Bharat Biotech has updated the efficacy of Covaxin to 65.2% against the Delta variant in - Effectiveness Study on Delta Variant - Lancet Infectious Diseases, published on Nov 23 2021.
"Bharat Biotech commends the investigators from the All India Institute of Medical Sciences (AIIMS) on the BBV152 study published in Lancet Infectious Diseases. These results provide evidence for effectiveness for Covaxin in real life settings," Bharat Biotech said.
It added that an effectiveness result of 50% achieved during the peak Covid-19 Delta variant wave in India, in a high risk study population of physicians and health care workers, in a hospital environment, and who are challenged repeatedly with high viral loads, provides insights into the efficacy and effectiveness of Covaxin..
"These results compare well with the 65.2% efficacy against the delta variant obtained during the controlled phase III clinical trials of Covaxin conducted among the general population. This study also shows that Covaxin meets the WHO efficacy criteria for Covid-19 vaccines for the dreaded Delta variant," the company said.
As an independent study by researchers based on real world assessment showed that Bharat Biotech’s Covaxin to be 50 per cent effective against symptomatic Covid-19 disease, experts say more real-world studies are required now. Real-world data, however, shows that vaccines are working against severe disease and hospitalisations, they said. The study, titled “Effectiveness of an inactivated virus-based SARS-CoV-2 vaccine, BBV152, in India: a test-negative, case-control study” assessed 2,714 hospital workers at AIIMS in Delhi, from April 15–May 15, who were symptomatic and underwent RT-PCR test for Covid-19 detection. The results were published in The Lancet Infectious Diseases Journal. Results of an interim study recently published in The Lancet showed that two doses of Bharat Biotech’s Covaxin, also known as BBV152, had 77.8 per cent efficacy against symptomatic disease.
Explaining the difference between the headline efficacy number and the real world analysis on hospital employees, Jacob John, former head of Centre for Advanced Research in Virology at the Indian Council of Medical Research (ICMR) said that Bharat Biotech’s phase-3 trial was done on the general population, while the AIIMS study is on hospital employees who are highly exposed to the virus, especially during a raging second wave.
He added, “The vaccine efficacy against severe disease, hospitalization, ICU admission, or death is almost 100 percent. The 50% efficacy is against symptomatic Covid19 disease. No vaccine in the world is protecting against breakthrough infection. What is important to see is whether it is protecting against severe disease and hospitalizations.”
John feels that vaccines are more effective always after booster shots. The two-dose regimens are the initial dosing, and one needs to start giving booster doses to at least the vulnerable population, he feels.