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“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’s scientifically and ethically problematic,” Dr. Tedros said.
The WHO estimates that about 10% of the world has contracted the coronavirus. It is not yet known what percentage rate of infection is needed to achieve herd immunity.
Tedros noted that to obtain herd immunity from measles, about 95% of the population must be vaccinated, while for polio, the threshold is about 80%.