Citing foreign research, he said that people who had already been infected with Covid-19 were 84 per cent free from the virus compared to those who had never been infected.
"To put it simply, immunity built from the Covid-19 infection or vaccine made from the virus has 84 per cent efficacy in preventing infection," he said.
"Immunity cannot be 100 per cent for Covid-19, unlike measles and chickenpox," he said, adding that vaccines with 84 per cent efficacy are considered effective in the case of Covid-19.
"In the future, people may have to receive more jabs to stimulate immunity for long-term prevention," he said.
He added that even people who have been infected with Covid-19 would need vaccination just as those who have never been infected.
"This would be a great opportunity for vaccine manufacturers," he added.