“The administration of 4th dose might be a considerable approach in vulnerable populations such as immunocompromised patients,” says Dr Rohit Kumar Garg, Consultant, Department of Infectious Diseases, Amrita Hospital, Faridabad.

On a fourth vaccine, he says, “there is very limited data, to suggest any significant benefit against symptomatic infection and severe COVID-19, following administration of 4th dose of available COVID vaccines.”

“Therefore, a more rational approach would be the use of bivalent COVID vaccines (based on old and new strains) for boosting immunity, similar to influenza vaccines (strains updated every season),” explains Dr Garg.