Can Herd Immunity Save Us?

Soon after the novel coronavirus emerged as a global threat this spring, certain terms usually confined to public health and epidemiology — like “flatten the curve” and “PPE” — became part of our everyday vocabulary. Among them is “herd immunity,” which some people, including Donald Trump, have said will eventually bring the pandemic to a close, even without a vaccine. But unlike “social distancing” — which is a relatively easy concept for most people to understand — “herd immunity” is more complex, especially since there’s more than one way to achieve it.  

If you’re someone who has managed to coast through the pandemic dropping “herd immunity” into conversations, but never fully knowing what it means, now’s the time to fix that. That’s because since October 4th, a proposal from a group of scientists backed by a libertarian think tank advocating for reaching herd immunity through uncontrolled spread of Covid-19 — known as the Great Barrington Declaration — has caught the attention of scientists and government officials around the world, including the president. In the process, the conversations surrounding the declaration have further ignited the debate on reopening society, and its cost in human lives. Here’s what you need to know about herd immunity, and whether it’s a feasible way of slowing, and eventually stopping, Covid-19.

What is herd immunity?

Herd immunity refers to the point at which there are enough members of a community with individual immunity to an infection — which they’ve gotten either by naturally contracting and then recovering from the illness, or through vaccination — that those who remain unvaccinated are protected from an outbreak. “Individuals could still become infected, but they would not continue to spread it to others because they’d be sufficiently surrounded by immune people,” says Dr. Howard P. Forman, professor of radiology and public health, as well as director of the health care management program at the Yale School of Public Health, and one of the leading voices on herd immunity. “It would not protect the individual, per se, but it protects the group from a new outbreak.”

According to Dr. Robert Salata, an infectious disease specialist and program director of the Roe Green Center for Global Health & Medicine at University Hospitals in Cleveland, herd immunity is achieved when 45 to 70 percent of a general population have developed antibodies to a particular virus, which, in turn, should provide widespread protection against the infection. 

Herd immunity is the end goal of developing a vaccine, Forman explains. But when government officials talk about relying on “herd immunity” as a strategy for slowing and eventually stopping the Covid-19 pandemic without a vaccine, it’s a more dangerous approach. Instead of waiting for a safe and effective vaccine, it involves reopening schools and businesses so that the virus has the opportunity to make its way through the population naturally — causing a rising death toll in the process — until there are enough individuals with immunity to protect the community from another outbreak. The latter is the basis of the Great Barrington Declaration.

What is the Great Barrington Declaration?

While this isn’t the first time achieving herd immunity through uncontrolled transmission of Covid has been suggested during the pandemic, the Great Barrington Declaration stands out because it was developed by a seemingly trustworthy source: three epidemiologists from Harvard, Oxford, and Stanford Universities. So far, more than 30,000 medical practitioners and 11,000 “medical and public health scientists” have signed the declaration.

Specifically, the Great Barrington Declaration calls for immediately permitting people to resume their pre-pandemic lives if they’re not especially vulnerable to Covid-19. “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 reads. “We call this Focused Protection.”

But the declaration has faced backlash. More than 6,400 scientists, researchers, and healthcare professionals have signed a memorandum denouncing herd immunity through uncontrolled transmission as “a dangerous fallacy unsupported by scientific evidence.” Dr. William Hanage, associate professor of epidemiology at Harvard University’s T.H. Chan’s School of Public Health, is one of the signatories and says that the declaration leaves out a lot of crucial information. This includes the difference between achieving herd immunity through a vaccine versus uncontrolled transmission, and any clues as to how “focused protection” would be achieved. Similarly, it highlights the harms of “lockdowns,” saying that they produce “devastating effects on short and long-term public health,” but never actually explain what they mean by a “lockdown” in terms of length or the types of restrictions. 

Can this herd immunity strategy be safe and effective at this point in the pandemic?

According to Forman, Hanage, and thousands of other medical researchers and practitioners, the answer is a resounding no. “These are very bright people, who seemingly live in a different world,” Forman says of the epidemiologists behind the Great Barrington Declaration.. “Their notion that somehow we could segment off all of the vulnerable populations and let everyone else get infected seems incredibly naive.” 

In fact, Forman says that if we were to achieve herd immunity through infection in the United States, it would result in more than one million premature deaths. “Attempting to attain [this type of herd immunity] is actually saying ‘yes’ to uncontrolled transmission,” Hanage tells Rolling Stone. “The consequences of infection are worst for older folks, but are much more dangerous for younger people than any vaccine that would ever be licensed.” 

Not to mention that younger people are dying, too. On October 23rd, the Centers for Disease Control reported that so far this year, there have already been approximately 300,000 more deaths in the U.S. than would be expected. The age group with the largest percentage increase? People between the ages of 25 and 44. At the final presidential debate last week, Trump reinforced the fallacy that the virus is only harmful to older adults, when he claimed that “99.9 percent of young people” recover from Covid-19. But that is categorically untrue. Research published in September in the journal JAMA Internal Medicine, indicated that 21 percent of people between the ages of 18 and 34 that had been hospitalized for Covid required intensive care, while 10 percent required mechanical ventilation, and nearly 3 percent died.

But surviving and fully recovering from Covid-19 or dying from it aren’t the only two outcomes: There are also the tens of thousands of Americans who are Covid long-termers. At this point, it’s unclear whether, after months of symptoms — some of which may result in serious chronic health problems like cardiovascular conditions or rheumatoid arthritis — long-termers will ever recover from the virus. “It’s understandable that we focus on deaths,” Hanage explains. “But there are a lot of people in all age groups suffering for months from the virus — even among a large proportion of people with mild cases [of Covid-19]. The long-term consequences aren’t yet known.”

What is the Trump administration’s stance on herd immunity?

Though the White House recently embraced the Great Barrington Declaration, Trump was not initially on board with this type of herd immunity. Back in April, he criticized the Swedish government’s approach to handling Covid-19, which he incorrectly claimed involved a herd immunity strategy. Meanwhile, Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, has been consistently opposed to the idea of reaching herd immunity through uncontrolled transmission, including calling it “total nonsense” during an October 15th interview on Good Morning America.

But by September, Trump had evidently changed his mind, when, in a town hall event moderated by George Stephanopoulos, Trump said that Covid-19 would go away “over a period of time,” even without a vaccine. He continued: “You’ll develop herd — like a herd mentality. It’s going to be herd-developed, and that’s going to happen. That will all happen.” Malapropism aside, it appears as though these views on herd immunity are something Trump picked up from his newest Covid-19 adviser, Dr. Scott Atlas: a radiologist with no previous experience in epidemiology, infectious diseases, or health policy, and herd immunity enthusiast

Meanwhile, back in the spring, Atlas bonded with one of his colleagues at Stanford — an epidemiologist named Dr. Jay Bhattacharya — over their mutual opposition to lockdowns and belief that restrictions of this type would do more harm than good when it came to the economy. Bhattacharya is one of the three scientists who wrote the Great Barrington Declaration. As soon as the document was made public, Atlas invited Bhattacharya and his co-authors to D.C., and gave them the opportunity to present their proposal to Secretary of Health and Human Services Alex M. Azar II, the New York Times reports

And though Atlas, Azar, and other members of the Trump administration have routinely denied any plans to implement an uncontrolled-transmission herd immunity approach, that hasn’t stopped them from tweeting their support of the policies laid out in the Great Barrington Declaration. “The [Trump] administration has danced around the idea that we need to get herd immunity from having infections,” Forman explains. And when members do talk about herd immunity, he says, it’s in the context of having a specific number of relatively younger and healthier people get Covid — but not so sick that they would die. 

The goal of this type of approach would be to reach the same levels of immunity that would be achieved through immunization, but without the wait for a vaccine in order to get the economy moving again. “There are obviously many reasons why that’s a false premise,” Forman says, “not least of which is that it’s very difficult to infect young, healthy people, without also infecting older, vulnerable individuals.” 

Has this type of herd immunity ever been successful?

In short, no. According to Forman, there has never been a deliberate attempt to reach herd immunity through uncontrolled transmission, rather than a vaccine. “There is no example of any community making the decision: ‘let’s just get everybody infected and then we won’t have to deal with it anymore,’” he explains. “The problem with this logic is that this has never been tried purposefully before, let alone has it ever succeeded.” 

Previously, some pointed to what happened in Manaus, a city in Brazil’s Amazon —  which saw a sudden, rapid surge in Covid-19 cases, hospitalizations and deaths (to the point where cemeteries couldn’t keep up) in the late spring — as an example of herd immunity being achieved. Deaths plummeted in June and continued to do so throughout the summer, but starting in September, the number of cases once again began to rise. So despite the fact that 66% of the population of Manaus had been infected by SARS-CoV-2 by the end of the first wave, it wasn’t enough to reach the point of herd immunity. 

Is there a more effective approach to ending the coronavirus outbreak?

As a matter of fact, there is, according to Hanage: pandemic management. “It can take many forms, but when you see countries as diverse as Japan, Vietnam, Germany, Norway, Australia and New Zealand managing to avoid large surges, there are clearly many possible approaches,” he says. For example, Japan is a high-mask-use society, and also began putting in place interventions targeting clusters of transmission early in the pandemic. If enough people avoid the “three Cs” — close contact, closed ventilated spaces, and crowds — it is expected to slow the viral spread, Hanage explains.

Another aspect of pandemic management involves focusing on resources instead of restrictions. “Give people sick pay so they can take time off work when they are sick, or even better, when they’ve been exposed to a known case,” Hanage says. “Milder interventions [put in place] earlier are better than draconian ones too late. Invest in rapid testing of large numbers of the population, isolating those who are positive.” Alternatively, if you are lucky enough to live in a place that has managed to get transmission down to very low levels, he says that it’s possible to safely reopen, as long as there is aggressive contact tracing and rapid responses to future flare-ups.

The bottom line: Nobody wants a lockdown

Like so many other aspects of the pandemic, the idea of herd immunity has also been politicized, thanks in part to the perceived economic implications of lockdowns. Somehow, the debate has been reduced to “pro-lockdown” (herd immunity through vaccination) versus “anti-lockdown” (herd immunity through uncontrolled spread) — but that is entirely inaccurate. Nobody wants another lockdown.

According to Hanage, epidemiologists like himself, who are opposed to a herd immunity strategy involving uncontrolled transmission, are actively trying to avoid another lockdown by working to get the spread of Covid-19 under control. Meanwhile, “seeking immunity through uncontrolled transmission is the quickest route to a lockdown,” he says. Ultimately, everyone wants the same result: ending the Covid-19 pandemic. The difference lies in how we get there, and how many lives are lost or irreparably damaged along the way.

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