The science behind Covid-19 vaccine boosters: Do we really need an extra shot?

A man getting a Covid-19 vaccine booster jab at Teck Ghee Community Club on Sept 15, 2021. - ST FILE

SINGAPORE (The Straits Times/Asia News Network): It was only earlier this year that "Have you been vaccinated?" became the standard greeting in many countries. Now, that is set to be taken over by: "Have you got your booster shot?"

Some countries, including Singapore, Israel, Germany and France, have started administering an additional dose of a Covid-19 vaccine to the elderly and the immunocompromised, as studies show waning immunity against the coronavirus over time after the initial shots.