Subunit vaccines better choice for boosters: WHO expert | India News

Subunit vaccines better choice for boosters: WHO expert | India News

HYDERABAD: Days after India announced its booster policy, a top health expert has said efficacy of existing vaccines may decline against Omicron but remain robust against severe disease. Protein subunit vaccines could be better choice for boosters.
Sharing how both Covaxin and Covishield behaved against Delta, Dr Anurag Agrawal, chair of WHO’s Technical Advisory Group on SARSCoV-2, said those data gave some indication on how the existing vaccines may behave against Omicron. He said based on the limited data available, he expects protein subunit vaccines to be the better choice for boosters.
Subunit vaccines contain fragments of protein from the pathogen, to help produce an effective immune response. Scientists say such vaccines with lesser side-effects can be administered to a large group, including ones with chronic health conditions. He said prior to the Delta attack, efficacy of Covaxin and Covishield was apparently similar at about 75% to 80% for infections and about 90% for severe disease.
“In Indian healthcare workers, pre-prints and full publications from ICMR and AIIMS have shown that Covaxin remained effective during the Delta wave, but with lower efficacy than previously reported. It was around 50% for infections, and 70% for severe disease,” Dr Agrawal, also director of Institute of Genomics and Integrative Biology (CSIR), told TOI.
“In the same ICMR-AIIMS study, Covishield’s effectiveness against severe disease was about 80%. The protection against infection in other healthcare worker studies varied but was typically around 60%,” he added.
Global data for other whole inactivated virus vaccines versus those that target the spike protein, showed the latter fared better, he said. “One should assume that Covaxin’s efficacy against infection will decline sharply against Omicron, but will remain high for severe disease,” Dr Agrawal said.
To tackle Omicron, the immune response needs to be very strong and can be reached either through hybrid immunity, with infection plus vaccination, or by boosters, Dr Agrawal said.

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