Citing a study on a volunteer who had five Covid-19 jabs, he said the volunteer’s immunity against the virus rose sharply two weeks after receiving the booster before declining.
However, vaccinated people develop mild symptoms and recover from Covid-19 quickly as their “body memory” helps boost immunity once they are infected, Yong made clear.
He said everyone should receive at least three jabs, while at least four should be administered to those with chronic diseases and frontline medical staff so they can deal with virus mutations, especially Omicron.
Yong also advised people to get their next Covid jab four to six months after the third or fourth shots as immunity against the virus drops sharply during that time.
He expected people, especially the vulnerable, would need annual Covid-19 doses, just as in the case of influenza.