Scientists have reported the first known case of COVID-19 reinfection in the U.S. this week, nearly two months after the initial case of reinfection was identified in China. The news was delivered via a paper in the Lancet on Monday, detailing how a 25-year-old in Nevada tested positive for COVID-19 in April and then again in June, after testing negative twice.
A resident of Washoe County, the man received a positive COVID-19 result at a community testing event in April, where he reported symptoms such as sore throat, cough, headache and diarrhea. While quarantining, he reportedly recovered from the virus and ultimately tested negative two separate times in May.
But 48 days after the initial infection, he was admitted to the hospital with severe symptoms, including fever, dizziness, headache, nausea, diarrhea and cough. On top of these symptoms, he reported shortness of breath, which “required ongoing oxygen support,” the researchers note, likely due to pneumonia. His case is believed to be the fifth documented instance of COVID-19 reinfection worldwide, one of which — that of an 89-year-old Dutch woman — has proven fatal.
The authors say the case study further proves that reinfection is a possibility. “Previous exposure to SARS-CoV-2 does not necessarily translate to guaranteed total immunity,” they conclude, adding that the “implications of reinfections could be relevant for vaccine development.”
Although the news may seem alarming, experts tell Yahoo Life that the information shouldn’t be cause for widespread panic. Here’s what you need to know.
With 37 million cases of COVID-19 worldwide, cases of reinfection are understandable
Dr. Angela Rasmussen, a virologist and associate research scientist at Columbia University, says the news isn’t necessarily unexpected. “I’m not surprised. Even when you have extremely rare, one-in-a-million events, you expect to see them in a large enough population,” Rasmussen tells Yahoo Life. “We don’t know how rare reinfection is, but it’s not shocking that we’re seeing it now that millions of people have been infected around the world.”
Even those who are reinfected may not experience more severe illness
Although the Nevada man experienced more severe symptoms the second time, the first person to have documented reinfection — a 33-year-old in Hong Kong — was asymptomatic the second time. Dr. Amesh Adalja, a senior scholar at Johns Hopkins Center for Health Security, says that the 25-year-old Nevada man’s reaction was likely the result of a unique immune response.
“You really have to think, what does the virus normally do? And these types of reinfections are extremely rare and not really something that I worry too much about,” Adalja tells Yahoo Life. “There's likely some kind of aberrancy in that person's immune system that allowed it ... to happen, so it's not anything that should change how we think about this.”
In a tweet thread on Tuesday, Rasmussen gave the same advice. “We don't learn much about horses by chasing unicorns, and the same is true for studying immune responses,” she tweeted. “Reinfection is interesting and should be studied, but until we have evidence that it is common, or that it's associated with increased disease severity, stay the course.”
It’s too soon to connect the cases of reinfection
While it may be tempting to try and draw conclusions about the individuals who have been reinfected, at this point, there isn’t enough evidence to do so. “The only similarity is that they were reinfected,” says Rasmussen. “It’s impossible to conclude a common underlying mechanism related to the immune response or the virus with just a handful of cases.”
Experts say it’s unlikely to be related to a mutation
Science is still studying the role that mutations in the virus may have played in the five cases of reinfection — including the latest, in Nevada — but at this point, Adalja doesn’t consider it to be a driving factor. “I don't think it's related to the mutations,” he says. “I think it's more likely related to idiosyncrasies in his immune system.”
The U.S. case of reinfection underscores the importance of safety measures
Although reinfection is unlikely, Rasmussen says individuals who have had the virus should operate as if they can get it again. “Especially since we don’t know how common reinfection is,” Rasmussen says. “We don’t know how long immune protection lasts, what the nature of that protection is, or risk of transmission by reinfected people, so people should exercise caution.”
Adalja echoes her thoughts. “The CDC does recommend that if you've had the virus within three months and you've gotten re-exposed, you don't have to self-quarantine — so there is likely some protection,” says Adalja. “But I think it’s still important for people to think about the fact that even though it's a low chance, it's a non-zero chance. We don’t have enough data to be able to completely have people change all their behaviors after they’ve recovered.”
For the latest coronavirus news and updates, follow along at https://news.yahoo.com/coronavirus. According to experts, people over 60 and those who are immunocompromised continue to be the most at risk. If you have questions, please reference the CDC’s and WHO’s resource guides.
Read more from Yahoo Life
Want lifestyle and wellness news delivered to your inbox? Sign up here for Yahoo Life’s newsletter.