Covaxin 50 pc effective against symptomatic COVID: Lancet study

The study published in Tuesday night is indicating reduced effectiveness of two doses of Covaxin against SARS-CoV-2 infections that are attributed to the delta variant

Hyderabad: A new study published in the noted peer reviewed journal The Lancet has indicated that effectiveness of Covaxin, the Covid vaccine manufactured by Hyderabad-based Bharat Biotech, is 50 percent against all the delta variants of SARS-CoV-2. The study published in Tuesday night is indicating reduced effectiveness of two doses of Covaxin against SARS-CoV-2 infections that are attributed to the delta variant, which is considered to be a major cause behind the surge in the second Covid wave.

The evaluation of Covaxin was carried out on Covid-19 positive patients during the second wave of the pandemic between April 15, 2021 and May 15, 2021 by clinicians and researchers of All Indian Institute of Medical Sciences (AIIMS), New Delhi.

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“We aimed to evaluate the effectiveness of BBV152 (Covaxin) against symptomatic RT-PCR-confirmed SARS-CoV-2 infection. The effectiveness of BBV152 against symptomatic Covid-19 after two doses administered at least 14 days before testing was 50 percent. The effectiveness of two doses administered at least 28 days before testing was 46 percent and administered at least 42 days before testing was 57 percent,” the AIIMS study in The Lancet, said.

The decline in vaccine effectiveness against SARS-CoV-2 infection during a delta-driven surge in cases is neither surprising nor exclusive to inactivated SARS-CoV-2 vaccines including BBV152 (Covaxin). The delta variant has high transmissibility, infectivity, and virulence, which causes severe disease. These attributes might have contributed to a reduced vaccine effectiveness against symptomatic infections,” commenting on the study in The Lancet, T Ramachandran from Translational Health Science and Technology Institute, Faridabad, said.

“It is important to note that the vaccine effectiveness estimated was not against delta variant infections only, but against infections that occurred during the surge in SARS-CoV-2 cases dominated by the delta variant,” Ramachandran and other researchers from Translational Health Science and Technology Institute, Faridabad, in their comment on the study, said.

Furthermore, the study was conducted in a high-risk population with a high exposure to SARS-CoV-2 in a tertiary care hospital caring for patients with Covid-19, in the context of a massive surge in infections, with high test-positivity rates of up to 34  percent, which could have been the key factor for the observed reduction in vaccine effectiveness,” the experts concluded.