Can you catch coronavirus twice? Short answer: It's unlikely

There were early reports of people appearing to have multiple coronavirus infections in a short space of time. But the scientific consensus is that testing was the issue, with patients being incorrectly told they were free of the virus.

Sporadic reports of Covid-19 patients seemingly becoming reinfected with the coronavirus have sparked doubts about whether people can ever gain immunity against the pathogen — and although current research suggests reinfection within a short time frame is unlikely, some researchers are hesitant to completely dismiss the idea.

Coronavirus immunity

Elitza Theel, director of the infectious diseases serology laboratory at the Mayo Clinic, said researchers are finding that coronavirus "antibodies will peak at about 20 to 30 days after symptom onset, and then they decline," and "they seem to decline much more rapidly in individuals that were asymptomatic or had mild forms of the disease."

Given that antibodies help to neutralize the coronavirus and are believed to provide people with immunity against the pathogen, those findings have raised alarms among some observers that people may gain natural immunity to the coronavirus for only a few months.

Robert Glatter, an assistant professor of emergency medicine at Lenox Hill Hospital and Northwell Health, explained that, if people could become reinfected with the coronavirus within a short period of time, it would mean that people may need to receive multiple vaccinations against the virus throughout the year to control the coronavirus' spread.

"It would definitely be a predicament for public health, there's no question about that," especially if there isn't a vaccine against the virus, said Kamran Kadkhoda, medical director of immunopathology at the Cleveland Clinic. "In the absence of a vaccine, the main thing that we'd have against reinfection are these prevention measures" such as physical distancing and face masks, Kadkhoda explained.

Research suggests reinfection is unlikely

But despite the anecdotal reports from doctors about patients becoming reinfected with the coronavirus, researchers say there's no evidence supporting the notion that people can become reinfected with the virus within a short time period.

"I haven't heard of a case where it's been truly unambiguously demonstrated," said Marc Lipsitch, an epidemiologist at the Harvard TH Chan School of Public Health.

For instance, South Korea's Center for Disease Control and Prevention in one study confirmed that, among 285 cases of people who again tested positive for the coronavirus two months after receiving their initial positive test results (including some who were experiencing Covid-19 symptoms two months after their initial diagnoses), none of the patients' new samples contained enough virus particles to allow researchers to grow the virus from the samples in a lab. 

Researchers said those results indicated that the patients weren't actively infected with the virus, and the diagnostic tests likely had detected dead virus particles that remained in their bodies or generated false-positive positive results.

Further, the researchers noted that none of the patients who re-tested positive for the coronavirus transmitted the pathogen to others.

Why people experiencing Covid-19 symptoms twice?

Clinicians say more research is needed to answer the question of why some patients appear to fall ill with Covid-19 more than once, but some believe that such patients simply relapse because the coronavirus lays dormant in their bodies and reemerges—an occurrence that's been seen with some viruses that often result in lifetime immunity, such as the chickenpox virus, according to Daniel Griffin, an infectious diseases doctor and researcher at Columbia University Medical Center.

It also may be possible that some patients experience a long course of infection that ramps up months after they first contract the coronavirus and initially experience symptoms of Covid-19, some experts have said. And others have speculated that some patients may contract a different virus with similar symptoms to Covid-19 and assume they've been reinfected with the coronavirus. 

But 'no one wants to dismiss the possibility' of reinfection completely.

However, while most experts say they don't think it's likely people can contract the coronavirus more than once within a short period of time, "no one wants to dismiss the possibility" of reinfection altogether, Monica Gandhi, a professor of medicine and associate chief of infectious diseases at the University of California-San Francisco, said.

And Griffin noted that, if researchers eventually find two different versions of the novel coronavirus' genetic code in one patient's body, it could point to two separate infections.