The risk of death, hospitalization and serious health problems from COVID-19 increases significantly with reinfection compared with a first round of the virus, regardless of vaccination status, according to a study published Thursday.
“Reinfection with COVID-19 increases the risk of both acute and long-term consequences of COVID,” said Dr. Ziyad Al-Aly from Washington University School of Medicine in St. Louis. “This was evident in unvaccinated, vaccinated and boosted people.”
The findings were drawn from US Department of Veterans Affairs data collected from March 1, 2020, to April 6, 2022, on 443,588 patients with a single SARS-CoV-2 infection, 40,947 with two or more infections, and 5.3 million uninfected individuals. Most subjects were male.
Reinfected patients had more than double the risk of death and more than three times the risk of hospitalization compared to those who contracted COVID only once. They also had an increased risk of lung, heart, blood, kidney, diabetes, mental health, bone and muscle, and neurological problems, according to a report published in Nature Medicine.
“Even if one had a previous infection and was vaccinated – meaning they had double the immunity from the previous infection plus vaccines – they are still vulnerable to the adverse consequences of re-infection,” said Al-Aly, who led the study.
People with repeated infections were more than three times more likely to develop lung problems, three times more likely to suffer from heart disease and 60% more likely to experience neurological disorders than patients who had only been infected once, the study found. The higher risk was most pronounced in the first month after reinfection, but was still pronounced six months later.
The cumulative risk and burden of reinfection increased with the number of infections, even after accounting for differences among COVID-19 variants such as Delta, Omicron and BA.5, the researchers said.
“We were starting to see many patients coming to the clinic with an air of invincibility,” Al-Aly told Reuters. “They wondered: Does getting reinfection really matter?” The answer is yes, it absolutely does.”
Before the fast-approaching holiday season with travel and indoor gatherings, “people should be aware that reinfection is a consequence and should take precautions,” he added.
“We don’t advise drastic measures, but if you’re going on a plane, wear a mask,” Al-Aly said. “If you’re in a supermarket, consider that the person next to you may have a weakened immune system, and if you’re wearing a mask, you could help protect them.