Herd immunity is typically achieved with vaccination and most scientists estimate at least 70% of the population must have antibodies to prevent an outbreak. But some experts have suggested that even if half the population had immunity, there might be a protective effect.
WHO’s emergencies chief Dr. Michael Ryan largely dismissed that theory at a press briefing on Tuesday, saying we should not live “in hope” of achieving herd immunity.
“As a global population, we are nowhere close to the levels of immunity required to stop this disease transmitting,” he said. “This is not a solution and not a solution we should be looking to.”
Most studies conducted to date have suggested only about 10% to 20% of people have antibodies.
Dr. Bruce Aylward, a senior adviser to WHO’s director general, added that any mass immunization campaign with a COVID-19 vaccine would aim to cover far more than 50% of the world’s population.
“We don’t want to be wrong,” he said. “You want to plan to get high coverage and not get lulled into a dangerously seductive suggestion that [the herd immunity threshold] could be low.”