Editor’s Note: Every Wednesday, James Hamblin takes questions from readers about health-related curiosities, concerns, and obsessions. Have one? Email him at email@example.com.
Dear Dr. Hamblin,
I was hospitalized with COVID-19 for two weeks in March. I was very lucky to avoid needing a ventilator, but the road to recovery has been long and confusing. I’ve struggled with residual pneumonia, alarming pains and sensations, anxiety and depressive feelings, a diminished sense of smell, what seem like hormonal changes, and continuing fatigue. I’m terrified of being reinfected, especially when I still feel weakened by the illness. How should I interpret the seemingly conflicting news about reinfection? Even if those of us who already had COVID-19 are unlikely to have a serious case the second time, can we still infect others if we get the virus again?
F. T. Kola
San Francisco, California
I’m not sure that telling people not to worry is ever productive. It tends to have the opposite effect. It’s like telling a person not to look at the horrifying thing happening right over their shoulder. So while I won’t tell you not to worry about this, hopefully I can give you cause not to.
I get why you’re concerned. If anxiety is born out of uncertainty, it doesn’t pair well with thinking about the immune system. The biggest lingering questions about this virus all have to do with immunity. We can’t chart a course back to anything resembling normal life until we know how reliably immunity is developed by infected people, and how long it lasts. If people have even a small chance of getting sick twice within a matter of months, it could mean that many may not feel comfortable going back to the life they once lived until a vaccine is in widespread use.
Generally with respiratory viruses, people who have gotten sick can expect to be infected again at some point, and get sick as a result. Protective antibodies naturally wane over time. Viruses also change over time, especially RNA viruses like this one. This happens every year with influenza, such that immunity from one year’s strain may not protect someone from the next year’s strain.
A flood of headlines over the past few weeks stoked many of our worst fears, warning about instances of people getting infected twice. But despite the way much of the coverage has been framed, so far what we’ve learned about reinfection has been largely reassuring. Globally, more than 25 million people have tested positive for the coronavirus, and we know of very few people who have gotten infected twice. In those that have, the immune system seems to be functioning as we would hope: Antibodies and other protective immune mechanisms are apparently identifying the virus and clearing it before it causes serious illness.
The spate of confirmed reinfections that caused you and so many others concern when they were reported in late August—one in Hong Kong, four in the Netherlands, and one in Belgium—all involved mild or no symptoms. Combine them with evidence about the ubiquity of protective antibodies developing in people after they’ve had COVID-19, and the rarity of cases of reinfection suggests a meaningful degree of protection from a second bout of illness for at least a few months. Making longer-term estimates is difficult, because the pandemic hasn’t been around longer.
Many news reports were scarier than they needed to be, because they implied that people had been sick and then gotten sick again. The cases were occasionally referred to, inaccurately, as proof that you can “catch COVID twice.” But testing positive for the coronavirus doesn’t mean you have COVID-19. Though the terms are often used interchangeably, the difference between getting infected by the virus twice and getting a severe disease twice is massively consequential.
No matter how robust your immune system’s memory is, it won’t stop the virus from temporarily landing on your hands or in your nose, and being detected during a swab test. But in such instances, antibodies should eradicate the virus before it replicates so widely as to make you highly contagious, and before it makes you sick. We’re really interested in two specific questions: Are people carrying the virus getting sick again? And are they contagious?
Evidence is only beginning to trickle in. The first widely reported case of someone apparently getting sick twice was published last week. Researchers at a public-health department in Nevada reported in a preprint research article that a 24-year-old had developed vague symptoms (headache, diarrhea, nausea) beginning in March. At the time, he tested positive for coronavirus. He subsequently tested negative. Then, in June, he developed severe respiratory symptoms and tested positive again. The report suggests that both illnesses were COVID-19.
What happened here has many possible explanations. The report said the virus that caused the first infection was genetically distinct from the second, based on minor mutations, but not so dramatically different that the virus would be considered a new strain that the body shouldn’t recognize. So it’s plausible that the man did not develop antibodies after his first infection (he wasn’t tested for them), or that they waned, or that they were present but simply not entirely effective. Another possibility is that his March symptoms were due to another virus, and his coronavirus infection was actually asymptomatic.
As long as testing and tracing protocols remain incomplete, we should expect more curious reports like this one. But the current evidence around reinfection is not reason for people who have gone through clear cases of serious COVID-19 to worry that they are in for another bout of brutal disease. No one has been documented as having had a serious case twice.
On the whole, the picture that’s developing is one in which our immune system seems to be developing a memory of the virus as we would expect—and, if anything, our protective mechanisms are overreacting. In the process of trying to eradicate the virus, our immune systems can go into overdrive and harm or even kill us. Even now, months after your infection has been cleared, a prolonged immune response may explain some of the symptoms you’re still dealing with.
Unfortunately, in keeping with immune responses to other respiratory viruses, coronavirus antibodies are unlikely to last more than a couple of years. If an effective vaccine takes years to reach everyone, you potentially could get sick again. The same could happen if the virus mutates substantially, even if you do have effective antibodies. So everyone has a stake in ensuring that a vaccine is carefully developed, justly distributed, and widely used. Even if you’ve been sick—and everyone you love and care about has been sick—you will eventually need to recruit a new round of antibodies.
While there’s no reason to panic or assume that a second harrowing experience is in your near future, there’s also no reason yet to behave as though you’re not at risk of getting sick again or, more likely, carrying enough of the virus to infect others. Even if you have antibodies and we can assume you’re mostly or entirely protected, we lack the certainty to suggest that universal public-health guidance doesn’t apply to you. The worst is very likely behind you, but best to act as though it’s not.
“Paging Dr. Hamblin” is for informational purposes only, does not constitute medical advice, and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. By submitting a letter, you are agreeing to let The Atlantic use it—in part or in full—and we may edit it for length and/or clarity.