Why contracting COVID-19 is repeatedly risky for your health

AAt this point in the pandemic, it’s easy to think of COVID-19 as something more akin to the flu than a dangerous disease. But even though Omicron’s latest variants cause less severe symptoms than the original strain of SARS-CoV-2, COVID-19 is still far from a typical disease — especially if you get it more than once.

In a study published in Natural medicine, researchers report that re-infection with COVID-19 can affect some important organ systems. This risk applies to both short-term and long-term health effects, said Dr. Ziyad Al-Ali, a clinical epidemiologist at Washington University School of Medicine in St. Louis and senior author of the study.

He and his team analyzed 5.3 million health records from the US Department of Veterans Affairs, including people who did not test positive for SARS-CoV-2 from March 2020 to April 2022, and compared their health status with 443,000 people who tested positive once during that time period—then to another 41,000 who tested positive two or more times. (Most in the latter group had two or three infections, although a minority had four.) They examined adverse outcomes, such as hospitalizations and deaths, in the health records for these groups over six months.

People who had more than one infection with COVID-19 were three times more likely to be hospitalized and twice as likely to die than those who had only one infection. Those with multiple infections are also more vulnerable to other dangerous conditions; they were 3.5 times more likely to develop lung problems, 3 times more likely to have heart disease and 1.6 times more likely to have brain changes requiring care than people who had only once COVID-19.

The findings support other studies that have also documented the effects that COVID-19 can have on the body. More recently, in several presentations at the Society for Neuroscience Annual Meeting in November, scientists reported that the inflammation caused by COVID-19 can have lasting effects on the brain, including in children; 14 children aged 10-13 years who recovered from COVID-19 infections showed changes in sensorimotor regions of the brain on MRI up to 15 months after infection, compared to 35 children who were not infected. In another study presented at the same conference, adults who had even mild symptoms of COVID-19 also demonstrated brain changes four months after infection.

Read more: The latest variants of COVID-19 can evade vaccine protection, according to new data

Studies show that being infected more than once — an increasingly common scenario as the pandemic drags on and variants become more transmissible — can have a compounding effect. “We wanted to know if you get multiple infections, do they matter? Are these infections subsequent, or has the immune system adapted because it has seen the infection before and developed a way to deal with it?” says Al-Ali. “We found that if people are infected a second or third time, those infections certainly contribute to additional health risk, even if they are vaccinated.”

With each infection, the body’s resistance decreases a little more until, with enough attacks, it reaches the danger zone. “Cumulatively, each infection can push you closer and closer to the edge,” says Al-Ali. “That’s why avoiding a second or third infection is important to continue to stay healthy.”

Repeated infections can also increase the risk of Long COVID. It is not yet clear what puts people at risk of developing symptoms that can persist long after active infection is gone, and any encounter with SARS-CoV-2 could trigger whatever process leads to Long COVID. Repeated infections only increase the chances. “People will say, ‘I got COVID last Christmas and I didn’t get Long COVID.’ That’s wonderful, and that person is very lucky,” Al-Ali says. “But just because you dodged the Long COVID bullet once doesn’t mean you’ll dodge the bullet every time. Every time you get infected, you try your luck again.”

A deluge of re-infections of COVID-19 could pose a problem for healthcare providers this winter, when rates of other respiratory illnesses, such as influenza and RSV, may also rise. Health systems across the country already report high numbers of urgent care and emergency room visits due to respiratory illnesses, and Al-Ali’s findings suggest that people who have experienced multiple infections with COVID-19 may increase that burden.

The best way to avoid re-infection is to take familiar precautions: get vaccinated and boosted, wear masks when indoors and avoid gatherings if you feel sick. “We are not calling for a blockade or draconian measures,” Al-Ali says. “We want people to be aware of the risk and take precautions to reduce their individual risk of infection.” The health consequences of second and third infections are not zero, as some people think they are.”

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