Repeated infections with the coronavirus can be dangerous, study shows

“Getting it a second time is almost like trying your hand at Russian roulette again,” said Al-Aly, who is also a clinical epidemiologist at the University of Washington. “You may have dodged the bullet the first time, but every time you get an infection you try your luck again.”

The paper, published on Thursday in the journal Natural medicine, includes an analysis of electronic medical records in the VA National Health Care Database. It was found that patients with repeated infections had more complications in different organ systems during the initial illness and for a longer period and were more likely to be diagnosed with long covid than people who did not get another infection. The findings applied regardless of people’s vaccination status or whether they had been groomed.

The study included a review of the medical records of 5.8 million patients, of whom 443,588 were infected once and 40,947 who were infected twice or more. The median time between the first and second infection was 191 days. Compared to people who experienced only one infection, those who were reinfected had twice the risk of death, three times the risk of hospitalization, twice the risk of long-term covid, three times the risk of heart problems and blood clotting disorders, and twice greater risk of fatigue.

But the research is only a small part of the story of re-infection and SARS-CoV-2.

When the pandemic started, everyone’s immune system started in a similar place as if they had never encountered the virus. Almost three years later, some people have been infected and re-infected with different variants and vaccinated and boosted with different products creating great diversity in our immune systems around the world — meaning there are no simple answers to how a previous infection will affect someone’s response to re-infection. It is estimated that more than 80 percent of Americans have been infected with the coronavirus at least once.

Monica Gandhi, an infectious disease specialist at the University of California, San Francisco, said it’s important to remember that studies using electronic medical records “cannot reliably predict causation.”

Gandhi pointed to other studies, including one that looked at 26 studies re-infections that show they become less serious over time. Another study from Catarrh examined patients with different vaccination histories in more comprehensive ways and found that reinfections usually did not progress to severe, critical, or fatal outcomes. These studies have not yet been peer-reviewed.

Gandhi also said there is research showing that infection, re-infection, vaccination and boosting expand and diversify components of the immune system that may make people “better able to respond to the latest sub-variants as we continue to live with Covid-19”.

William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center who was not involved in the study, said the findings are consistent with recent work on the long-term effects of the flu that shows the virus stimulates an immune response that can “simmer” after the first illness.

“All of these respiratory viruses seem to have long-term effects that we haven’t appreciated in the past,” Schaffner said.

Al-Aly said his research began as a way to answer questions from patients he visited at the VA in the spring of 2022 as the omicron variant jumped.

“They were infected before and vaccinated, and they talked as if they were invincible,” Al-Aly said. So he and his colleagues began to question whether reinfection was important.

“The short answer is: Absolutely. It absolutely is,” Al-Aly said.

As we head into winter when the flu, respiratory syncytial virus and coronavirus are circulating, Al-Aly suggested people consider what they can do to reduce their risk of infection.

“I’m not advocating isolation or any draconian measures, but I feel like if you’re getting on a plane, for example, to see your family for Thanksgiving, well, wear that mask because it’s going to protect you and those around you,” he said. He said.