Health

6 Myths About Coronavirus Herd Immunity, Debunked By Doctors

Maybe don’t believe what your uncle’s posting on Facebook.

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Early in the coronavirus pandemic, people wondered if herd immunity might make it safe to travel and work again. If enough people got COVID-19, survived, and became immune, surely that’d stop the virus in its tracks, right? It's a bit more complicated than that, researchers tell Bustle.

“Herd immunity can occur when enough people become immune to a disease to make its spread unlikely,” Dr. Teresa Bartlett, M.D., senior medical officer at Sedgwick, a claims management service, tells Bustle. It’s why vaccinations work; if someone can’t get vaccinated for an illness — because they're allergic, or too young for it — the fact that everybody around them is immune can protect them from becoming infected with it.

People become immune to diseases in two ways: either by vaccinations or by catching the virus in question. Both methods encourage your immune system to produce antibodies that can recognize and kill the virus if you're exposed to it again. But there's still so much researchers are learning about how immunity to coronavirus works, which means myths about herd immunity are getting more airtime than they should.

Here’s why herd immunity is a long way off, no matter what somebody tells you on Facebook.

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Myth 1: "You Get Herd Immunity With Other Diseases, So It'll Work The Same For Coronavirus"

Unfortunately, coronavirus isn't like other illnesses. “The classic picture of herd immunity is best illustrated by diseases like measles or rubella,” Dr. John Sellick, D.O., professor in the department of medicine at the University of Buffalo’s Jacobs School of Medicine and Biomedical Sciences, tells Bustle. When people get measles or rubella, either through natural infection or a vaccine, their bodies produce antibodies that give them long-term, reliable protection against catching it again.

We usually don't see outbreaks of these illnesses, he says, because so many people have antibodies against them, mostly because of immunizations. The few people who don’t have those antibodies can’t catch the illnesses anywhere, because there's no local transmission thanks to the vaccine. (This is why when people stopped getting the measles vaccine, cases in the U.S. skyrocketed.)

“The situation is much more complicated with respiratory viruses like COVID-19,” he says. These kinds of viruses tend not to create herd immunity because they don't create the same strong, long-lasting immune responses as measles, rubella, or other diseases. Instead, our bodies often produce lower levels of antibodies that might not stick around for very long.

The difference between measles and the coronavirus is like carrying a strong umbrella in the rain versus carrying a lacy parasol: The antibodies you get from coronavirus simply don't offer the same level of protection as in other diseases.

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Myth 2: "If I Get It, It's Like Naturally Getting Vaccinated, So It's Not A Big Deal"

Some people think it's better to "just get COVID over with" in the hope that they'll have no symptoms, get antibodies, and be protected in the future. But getting the virus organically is very different from getting vaccinated against it.

"Individuals should NOT try to deliberately contract the virus," Dr. Jan Schwarz-Miller, M.D., chief medical officer at Atlantic Health System, tells Bustle. "This type of activity will only help the virus spread."

To understand why attending a coronavirus party in order to get immunity is a terrible idea, Dr. Sellick points to the flu. “Even though we have a vaccine and a fairly large number of cases, every year in the U.S. we never see ‘herd immunity’ that eradicates the flu,” he says. Not everybody in the population has the same immune response to the flu, and influenza antibodies start to wane in the body after a few months. Researchers now know it's the same with coronavirus: Everybody reacts differently to it, and the antibodies it produces aren't iron-clad guarantees you can't get it again. (Getting coronavirus twice hasn't been shown to be an issue yet, but scientists aren't ruling it out.)

If everybody around you has had coronavirus, the chances are high that you'll get it yourself — but, just like the flu, it's really hard to predict exactly how your immune system will react to it. You could get really, really sick, or be asymptomatic and risk other people's lives.

COVID-19 also has a higher mortality rate than chicken pox or measles, Dr. Christian Rojas Moreno, M.D., of the University of Missouri tells Bustle. "Infected people not only have risk of complications and death but they are also putting their families and friends at risk." Vaccines are different, he says. "They create immunity without causing the illness and its complications." It's just not worth gaming the system.

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Myth 3: "Herd Immunity Is Just Around The Corner"

"To reach herd immunity for COVID-19, it is estimated that at least 70% of the population would need to be immune," Dr. Rojas Moreno tells Bustle. In the U.S., that's around 200 million people, and as widespread as coronavirus has been, we're a long way off from that. "Based on CDC serosurvey data, national rates overall in May were about 6% of the population," he says. It's also worth noting that if 200 million people got the virus, it's possible that an estimated 7 million would die, based on Johns Hopkin University's analysis. So waiting for herd immunity to occur naturally would be courting disaster.

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Myth 4: "Coronavirus Antibodies Mean You’re Protected For Life”

This is one myth that requires closer inspection. A crucial part of herd immunity is the idea that once you’ve had the illness, you shouldn’t be able to catch it again or pass it on to anybody else. Unfortunately, coronavirus might not work like that.

“We don't yet fully understand how the immune system responds to the SARS-CoV-2 virus,” Dr. Gwen Murphy, M.D., an epidemiologist with testing company LetsGetChecked, tells Bustle. “Many people who become infected with the coronavirus develop antibodies as part of the body's response, to try and clear the infection.” But immune responses to COVID-19 have turned out to be really variable. Some people produce a lot of antibodies, while others don’t produce any at all.

Studies are also showing that people who’ve had the coronavirus once, especially if they were asymptomatic, might only be protected by their antibodies for a few weeks or months. “With SARS-CoV-2, evidence is emerging that the antibody response begins to wane in a matter of months,” Dr. Sellick says. Dr. Bartlett says that research shows antibodies are stronger in people who’ve had coronavirus badly, so if you had a mild case, chances are you might not have any immunity at all after a short time.

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Myth 5: “You Can Calculate If Your Area Has Herd Immunity"

If you live somewhere with a high local transmission rate, or that's already gone through a surge, you might think there's some immunity floating around.

“People try to ‘calculate’ herd immunity,” Dr. Sellick says. “This works on paper but not in real life.” If you live somewhere that had a high R number — the average number of people each person with coronavirus will go on to infect — and has now dropped to a much lower one, you might assume that people are becoming immune, and it's fine to go out without a mask. But the R number, which is just an average, can change quickly, so it’s hard to determine what your local infection levels might be (not to mention the fact that people can and do travel from place to place, bringing infections with them).

“You can imagine that if you are living in a large apartment building in Manhattan or London, the opportunity to infect other people will be much greater than if you live in a rural area,” Dr. Sellick says.

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Myth 6: "A Vaccine Will Make Herd Immunity A Reality Right Away"

Unfortunately, this might not be quite right either. "It take quite a bit of time before we are able to produce and share the vaccine globally," Dr. Schwartz-Miller says. "Even once it’s available, vaccines are only useful if people take them." CDC data shows that less than 50% of all Americans get the flu vaccine every year, she says, and the number of people who get the COVID vaccine will have to be a lot higher to create herd immunity – between 70 and 90%.

One vaccine also might not be enough. “This will not be a matter of vaccinating everyone and COVID-19 will go away,” Dr. Sellick says. “I suspect that this will wind up being something akin to influenza where we have to give a vaccine on a regular basis.” Like the flu, which requires a new vaccine every year, the coronavirus could mutate and make old vaccines obsolete.

This means that even if a coronavirus vaccine comes out next year that's 100% effective, and everybody takes it, we still won't have complete herd immunity. The virus might evolve, and the vaccine would need to be updated to match it.

Collective immunity probably isn't going to help us live coronavirus-free, unfortunately. But yearly coronavirus vaccines still sound better than more quarantine, IMHO.

Experts:

Dr. Teresa Bartlett M.D.

Dr. Gwen Murphy, M.D.

Dr. Christian Rojas Moreno, M.D.

Dr. Jan Schwartz-Miller, M.D.

Dr. John Sellick, D.O.

Studies cited:

Kreijtz, J. H., Fouchier, R. A., & Rimmelzwaan, G. F. (2011). Immune responses to influenza virus infection. Virus research, 162(1-2), 19–30. https://doi.org/10.1016/j.virusres.2011.09.022

Fine, P., Eames, K., Heymann, D.L. (2011) “Herd Immunity”: A Rough Guide, Clinical Infectious Diseases, Volume 52, Issue 7. Pages 911–916, https://doi.org/10.1093/cid/cir007

Robbiani, D.F., Gaebler, C., Muecksch, F. et al. (2020) Convergent antibody responses to SARS-CoV-2 in convalescent individuals. Nature (2020). https://doi.org/10.1038/s41586-020-2456-9