Public health officials are advising social distancing strategies and masks, in part because the latest evidence suggests catching the coronavirus is risky, even if you're young. A significant proportion of COVID-19 survivors experience fatigue, blood clots, fever, and other symptoms for weeks and months after overcoming the infection.Josh Edelson/AFP via Getty Images Hide caption
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Josh Edelson/AFP via Getty Images
Public health officials are advising social distancing strategies and masks, in part because the latest evidence suggests catching the coronavirus is risky, even if you're young. A significant proportion of COVID-19 survivors experience fatigue, blood clots, fever, and other symptoms for weeks and months after overcoming the infection.
Josh Edelson/AFP via Getty Images
As the coronavirus continues to spread rapidly across the United States and beyond, many are wondering: how on earth will this end? In a televised interview this week, President Trump reiterated his belief that sooner or later the virus will burn itself out. "Eventually I'll be right," the president told Fox News host Chris Wallace. "It will go away and I will be right."
However, scientists are increasingly of the opinion that this virus will not go away. In interviews and correspondence with more than a dozen researchers around the world, NPR found that the vast majority believe the virus will persist at some level for a long time to come in places like the US and Europe.
And until there is an effective vaccine that is widely available, immunity will never be high enough to achieve what is calledherd immunity, these researchers say. This is the tipping point where the disease starts to burn itself out because so many people are immune that it can't spread any further.
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These scientists' view that the virus will persist is based on mounting evidence that immunity may not be as straightforward as first thought and that the virus spreads relatively slowly while continuing to make sick and kill. A vaccine could still prevent the disease or reduce its severity, but it's likely that even the COVID-19 won't wipe the globe.
"I think it's probably going to be with us forever at this point," he saysDevi Sridhar, Professor of Global Public Health at the University of Edinburgh. "It's going to stay with us, and so we choose to live with it."
The "take it by the chin" approach
The idea of herd immunity has been around for decades. In the past it was used to describe an effect observed with vaccinations - for example, if vaccination rates for measles are high, a single case cannot spread far into a community. The “herd” of people is protected even if not all have been vaccinated.
But with the outbreak of the corona virus, theIdea of natural herd immunityhas prevailed in some circles. Broadly speaking, the theory is that if enough people get sick and then become immune, the entire population is protected. Estimates vary widely, but it is widely believed that between 50% and 80% of a given population would need to be infected with the coronavirus before such natural herd immunity could be achieved.
Herd immunity is attractive in part because it doesn't require radical measures like social distancing.
"If the most important thing to you isn't disrupting the economy, not shutting down small businesses, not creating economic instability so people can't eat -- that's the solution you're going to go for," he saysJeffrey Schamane, Professor of Environmental Health Sciences at Columbia University in New York City.
For these reasons, the Conservative British government toyed with the idea of herd immunity back in March, says Sridhar. Scientific advisers felt it was futile to try to stop the coronavirus. Instead, some suggested trying to slow infections just enough to avoid overburdening hospitals while allowing the virus to spread through the community. It was the "take it by the chin" approach, ehdescribed by Prime Minister Boris Johnson.
Sridhar says the UK Pandemic Scientific Advisory Group at the time worked from a playbook based on the flu. But COVID-19 is not the flu, and calculations showed that the pursuit of herd immunity would cause many thousands of deaths. The governmentquickly abandoned the strategyalmost as soon as it swam.
Sweden has not closed bars and restaurants during the pandemic. The result has been more cases of coronavirus infection. But far fewer people are immune than it would take for Swedes to achieve herd immunity.Martin von Krogh/Getty Images Hide caption
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Martin von Krogh/Getty Images
Sweden has not closed bars and restaurants during the pandemic. The result has been more cases of coronavirus infection. But far fewer people are immune than it would take for Swedes to achieve herd immunity.
Martin von Krogh/Getty Images
Sweden's experience
Across the North Sea, however, Sweden continued to pursue an approach with the potential to achieve herd immunity - although the government had never stated that as a goal. Swedish authorities recommended precautionary measures be taken at the individual level and banned gatherings of more than 50 people, but the nation stopped closing restaurants and bars. In April the Swedish Ambassadorboasted that Stockholm could achieve herd immunityuntil end of May.
That never happened, says Sridhar. "Sweden has been stuck at 6 percent for months," she says of the percentage of residents who have antibodies to the coronavirus. Meanwhile, the country has suffered from economic devastation and far higher mortality rates than its Nordic neighbors.
She suspects the main reason why herd immunity has not been achieved is that many millions of Swedes would need to get COVID-19 to get there. This could happen in the abstract, but in reality most people consciously try their best to avoid contracting the disease. “No one wants to be part of the herd,” she says.
Sweden is hardly alone. In many countries, blood tests for antibodies - a sign someone has been infected with the coronavirus - find that the percentage of the population testing positive for this indicator of immunity is in the single digits.
“The example I like to think of is South Korea, which currently has 50 cases [of new infections] per day. If they lasted another thousand days, which is three years, they would have 50,000 cases, which is 0.1% of their population," Shaman says.
The US healthcare system would collapse
Even in the US, with 60,000 cases a day, it would take at least 2021 — and possibly years of hospital and morgue-filled hospitals — to infect the required hundreds of millions of Americans.
"I think if you just let that process go, it would be very difficult to predict the number of deaths, but I think we're certainly talking about a million, probably a lot more," says Dr.Josua Schiffer, associate professor in the Division of Vaccines and Infectious Diseases at the Fred Hutchinson Cancer Research Center in Seattle.
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In practice, the US healthcare system would collapse trying to care for so many sick people, says Dr.Nahid Bhadelia, who heads the Special Pathogens Unit at Boston Medical Center. "It's unlikely that we can achieve natural herd immunity without fully depleting the physical and human resources," she tells NPR.
Questions remain about declining immunity and reinfection
However, recent evidence suggests that there is another reason why immunity levels may not rise above a few percent - the protective immunity a person gains after being infected with the coronavirus may fade over time.
An antibody test for the coronavirus can tell if someone has been infected, but it's only a measure of immunity, researchers say. How robust this immunity is and how long it lasts is still an open question.Simon Dawson/AP Hide caption
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Simon Dawson/AP
An antibody test for the coronavirus can tell if someone has been infected, but it's only a measure of immunity, researchers say. How robust this immunity is and how long it lasts is still an open question.
Simon Dawson/AP
TwostudiesNowshowthat coronavirus antibodies, a key aspect of a person's immune response, can disappear in a matter of months. The results are hardly conclusive, and to date there has been no scientific proof of reinfections, but there are precedents.
Shaman says studies his group has done with other common coronaviruses show they can reinfect people. FromTracking infected New Yorkers, Shaman was able to show, for example, that coronaviruses that cause the common cold sometimes reinfected study participants more than once.
"Some of them were separated for four to eight weeks — that's fast, and that could have been a recurrence [of the same infection]," he says. "But others that we know are different — they were eight to 11 months apart."
The coronavirus that causes COVID-19 hasn't been around long enough to cause re-infections in most places, but that could change this fall and winter.
"If it's like other coronaviruses ... we're going to see some of those reinfections over the next six to 12 months," he saysGreta Bauer, an epidemiologist at Western University in Ontario.
Antibodies aren't the only way the immune system uses to fight a disease like COVID-19, and other types of immune cells may be ramping up to quickly fight off infection. But if humans can be easily reinfected, herd immunity just wouldn't work.
"If immunity is only temporary, then the epidemic may not 'end'"Neil Ferguson, a disease modeler at Imperial College London, told NPR in an email. "Rather, we may be seeing a transition from epidemic dynamics to endemic circulation of the virus in the human population, albeit at lower levels."
The conscious pursuit of herd immunity now seems more ethically dubious for elected officials than ever, Bauer says, as individual recovery from COVID-19 also appears to be a lengthy process. A significant proportion of COVID-19 survivors experience fatigue, blood clots, fever, and other symptoms for weeks and months after overcoming the infection.
"We know very little about the long-term effects for people with mild illness," says Bauer. "We don't know if the virus survives in reservoirs in the body, we don't know if it can cause disease later in life, and that's the really hard part for decision-making."
Even if natural herd immunity is achieved, or partially achieved, without a vaccine, it is likely to end up being taken as a sign that a government is not protecting its population. In the US, subgroups of the population -- essential workers, for example -- could be approaching herd immunity, he saysSarah Coby, associate professor and researcher studying pathogens and human immunity at the University of Chicago. But that would be The result of what she describes in an email as a "staggering inability to manage the epidemic -- specifically, to provide the support people need to protect themselves and not infect others."
Nations like Qatar, which have seen huge waves of infection spread by groups of migrant workers, may also soon be nearing herd immunity, Shaman says. "It's a country to watch," he says.
But assuming a vaccine or effective treatments can be developed, Shaman says the world's Qataris will not be seen as winners. Instead, those nations that can safely protect their populations the longest will come out on top. "South Korea, Vietnam, New Zealand, Japan - these will be success stories," he says.
These nations have suppressed the virus through an initial lockdown coupled with continued contact tracing and isolation of sick individuals. This approach, combined with some social distancing and widespread use of masks, may push the virus down to levels where normal life can more or less resume — as long as elected officials, public health leaders, and the public afterward continue to work together to contain any outbreaks.
Sridhar says Scotland is currently pursuing such a "zero-COVID" strategy and while it has not completely eliminated the coronavirus it appears to be working.
"Pubs are open, bars are open, children are playing in the parks," says Sridhar. “Schools will return full-time and infections are low enough for people to feel safe doing. It's a painful process and it takes time, but there are ways you can stop it.”