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Can you get COVID twice? What we know about coronavirus reinfection

Recovering from the coronavirus gives you some immunity, but experts aren't sure how long it lasts.

Confirming COVID-19 reinfection is difficult because it requires genetic testing of test samples. Most labs are ill-equipped.  
Amanda Capritto/CNET
For the most up-to-date news and information about the coronavirus pandemic, visit the WHO and CDC websites.

Since the beginning of the coronavirus pandemic, experts have grappled with the question of how much immunity someone has once they've been sick with COVID-19 and whether that'll protect them in the future. While the coronavirus continues to mutate and work its way around the globe, more people have recovered from COVID-19 and may be wondering what kind of immunity that gives them to ward off a second infection, and whether they still need a vaccine. The answer to that second question is yes.

According to the US Centers for Disease Control and Prevention, every person eligible should get a COVID-19 vaccine, including those who've been sick with the coronavirus and recovered. This is because studies have shown that vaccination provides a strong boost in immunity to those who've recovered from COVID-19, and vaccination is a much safer way to get immunity from the coronavirus than getting infected with COVID-19. 

A CDC report released in August found that unvaccinated people who previously had COVID-19 were about 2.34 times more likely to get reinfected than vaccinated people who've had it. Another study published this month by scientists at the Yale School of Public Health and the University of North Carolina at Charlotte, which examined other coronaviruses related to the virus that causes COVID-19, found that immunity following COVID-19 infection might be short-lived. This may be especially true with contagious new variants such as delta and delta plus.

"As new variants arise, previous immune responses become less effective at combating the virus," said Alex Dornburg, who co-led the study, according to a Yale press release. "Those who were naturally infected early in the pandemic are increasingly likely to become reinfected in the near future."   

Matt Weissenbach, epidemiologist and senior director of clinical affairs for clinical surveillance and compliance at Wolters Kluwer, told CNET in August that you should think of a coronavirus vaccine as a "top-off" to your immune system's gas tank if you've already had COVID-19. 

"Certainly, any immunity is better than nothing," Weissenbach said. "But at this point there's no replacing the protective factor of vaccination."

How much natural immunity do you have after COVID-19, exactly? How likely are you to get it twice? Does it mean you can skip the second dose of the vaccine? For many questions surrounding the coronavirus, research is still underway. Here, we walk you through what experts know and, just as importantly, what they don't know about COVID-19 reinfection, including what to look out for and steps you can take to protect yourself and get tested.  

Patients get checked in for their doctors' appointment outside the facility and aren't permitted indoors until they get a text that the doctor is ready to see them. Free N95 masks were being given to those about to enter.

Sarah Tew/CNET

Is getting reinfected with COVID-19 something I should worry about?

As of August, Weissenbach said COVID-19 reinfection cases make up less than 1% of all COVID-19 cases. But tracking reinfection accurately is difficult because of decentralized testing, lack of communication between labs and a limited number of US labs that save COVID-19 testing samples, he said. In order to confirm reinfection, scientists need to compare the genetic material of previous and current tests.

Another factor that might lead to underreported reinfection cases is that many second instances of COVID-19 are mild, which leads people to not realize they're infected again, virologist Theodora Hatziioannou told Healthline

Recovering from COVID-19 can require bedrest.

Angela Lang/CNET

Does testing positive twice mean I've definitely been reinfected?

Not necessarily, especially if you're tested within three months of first getting sick, according to Weissenbach. If someone tests positive for COVID-19, tests negative and then tests positive again, it's likely due to viral shedding of the original virus, he said. 

"Many viruses can shed for quite some time after the illness has subsided," Weissenbach said. True reinfection with COVID-19 means that someone was infected with the virus on two different occasions, usually months apart. Long COVID-19, a syndrome that some people develop after having the coronavirus, is also not a reinfection or active infection. 

In the waiting room at the doctors' office, signs on every chair ask that patients refrain from sitting.

Sarah Tew/CNET

Why do I need the vaccine if I've already had COVID-19? Do I need both doses? 

According to a study from Kentucky that was analyzed in the CDC report on COVID-19 reinfection, people who previously had COVID-19 were about twice as likely to get it again if they weren't vaccinated, suggesting that the coronavirus vaccines are very effective even if you've already had the virus.

"If you have had COVID-19 before, please still get vaccinated," CDC Director Dr. Rochelle Walensky said in August. "Getting the vaccine is the best way to protect yourself and others around you, especially as the more contagious delta variant spreads around the country."

Weissenbach said that the strength of someone's natural immunity from infection likely won't last "over the long haul," and that vaccination might provide better protection. This is because vaccines target a "particular reaction" from your immune system, he said. 

"It's done so in a very targeted and emphasized way so that it generally is going to be a more robust, lasting immune response than may otherwise be provided naturally through your body," Weissenbach said. Think of it as a "double dose," he said.

But research shows people who've already had COVID-19 strongly benefit from a single dose of a COVID-19 vaccine, which is not the case for people who haven't been sick. According to an article in Nature, some people who've had COVID-19 and received just one vaccine shot mount immune responses equal to or greater than people who got both doses but never had COVID-19. 

To sum it up: Research shows that COVID-19 vaccines give you stronger immunity if you've already had the virus, but it probably isn't as imperative for you to get both doses, though the guidance still is for everyone to get both. 

Long COVID-19 and vaccines

Getting a coronavirus vaccine is helping some who are living with what's often called "long COVID" after being diagnosed with the coronavirus. Experts are still researching why, exactly, but getting a COVID-19 vaccine is helping relieve the symptoms of some long-haulers

In an earlier conversation with CNET about long COVID, Dr. Nasia Safdar, director of infection control at the University of Wisconsin, said, "Vaccination serves two purposes One, of course you want to get it before you have COVID so it protects you from it, but even in the people who have had the infection, anecdotally, it seems that vaccination helps with the symptoms of long COVID." 

If I'm sick, how long should I wait to get the vaccine? 

According to this Q&A with Dr. Jennifer Pisano, an infectious disease specialist with the University of Chicago Medicine who also had COVID-19 and is now vaccinated, you can get the vaccine anytime after you're no longer infectious or in quarantine.

People who received monoclonal antibodies or convalescent plasma as treatment for COVID-19, however, should wait 90 days before getting the vaccine, according to the CDC. It's recommended to wait if you've received monoclonal antibodies as treatment because they prevent your body from forming a robust immune response to the vaccine, according to a Cleveland Clinic report.

People with multisystem inflammatory syndrome should also consider delaying vaccination until they're no longer sick, the CDC says. 

It's hard to say whether COVID-19 symptoms such as dry cough and headache get worse or better with a second infection.

Sarah Tew/CNET

Is COVID-19 worse the first time or the second?

With most viruses, a second infection is usually milder than the first because the body has built antibodies against it. However, that's not always the case, and there's still much about SARS-CoV-2 doctors are continuing to reveal. With some viruses, already having antibodies for the virus can actually make a second infection worse. Dengue fever and Zika virus are examples. 

For most patients who've had COVID-19 more than once, symptoms have typically been mild or absent entirely with a second bout of the virus. But some patients' second illnesses have actually been worse than their first infection, making it difficult to claim either is the norm for the coronavirus.

How much natural immunity do I have from being sick?

Prior infection with COVID-19 reduces your chances of getting sick by about 80% after six months, according to a study published in The Lancet in March. For people over age 65, the protection is 47%. The same study points to research from the UK that found that natural immunity lasts at least six months after infection.

However, the amount of natural immunity someone has varies person to person, Weissenbach noted. "Every individual is different," he said. "If you're dealing with someone who has underlying health conditions or is immunocompromised, the concept of natural immunity can be quite a bit weaker." Factors like how much immunity a person's body mounted during the first infection, how much of the virus you were exposed to and the time between COVID-19 infections can all play a role.

In the University of Chicago Medicine Q&A, Pisano said that while it's possible for someone to have a higher antibody response to COVID-19 after getting sick than they would from getting the vaccine, there isn't enough data to compare how infection severity or antibody responses affect coronavirus immunity. 

"We don't have clear data on how antibody responses from a mild infection compared to a severe infection, or how protective those antibody responses are," Pisano said.

Is reinfection more likely with the delta variant?

The delta variant is much more transmissible than past variants and experts think it might be causing more severe disease. According to a CDC presentation, reinfection rates with the delta variant might be higher than reinfection with the previously dominant alpha variant. 

Weissenbach said that reinfection with viruses, including the coronavirus, is expected at some level. "Much like the flu virus mutates every year, we're seeing different mutations among the circulating variants of COVID-19," he said. So far, no variant (delta included) has found a way around our vaccines, as they all continue to protect against severe disease and death caused by the coronavirus.

But the ever-evolving virus will continue to mutate and form new variants so long as a significant portion of the population remains unvaccinated or without immunity. As it does, experts fear there could be a variant that strips away protection from the initial vaccines. 

Bottom line: "It's worth re-emphasizing that the vaccines are safe and effective at providing a protective immune response against the virus," Weissenbach said. "Inherently that benefit would minimize any risk of either initial infection or potential reinfection."

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.