Too early to say if COVID-19 booster shots will be needed: WHO Chief Scientist

"Data from countries introducing precautionary extra inoculations later this year—particularly for vulnerable people whose immunity to SARS-CoV-2 may wane faster—will inform WHO’s guidance," she was quoted as saying.

Read | We’ll probably need booster shots for COVID-19. But when? And which ones?

On the mixing vaccines, Swaminathan said that early data from the UK, Spain and Germany suggested that using two different types of jabs generated more pain, fever and other minor side effects in comparison to two doses of the same vaccine.

"However, the so-called heterologous prime-boost combinations appear to spur a more robust immune response, leading to both higher levels of virus-blocking antibodies and the white blood cells that kill virus-infected cells," she added.

The discourse around booster shots has gathered steam as the highly transmissible variants such as Delta, first reported in India, continue to lead a surge in COVID-19 infections in multiple countries.

Studies are on to see whether a booster shot will increase antibodies and prolong protection against the virus.

Although many scientists estimate that the protection from vaccines will last at least a year, no one knows for sure. It is also unclear whether emerging variants of the coronavirus will change vaccination needs.

Click here for Moneycontrol's full coverage of COVID-19