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You got sick with COVID back in January, so you figured you were done with the virus for a while. But then you began feeling a scratchy throat and a runny nose, took a home test just in case — and that second line blazed red once again.

You might well be wondering: How this can happen? Is it possible to get COVID again just a few months or even weeks after recovering from a case?

We asked four specialists to answer frequently asked questions about reinfection.

I thought I was immune – at least for a while — after having COVID. Is that not the case?

If you caught a previous variant — before the arrival of omicron — that meant you had an 84% lower risk of infection, significantly lowering your risk of getting COVID again, especially in the months right after you were sick.

But the omicron variants changed that.

A study published in March found the risk of reinfection "increased substantially" with the emergence of omicron in November, says Juliet Pulliam, lead author of the study and director of the South African Centre for Epidemiological Modelling and Analysis.

There are several omicron variants now circulating around the world, and they are very transmissible and very good at overcoming immunity, whether it's from vaccination, prior infection or both.

These omicron variants don't just evade protection you might have gained from a non-omicron version of SARS-CoV-2; you can catch the newer variants of omicron even if you had the original omicron variant before.

And any protection from infection wanes over time, so if it's been a few months since your last COVID shot or since you recovered from a case, you're more likely to be susceptible to reinfection.

But there's some slightly good news: For now, the newest omicron variants don't seem better at overcoming immunity than the original omicron.

The most recent resurgence in South Africa is now being driven by omicron sub-lineages BA.4 and BA.5. With these variants, "the risk of reinfection seems to be about the same as it was for BA.1 — so higher than for previous [non-omicron] variants but not any higher than the initially circulating omicron sub-lineage," Pulliam tells NPR in an email.

How soon could I get reinfected?

That's something experts are still trying to figure out. But 60% of reinfections from non-omicron variants between March 2020 and March 2021 in Denmark occurred less than two months after the first infection, researchers found in a preprint study, which has not been peer-reviewed or published.

That means you may have a shorter time of maximum protection than you thought after an infection.

Keep in mind: The Danish researchers only looked at 15 confirmed reinfections among 593 suspected cases. The number is low for a few reasons: for one thing, reinfections weren't as common then.

Because the newer variants are much better at overcoming prior immunity, our specialists say that if you recovered from a case of COVID fairly recently and then begin showing COVID-like symptoms, you should get tested to see if you have it again.

Is a reinfection more likely to be mild or could it be severe?

Research from South Africa suggests that prior infection does protect against severe outcomes, including hospitalization and death.

With reinfection, hospitalization and death "does seem to happen occasionally but both natural infection and vaccination seem to provide good protection against severe outcomes in most individuals," Pulliam says.

Another study from Qatar found that previous infection was about 87% protective against severe or fatal COVID-19.

But keep in mind that certain conditions — such as having had an organ transplant, ongoing cancer treatments or heart or lung disease — make you more vulnerable to bad outcomes, even if you've encountered the virus before through vaccination or infection.

"In immunocompromised patients," the intensity of illness "depends on the patient and it depends on how impaired their immune system is," says Jacob Lemieux, an infectious disease doctor at Massachusetts General Hospital. "We can't precisely say what the effect would be."

But the intensity of your illness also depends on how long it's been since your last vaccination or previous bout with COVID, since such protection wanes over time — so staying current on your vaccine schedule is a good idea.

I took Paxlovid, and a few days later I tested positive again. Is this a reinfection?

According to Robert Wachter, a professor and chair of the department of medicine at University of California, San Francisco, this is probably not an example of reinfection but something different, known as "rebound," when some patients begin experiencing symptoms and test positive again 2 to 8 days after taking the medication.

That's what happened to Wachter's wife. After taking Paxlovid, her symptoms improved markedly and she started testing negative on rapid tests. But four days later, she developed new symptoms – for the first round, she had a sore throat, fatigue, and a headache, and when it came back, it felt like a really bad cold with congestion – and she tested positive again.

The potential for rebound made him rethink the use of Paxlovid among younger people who aren't as at risk of severe outcomes, he says. But if he were to get sick, because of his own potential risk factors, he'd still take Paxlovid.

That's because in the clinical trials, Paxlovid lowered the rate of hospitalization by 89% among high-risk people, so those who have factors putting them at risk, like being immunosuppressed or over the age of 65, see a major benefit from taking the antiviral. That protection is true for both vaccinated and unvaccinated people who are at high risk, according to a new study.

"That's real," Wachter says. "How meaningful that is for you really depends utterly on your rate of hospitalization and how much risk you have for a bad case that would make you very sick and potentially put you in the hospital or potentially kill you."

Do vaccines help prevent reinfection?

Getting vaccinated can help prevent infection and reinfection, so it's a good idea to get the shots even if you've had COVID before and thought you were protected.

"For those who are vaccinated and those who have been infected, they are much better protected," says Peter Palese, a professor and chair of the department of microbiology at the Icahn School of Medicine at Mount Sinai.

Especially if you had a serious case before, getting up-to-date on your COVID shots now means you will likely have a less-severe case if you're reinfected, Palese says.

"Vaccination vaccination vaccination. Because yes, it will not protect you against the emergence of mild disease, but they will protect you from having a ventilator, being the ICU" or dying, he says.

But the immunity offered by vaccines, especially against infection, begins to wane after a few months, so getting a booster (or a second booster if you're eligible) is a very good idea.

If you were hospitalized before with COVID and then received two mRNA vaccines, that blend of protection was 35% effective in preventing subsequent hospitalizations during the first omicron wave. If you got a booster, that number rose to 68% effective against hospitalization.

And no vaccine is perfect, so continuing to take precautions – wearing a mask, getting tested if you have symptoms or are exposed to COVID, improving ventilation, and more – is still recommended, especially during surges like the one the U.S. is currently seeing.

Can getting COVID multiple times have long-term effects?

Long-term damage from repeat reinfections, like organ damage, is "the big question, and I haven't seen any data yet that can address it," Pulliam says.

And experts believe each COVID case could lead to long COVID, even if you were fine last time.

One in five adults experience continuing health issues after acute cases of COVID, including "persistent symptoms or organ dysfunction," according to a study published by the U.S. Centers for Disease Control and Prevention.

"There does seem to be a risk of long COVID or symptoms after resolution of the acute infection in a subset of people, and we don't really know how common that is yet or how long it lasts," says Lemieux.

How am I supposed to cope with the emerging – and changing – information about reinfection risks?

"It's a really frustrating situation, because I think everyone wants to be done with this virus, but we're just not. And we live in an era where we just want complete information at our fingertips, but we don't have it," Lemieux says.

That means we need to stay alert to the ways each new variant is changing, and how we respond to it – especially in the age of reinfection.

The same precautions used to prevent infection – masks, distancing, vaccinations, and more – work just as well for avoiding reinfection.

Another other point to keep in mind is that reinfections aren't that unusual for coronaviruses. "I don't think it's surprising the reinfection happens, because that's a feature of coronavirus biology," says Lemieux. "It's actually surprising, if anything, that it didn't happen more often with the initial variants."

Melody Schreiber (@m_scribe) is a journalist and the editor of What We Didn't Expect: Personal Stories About Premature Birth.

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