The idea that the public can infect its way out of the COVID-19 pandemic is “a dangerous fallacy unsupported by the scientific evidence,” 80 researchers said Wednesday in a letter published in the Lancet.
They strongly denounced the idea, advocated by the White House, of achieving “herd immunity” against the virus that causes the disease by letting healthy people with a low risk of serious illness get infected.
A community is considered to have herd immunity when enough people have built up protection against a pathogen, either through natural infection or a vaccine. For extremely contagious viruses like the measles, about 90% of the population must be protected to prevent transmission.
No one knows exactly how many people need to be protected to stop COVID-19 from spreading, but estimates range from 50-70% of the population. Current estimates put that percentage based on those who’ve been infected in the U.S. at about 10%.
The U.S. now reports more than 7.8 million cases and more than 216,000 deaths, according to Johns Hopkins data. Five states had a record number of deaths in a week, and 12 states set records for new cases in a week, a USA TODAY analysis found.
A memorandum published Oct. 4, called the Great Barrington Declaration, called for the world to embrace herd immunity for COVID-19 as a way to protect the vulnerable while still allowing economies to thrive.
The declaration came out of a meeting hosted by the libertarian-leaning American Institute for Economic Research. Its website says it has more than 9,000 signatures, though most names are not public.
“The most compassionate approach that balances the risks and benefits of reaching herd immunity, is to allow those who are at minimal risk of death to live their lives normally to build up immunity to the virus through natural infection, while better protecting those who are at highest risk,” the declaration says.
On a call with reporters on Monday, a senior administration official said the president has long supported the same idea. “The plan is endorsing what the President’s policy has been for months,” he said.
But the idea leaves most epidemiologists both appalled and incredulous.
“It’s just ridiculous,” said Dr. Yvonne Maldonado, an epidemiologist and infectious disease specialist at Stanford University Medical School. “Everything they say (in the declaration) is either misinformation or an outright lie.” she said.
The president of the Infectious Diseases Society of America, Dr. Thomas File, denounced the declaration Wednesday, saying it was “released without data or evidence.”
Not the way to end a pandemic
Herd immunity can’t work for several reasons, Maldonado said. First, no one yet knows how long someone who’s had COVID-19 remains immune.
“We know that the natural history of coronavirus infections is that people can get reinfected over and over again,” she said. In one recent, well documented case, a 25-year-old man from Nevada was infected in late March and five weeks after recovering was diagnosed again with a slightly different version of the virus.
The idea that it’s even possible to isolate high-risk people also is absurd, she said.
“Over 40% of the U.S. population has some risk. I don’t know how you are going to keep 40% of the population away from the other 60%,” she said.
Finally, while younger people are at “minimal risk of death,” as the declaration reads, it’s by no means a zero chance.
Trying to reach herd immunity would result in a much higher death rate than the United States is already experiencing, which is why the concept is not being seriously discussed in scientific circles, said George Rutherford, an infectious disease specialist at the University of California, San Francisco.
“What we’re talking about here is a disease in which you probably need to get somewhere in excess of 60% of people with permanent — not temporary — immunity, he said. “It’s just not attainable without a much greater mortality than we’ve had so far.”
Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, told a college class at the Massachusetts Institute of Technology last month that it’s not clear what percent of the population would need to be infected to provide herd immunity to COVID-19, though it’s expected to be between 50% and 75% of the public.
“We’re not anywhere near there yet,” he said. “If already, 200,000 people have died and you want to let things go to get herd immunity, you’re going to get a lot of suffering and a lot of deaths. If we get herd immunity, let’s get it with a vaccine, and not by letting everybody get infected.”
Already the United States accounts for about 4% of the world’s population but has suffered 20% of the confirmed COVID-19 deaths.
In addition to those killed by COVID-19, the diseasealso leaves many people withlong-term health impacts that are still not fully understood.
Even heavily infected areas are seeing increases
If high rates of infection meant fewer people would get sick, then New York City would be seeing low COVID-19 rates now. That’s not what’s happening, said Stephen Kissler, a research fellow in the Department of Immunology and Infectious Diseases at Harvard T.H. Chan School of Public Health.
“It is crystal clear that there are still enough susceptible people in the population even in major parts of New York City to sustain outbreaks,” he said. “What we do see are vast differences in people’s responses to the pandemic and the precautions people are taking.”
People in New York are now socially distancing, wearing masks and taking other precautions, he said.
By definition, at the point at which herd immunity is reached, infections should decline of their own accord. But even in the hardest hit areas of New York, where somewhere between one-quarter and one-third of residents are believed to have been infected in the spring, infection rates are currently rising.
“That’s the only thing you need to know that herd immunity has not been reached,” said William Hanage, a Harvard epidemiologist.
There’s a better way
Critics say instead of pushing for herd immunity, the Trump administration should be promoting public health measures known to be both safe and effective: wearing masks, washing hands, avoiding large groups, maintaining social distancing, and providing easily accessible testing and contact tracing.
The Lancet letter, called the “John Snow Memorandum,” notes countries that have mounted a robust public health response to the virus, including Japan, Vietnam and New Zealand, have effectively controlled transmission.
“We cannot afford distractions that undermine an effective response,” said the 80 signatories, who make up a Who’s Who of the epidemiological, infectious disease and vaccinology world. They invited others to sign as well.
Dr. John Snow was a Victorian physician considered the father of epidemiology. He famously tracked the source of a London cholera epidemic to a contaminated water well in 1854. He removed the pump handle so no one could get water from the well — a controversial move at the time — and the epidemic ended.
On Monday, World Health Organization head Tedros Adhanom Ghebreyesus called the idea of a society attempting to protect itself by herd immunity not just unscientific but also unacceptable.
“It’s not a choice between letting the virus run free and shutting down our societies,” he said.
Herd immunity, Ghebreyesus said, is only possible through vaccination, which safely protects a large enough portion of the population to keep the virus from spreading. Letting the virus circulate unchecked would mean unnecessary infections, suffering and death.
Stopping COVID-19 doesn’t require countries to shut down but to apply simple and inexpensive public health tools, he 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,” Ghebreyesus said. “Allowing a dangerous virus that we don’t fully understand to run free is simply unethical.”
Karen Weintraub also contributed to this report.
Contact Elizabeth Weise at eweise@usatoday.com.
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