Reinfections with COVID-19 May Be Frequent, But Not Harmless
Experts warn that BA.5, which currently accounts for the majority of cases in the U.S., may be particularly likely to cause reinfections, even among people who have had the virus relatively recently. Scientists have similar concerns about BA.2.75, another transmissible Omicron subvariant that is spreading quickly in some parts of the world, including India, but does not yet make up a significant percentage of new cases in the U.S.
How much should reinfections worry you? Here’s what we know so far.
You may not get as sick as you did the first time
If your body has had practice dealing with the SARS-CoV-2 virus, it should perform better the next time around, ideally keeping your second illness milder.
The body mounts an immune response after either having COVID-19 or getting vaccinated against it. These defenses significantly reduce your chances of experiencing severe disease or dying if you get infected again, says Dr. Jeffrey Cohen, chief of the laboratory of infectious diseases at the National Institute of Allergy and Infectious Diseases. (People who are immunocompromised may not mount a robust immune response, leaving them susceptible to serious outcomes even after a prior exposure or vaccination.)
But getting infected is not a guarantee that you won’t get sick again in the future, especially with BA.5 and other Omicron relatives circulating globally.
Triple-vaccinated, previously infected health care workers gained almost no immune benefits (as measured by antibodies, T cells, and other immune responses) after being reinfected by Omicron, according to a study published in the journal Science in June. In other words, their immunity didn’t exceed what they had already generated from vaccines and prior infections. People who’d been fully vaccinated but never infected did get a bit of a boost.
Another study, published in Nature in May, found that unvaccinated people gained little lasting protection after being infected by Omicron.
“Getting an Omicron infection is not a good way of boosting your immune response,” says Rosemary Boyton, co-author of the Science study and a professor of immunology and respiratory medicine at Imperial College London. Her study showed that infections during the first Omicron wave are “not necessarily protecting you against BA.4 and BA.5 and the subsequent strains. That may be why we’re seeing people getting frequent breakthrough infections and reinfections.”
Even mild disease carries risk
If reinfections are likely to be mild, is it such a big deal to get sick again? It can be. A study posted online in June as a preprint (meaning it had not yet been peer-reviewed) found that reinfection adds “non-trivial risks” of death, hospitalization, and post-COVID health conditions, on top of those accumulated from an initial SARS-CoV-2 infection. Organ failure, heart disease, neurologic conditions, diabetes, and more have been linked to SARS-CoV-2 infections.
Study co-author Dr. Ziyad Al-Aly, an assistant professor at the Washington University School of Medicine in St. Louis, says the paper has been misinterpreted a bit; some have incorrectly assumed it means second infections are worse than primary ones. What the paper actually shows, Al-Aly says, is that additional infections come with additional risks. They may be smaller than those of a first infection, but they can pile up over time. “If your risk was X,” after a first infection, after the second one “it’s X plus Y,” he explains.
Even if a reinfection doesn’t make you very sick right away, it could increase your chances of developing chronic post-COVID health issues, the paper suggests.
“Second infections are less likely [than first infections] to be severe,” Cohen says. “But there can be damage even from that second infection.”
You can get Long COVID after a reinfection
Long COVID is one of the most feared risks of infection, and it can happen even to fully vaccinated people who have mild cases of COVID-19. The latest federal data suggest about one in five adults who catch COVID-19 will develop Long COVID symptoms, which can include fatigue, cognitive dysfunction, chronic pain, and more.
Cohen says it’s not clear yet whether someone is more or less likely to develop Long COVID after a second infection compared to their first, but there have been documented cases of people developing long-haul symptoms after a reinfection. “It certainly is possible,” Cohen says, but there’s not yet enough data to say how common that outcome is.
“You’re almost rolling the dice again,” Al-Aly says. “You may have been one of the lucky ones initially…but it doesn’t really mean that’s going to happen every time.”
Are reinfections inevitable?
Catching COVID-19 is always something to avoid as much as possible, using strategies like staying up-to-date on vaccinations, wearing a high-quality, well-fitting mask indoors, improving indoor ventilation, and asking everyone to take a rapid test before group gatherings.
But realistically, without comprehensive public-health strategies in place, and with variants like BA.5 causing new waves of disease, avoiding COVID-19 in the Omicron era is difficult for an individual to do without “living in a bubble,” Al-Aly says.
Cohen says that reality underscores the importance of developing new tools, such as multi-strain vaccines that could protect against both current and future variants. Some experts are also excited by the possibility of nasal vaccines, which could hopefully slow transmission by building immune reservoirs where the virus typically enters the body. Both products are currently in development, but not yet ready for public distribution.
Reducing the number of reinfections is necessary not only for individuals’ health but also for public health, Boyton says. Medically vulnerable and immunocompromised people won’t be safe as long as the virus is spreading widely, and everyone is at risk if it continues to mutate as it repeatedly infects large chunks of the population. “There is a danger that if you allow a virus to circulate in a vaccinated population at high transmission levels,” she says, “that it can then further mutate into something that is more pathogenic.”
In Boyton’s opinion, the benefits of reducing transmission are great enough to justify continuing public-health measures like masking on public transportation. Policymakers and individuals, she says, should be motivated to slow the virus’ spread as much as possible.
“It’s not a trivial illness to catch, even if you don’t get hospitalized or die,” she says.