Can You Get Covid-19 Twice? What You Need to Know About Coronavirus Reinfection
Even if you have coronavirus antibodies, you may be vulnerable to reinfection for a number of reasons—so you could potentially get Covid-19 twice. Here's what that means in terms of symptoms, your antibodies, and vaccine production.
Can you catch coronavirus a second time?
One of the many fears surrounding Covid-19 is whether you can catch it again. The answer is yes, it appears so. A team of researchers at the University of Nevada, Reno, are examining the case of a patient who came down with Covid-19 twice, which would be the first identified reinfection in the United States. This news comes on the heels of the first documented case worldwide—a patient in Hong Kong, according to The New York Times.
The Nevada man, a resident of Washoe County, tested positive for SARS-CoV-2 (the virus that causes the Covid-19 infection) in April. He recovered and subsequently tested negative twice. Forty-eight days later in June, he tested positive again, and further analysis revealed that the virus DNA was different between his two infections. This suggests he was reinfected by a mutated strain of the virus.
Given the potential devastation caused by Covid-19—and the worry that there will be a second coronavirus wave—everyone from experts to people on the street hoped that a Covid-19 infection would trigger antibodies that would protect people, ideally for an extended amount of time. Now that seems less likely.
“This news doesn’t surprise me,” says Sandra Kesh, MD, deputy medical director at Westmed Medical Group in Purchase, New York. “Covid would have been the first virus in history to not mutate, and we knew at the outset that this wasn’t going to be the case,”
The tricky aspect of respiratory viruses like the novel coronavirus is that they tend to evolve quickly. Typically, your immune system protects you in a couple of ways: One, you develop antibodies to the invader. “Antibodies prevent the virus from infecting the cell,” explains Dr. Kesh. The second arm of your immune system is a T-cell response: T-cells kill off other cells that have been infected by a virus.
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How you might get reinfected
You could be susceptible to a second infection if your immunity wanes in the months after infection, or mutations in the virus allow it to evade detection by your immune system. If you had a mild Covid-19 infection, it’s possible your antibody response could be weaker, making you more susceptible, says Dr. Kesh. On the other hand, if there’s another strain of the novel coronavirus going around, the virus can evade those antibodies, and you can get sick again. (Learn if lockdown has hurt your immune system.)
Will a second Covid-19 infection be milder?
Often, being reinfected means you’ll have milder symptoms, says Dr. Kesh. That was the case with the man in Hong Kong—he was asymptomatic during his second infection, even though the virus was different from his first infection. (He was tested after traveling to Spain.)
That said: “If you get sick with a different strain, all bets are off,” explains Dr. Kesh. Scientists confirmed that the Reno man also contracted a different strain, and his Covid-19 symptoms the second time around were more severe. “Whether the mutations made the virus more virulent, no one knows,” she adds. Don’t miss what scientists are learning from Covid-19 long haulers.
Covid-19 reinfections seem to be rare
There have been over 26 million cases of Covid-19 globally, according to Johns Hopkins University of Medicine. Reinfection seems to be rare, but large population studies are needed, says Dr. Kesh. “I expect that once you get infected, you will have immunity. Whether that lasts months or a year is anybody’s guess still,” says Dr. Kesh.
There’s some good news there: A new study in The New England Journal of Medicine on nearly 1,800 patients in Iceland found that Covid-19 antibodies lasted at least four months. The authors say that more research needs to be done to determine if this will protect against reinfection.
What does this mean for vaccines?
Vaccines are designed to trigger the body to make protective antibodies, so when a person encounters the real germ, the body is already prepped and ready to eliminate it before they get sick. Will a Covid-19 vaccine even work if the virus can evade antibodies? The vaccines undergoing testing hope to target a part of the virus that the immune system will recognize even if the virus mutates, says Dr. Kesh.
“If SARS CoV-2 behaves the way other coronaviruses behave, it’s [likely relatively] stable, and a vaccine should be effective for a year, at least,” she says. It’s possible that this could be like a flu vaccine—scientists will need to tinker with it every year and make their best attempt at matching it up to the strains that are expected to be circulating that year.
What should you do if you think you have Covid-19 a second time?
The Centers for Disease Control and Prevention (CDC) says that if you develop Covid-19 symptoms again after a confirmed case, you should isolate yourself and discuss re-testing with your doctor.
The risk of reinfection is a strong reminder that everyone needs to continue to wear face masks and practice social distancing, says Dr. Kesh, even if you’re already been infected with the coronavirus.
- New York Times: First Documented Coronavirus Reinfection Reported in Hong Kong.
- University of Nevada, Reno: Nevada State Public Health Lab-led team studying Covid-19 reinfection.
- Sandra Kesh, MD, Deputy Medical Director at Westmed Medical Group in Purchase, NY.
- Johns Hopkins University of Medicine: Covid-19 Dashboard.
- The New England Journal of Medicine: "Humoral Immune Response to SARS-CoV-2 in Iceland."
- Centers for Disease Control and Prevention (CDC): When You Can be Around Others After You Had or Likely Had COVID-19.