According to a study published earlier in this month in Nature Medicine, patients who had Covid-19 reinfections had a higher risk of health complications than those who had only been infected once, leading some people to believe that reinfections are more dangerous than initial ones. However, health experts have pushed back on this idea, saying the study's data has been misinterpreted.

The risks associated with Covid-19 reinfections

For the study, researchers analyzed data from over 5 million patients in the U.S. Department of Veterans Affairs' (VA) electronic health care database.

The researchers found that 443,588 patients had experienced one Covid-19 infection, and 40,947 patients were infected at least twice. Of those in the second group, 37,997 (92.8%) patients had two infections, 2,572 (6.3%) patients had three infections, and 378 (0.9%) had four or more infections.

Compared with individuals who were only infected once, participants who were reinfected experienced a two-fold increase in the risk of death, long Covid, and fatigue, and a three-fold increase in the risk of hospitalization, heart problems, and blood clotting.

The researchers also found an increased risk of complications across all patients, regardless of vaccination status. The risks of complications, including pulmonary, cardiovascular, hematological, diabetes, gastrointestinal, kidney, mental health, musculoskeletal, and neurological disorders, were most prevalent during an active infection—but they lingered six months after infection.

According to Ziyad Al-Aly, study author and chief of research and development at the VA St. Louis Health Care System, the research shows that reinfections can result in health complications just like an initial infection.

"Getting it a second time is almost like you're trying your chance again with Russian roulette," Al-Aly said. "You may have dodged a bullet the first time, but each time you get the infection you are trying your luck again."

Are repeat Covid-19 infections more dangerous?

After the study was published, some news outlets, as well as discussions online, suggested the findings showed that Covid-19 reinfections were riskier or more dangerous than initial infections.

However, Jeremy Faust, an emergency medicine physician at Brigham and Women's Hospital and editor-in-chief of MedPage Today, argued that this was not the case and that the findings have been misinterpreted by the media.

In fact, the study's authors themselves wrote that their "analyses should not be interpreted as an assessment of severity of a second infection versus that of a first infection, nor should they be interpreted as an examination of the risks of adverse health outcomes after a second infection compared to risks incurred after a first infection."

According to Faust, the study's findings actually show that "[g]etting repeat infections is not benign," particularly for patients who are sick enough to seek medical care for a reinfection.

Instead of all reinfected patients having a higher risk of health complications, the study found that "[f]or a subset of patients sick enough to seek medical attention upon reinfection, more bad things happened compared to patients who either did not have reinfections, or who did but did not need to seek medical attention," Faust writes.

In addition, other health experts have noted that the VA population included in the study does not accurately reflect the general population. According to John Moore, a professor of microbiology and immunology at Weill Cornell Medical College, VA patients are older, sicker, and men, who are more likely to have health complications.

Other research also suggests that reinfections tend to get less severe over time, and that infection, reinfection, vaccination, and boosting increase and diversify the parts of the immune system that can help people become "better able to respond to the newest subvariants as we continue to live with covid-19," said Monica Gandhi, an infectious diseases specialist at the University of California-San Francisco.

Overall, because reinfections can also come with health complications, health experts recommend people take precautions to reduce the risk of infection ahead of the holiday season. "I'm not advocating for lockdown or any draconian measures, but I feel if you are boarding a plane, for example, to see your family for Thanksgiving, well, wear that mask as it will protect you and those around you," Al-Aly said. (Faust, MedPage Today, 11/29; Lapid, Reuters, 11/10; CIDRAP News, 11/11)