Infection with COVID-19 brings with it the possibility of a high fever, dry hacking cough, and losing taste and smell. But, even months down the road, it carries the risk of developing long-COVID after infection, or getting sick with the virus all over again. The elusive virus is really good at evading the immune system, so it’s possible to be infected with COVID-19 multiple times per year, sometimes within only 90 days.
Those re-infections are proving to be risky, according to the results of a new study published today in the journal Nature Biology. The research from a team at Washington University School of Medicine in St. Louis and the Veterans Affairs St. Louis Health Care system found that repeat infections with the virus contributes to significant additional risk to multiple organ systems in the body.
Some of the risks include hospitalization, problems with the lungs, heart, and brain; problems with the musculoskeletal and gastrointestinal systems, and even death. COVID-19 reinfection also contributes to chronic illnesses like diabetes and kidney disease and issues with mental health, according to the new research.
“During the past few months, there’s been an air of invincibility among people who have had COVID-19 or their vaccinations and boosters, and especially among people who have had an infection and also received vaccines; some people started to referring to these individuals as having a sort of superimmunity to the virus,” said senior author Ziyad Al-Aly, a clinical epidemiologist at the Washington University in St. Louis, in a statement. “Without ambiguity, our research showed that getting an infection a second, third or fourth time contributes to additional health risks in the acute phase, meaning the first 30 days after infection, and in the months beyond, meaning the long COVID phase.”
The study found that people with COVID-19 reinfections were twice as likely to die in the time period studied and three times more likely to be hospitalized than those with who haven’t been reinfected with the virus.
People with repeat infections were also three and a half times more likely to develop lung problems, three times more likely to suffer heart conditions, and 1.6 times more likely to experience brain conditions than patients who had been infected with the virus once.
The study also indicated that the risk seems to increase with each infection with the virus, so it’s better to avoid more infections, according to Al-Aly.
Limiting exposure to the virus is especially important as the US heads into the winter months, with new variants emerging, mutating and already causing an upswing in infections in some parts of the country, Al-Aly said. “People should do their best to prevent repeat infections by masking, for example, getting all of their eligible boosters, staying home when sick. Also, get a flu shot to prevent illness. We really need to do our best to reduce the chance we will have a twin-demic of both COVID-19 and the flu this winter season.”
The researches studied close to 5.8 million anonymized health records from a databased maintained by the United States Department of Veterans Affairs (VA). The VA is the country’s largest integrated health-care system and the patients in the sample represented multiple sexes, races, and ages.
To compare, they created a controlled data set of 5.3 million people who didn’t test positive for COVID-19 infection from March 1, 2020, (when the pandemic began in the US) through April 6, 2022.
Using the same time frame, the researchers compiled a control group of more than 443,000 people who had tested positive for one COVID-19 infection, and another group of close to 41,000 people who had two or more documented infections. Those who reported multiple infections primarily had two or three infections, with a small number showing had four infections. No one in the study experienced five or more infections with COVID-19.
The team used statistical modeling to examine the health risks of repeat infections within the first 30 days after contracting the virus and up to six months after infection. The study accounted for COVID-19 variants such as delta, omicron, and BA.5 and the negative outcomes occurred among the unvaccinated as well as those who had received shots of the vaccine prior to reinfection.
“Our findings have broad public health implications as they tell us that strategies to prevent or reduce the risk of reinfection should be implemented,” Al-Aly said. “Going into the winter season, people should be aware of the risks and practice vigilance to reduce their risk of infection or reinfection with SARS-CoV-2.”