WHO warns against pursuing herd immunity to stop coronavirus

The World Health Organization on Monday warned against suggestions that herd immunity might be a realistic strategy to stop the coronavirus pandemic, saying such an approach was “simply unethical”. Herd immunity occurs when majority of a population becomes immune to a disease through vaccinations or through the mass spread of a disease.

At a media briefing, WHO Director-General Tedros Adhanom Ghebreyesus said that health officials typically aim to achieve herd immunity via vaccination. He added that to obtain herd immunity from a highly infectious disease such as measles, about 95% of the population must be immunised. Similarly, Tedros said, for polio the threshold is about 80%. The percentage of a population who need be to be vaccinated to reach herd immunity is calculated using the basic reproductive rate (R0).

“Herd immunity is achieved by protecting people from a virus, not by exposing them to it,” the health body chief said. “Never in the history of public health has herd immunity been used as a strategy for responding to an outbreak, let alone a pandemic. It is scientifically and ethically problematic.”