GENEVA, Switzerland (AP) — Scientists at the World Health Organization estimate that about 60 to 70 per cent of people in countries will need to be vaccinated against the coronavirus to achieve any type of herd immunity.

At a press briefing on Friday, WHO vaccines expert Dr Kate O’Brien said it was still unclear if vaccines against COVID-19 might reduce the amount of time people are infectious or their ability to spread the virus. But she said modelling studies suggest up to 70 per cent of the population will need to be immunised so that people are protected from the disease.

“It’s really important that we actually start to get more information about what the vaccines do, not just for preventing disease, but for actually preventing the acquisition of the virus,” said O’Brien, director of the UN health agency’s department of immunization, vaccines and biologicals.

Dr Michael Ryan, WHO’s emergencies chief, noted that in some situations, targeting certain groups for vaccination may be more important than immunising the entire population.

“We’ve seen in many clusters that only 20 per cent of the cases go on to transmit to others, 80 per cent don’t transmit to anybody else,” he said. “I think we’ll need to be much more surgical and precise in exactly who we target for vaccination. It may be much more important to target certain sections of the community.”