Tedros Adhanom Ghebreyesus cautioned against some countries’ decision to allow the novel virus to run its course until enough people develop the immunity needed to naturally halt its spread.
"Herd immunity is a concept used for vaccination, in which a population can be protected from a certain virus if a threshold of vaccination is reached," the WHO Chief pointed out during a virtual press briefing.
For measles, for instance, it is estimated that if 95 percent of the population is vaccinated, the remaining five percent will also be protected from the spread of the virus.
For polio, the threshold is estimated at 80 percent.
"Herd immunity is achieved by protecting people from a virus, not by exposing them to it," WHO's Tedros 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," he insisted.
The new coronavirus has killed well over one million people and infected more than 37.5 million since it first surfaced in China late last year.