- Herd immunity is necessary to really contain a virus, according to epidemiologists.
- That is generally achieved once enough people either get vaccinated or survive the virus so they have the antibodies to fight off new infections and the virus doesn't have enough new hosts to spread.
- Most scientists think 60% to 80% of the population needs to be immune to achieve herd immunity, the WHO said.
The World Health Organization on Wednesday advised public officials against trying to achieve so-called herd immunity to the coronavirus by allowing it to rapidly spread throughout their communities, saying it will overwhelm hospitals and kill a lot of people.
Herd immunity is necessary to really contain a virus, according to epidemiologists. That is generally achieved once enough people either get vaccinated or survive the virus so they have the antibodies to fight off new infections and the virus doesn't have enough new hosts to spread.
Most scientists think 60% to 80% of the population needs to be vaccinated or have natural antibodies to achieve herd immunity, Mike Ryan, executive director of the WHO's health emergencies program, said on a live Q&A streamed across multiple social media platforms. "Whatever that number is, we're nowhere near close to it, which means this virus has a long way to burn in our communities before we ever reach that," he added.
Simply waiting for herd immunity to happen by allowing the virus to spread, as some opponents of social distancing measures have suggested, is dangerous, he added.
"The idea that we would have herd immunity as an objective, in some sense, it goes against controlling the disease because if you were to say, 'We need to have a herd immunity of 70% and we should let the virus spread until we get to 70%,' we've seen what happens," he said. "Hospitals get overwhelmed. A lot of people die."
Even if people don't die from the disease, there are still long-term problems, Ryan said. "Anyone who looks at patients who are severe with Covid realizes this is a very severe, multiorgan disease that stresses many systems in the body, the cardiovascular system, the neurologic system. And we have to assume in milder cases a similar process is happening at a milder level."
Young people with Covid-19 have left hospitals healthy, only to experience problems 10 or 15 weeks later, he said.
"They can't run. They can't exercise, they are out of breath, having coughing fits," he said. "Who wants or needs that?"
The coronavirus has a wide range of symptoms, according to infectious disease experts and doctors who treat patients. Some people can be asymptomatic, where they never develop symptoms, while others get mild symptoms or severe symptoms that require hospitalization and even intensive care.
"We have to come to grips that Covid might kill me but it could also debilitate you over a significant period of time. And therefore we have to take it seriously. We have to take protecting ourselves and protecting others seriously," he said. "At some level, we have the right to potentially risk harm to ourselves. We have no right to risk harm to others."
The comments come as the coronavirus has spread to more than 16 million people worldwide and killed at least 660,881, according to data compiled by Johns Hopkins University. That's nowhere near the levels needed to slow transmission, experts say.
Last week, Dr. Anthony Fauci, the nation's leading infectious disease expert, said it is unlikely the coronavirus will ever be eradicated.
While the virus may not totally disappear, it's possible world leaders and public health officials could work to bring the virus down to "low levels," he told the TB Alliance.
"I think with a combination of good public health measures, a degree of global herd immunity and a good vaccine, which I do hope and feel cautiously optimistic that we will get, I think when we put all three of those together, we will get control of this, whether it's this year or next year. I'm not certain," he said.
But, he added, "I don't really see us eradicating it."