Doctors and scientists who study Covid-19 agree that for most people, getting infected for a second — or third or fourth — time is basically inevitable. The longer the virus sticks around, the more common repeat infections have and will become, especially in light of the summer uptick and a new dominant variant.
There is no risk-free Covid infection. But researchers are trying to untangle just how damaging repeated infections might be — whether symptoms tend to become more or less severe from one bout to the next, and whether one’s risk of developing long Covid increases after multiple illnesses.
There is a dearth of data on Covid outcomes, including what proportion of people with repeat infections go on to develop longer-term complications, said Dr. Marc Sala, co-director of the Northwestern Medicine Comprehensive COVID-19 Center. But here’s what we know so far.
The severity of repeat infections
For many people who get Covid multiple times, subsequent infections will be as mild as or milder than their first, emerging data shows, likely because of partial immunity from previous infections, vaccination and the fact that the latest circulating variants generally cause less severe symptoms. There are a few exceptions — notably, among some people who are immunocompromised, older or had particularly severe previous infections. People who had a severe first infection are more likely to end up hospitalized or to require medical attention for a reinfection, said Emily Hadley, a research data scientist at RTI International who studies long Covid.
Reinfection and long Covid
The chances you will get long Covid from a reinfection are fairly unpredictable — several experts interviewed for this story used the metaphor of Russian roulette. The milder your symptoms, the less likely you are to get long Covid, said Dr. Peter Chin-Hong, an infectious disease specialist at the University of California, San Francisco. But every time you get infected, no matter the severity, there is always a chance that you can develop longer-term symptoms.
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- Long Covid: As more young Americans report serious cognitive problems, scientists suggest that the increase captures the effects of long Covid, most likely in addition to other effects of the pandemic, including psychological distress.
- Stroke Risk: The Covid vaccines made by Pfizer-BioNTech and Moderna may be linked to a slight increase in the risk of stroke when administered along with a high-dose flu vaccine that is usually given to older people, according to a new analysis by the F.D.A.
A buzzy paper that was published in Nature Medicine last fall showed that people with two or more Covid infections were more than three times as likely to develop lung and heart issues, and over 1.5 times as likely to have a neurological disorder, including brain fog and strokes, than those who were only infected once. The study used data collected from U.S. Department of Veterans Affairs health care centers, which meant the participants tended to be older than the general population, and overwhelmingly male. But it showed, in pretty stark terms, that multiple infections are worse than one, said one of its authors, Dr. Ziyad Al-Aly, the chief of research and development at the V.A. St. Louis Healthcare System.
Dr. Sala said he frequently sees patients who were more or less fine after their first couple of infections wind up with long Covid in the wake of a third or fourth infection.
“Just because you were lucky enough previously to not have more persistent symptoms, that’s not a reassurance you won’t the next time around,” he said.
Still, it’s not a foregone conclusion that reinfection definitively raises the risk of long Covid, said Fikadu Tafesse, a virologist at Oregon Health & Science University. “Reinfection is very contentious,” he said. “Literally depending on which paper you are reading, there’s contradicting information regarding that. So I don’t know what to believe.”