The study, which is based on the health records of more than 5.6 million people treated in the VA health system, found that, compared to those who only had a Covid-19 infection, those who had two or more documented infections had more than twice the risk. of dying and three times the risk of being hospitalized in the six months following his last infection. They were also at higher risk for lung and heart problems, fatigue, digestive and kidney disorders, diabetes, and neurological problems.
BA.5 carries key mutations that help it escape the antibodies generated by both vaccines and previous infection, leaving many people vulnerable to reinfection.
“If you asked me about reinfection maybe a year and a half ago, I would tell you that maybe I have a patient here or there, but it’s very, very rare,” Al-Aly said. This is no longer true, however.
“So we asked a simple question that if you used to have Covid and now you’re on your second infection, does that really add risk? And the simple answer is yes.”
Count the risks of reinfections
Al-Aly and his team compared the health records of more than 250,000 people who had tested positive for Covid-19 once with the records of another 38,000 people who had two or more Covid-19 infections documented in their records. doctors. More than 5.3 million people without a record of Covid-19 infection were used as a control group.
Among people with reinfections, 36,000 people had two Covid-19 infections, approximately 2,200 had taken Covid-19 three times, and 246 had been infected four times.
Common new diagnoses after reinfections included chest pain, abnormal heart rhythms, heart attacks, inflammation of the heart muscle or sac around the heart, heart failure, and blood clots. Al-Aly said common lung problems included shortness of breath, low blood oxygen, lung disease, and fluid buildup around the lungs.
The study found that the risk of a new health problem was higher around the time of a Covid-19 reinfection, but it also persisted for at least six months. The increased risk was present whether or not someone had been vaccinated, and graduated, i.e., increased with each subsequent infection.
Al-Aly said this is not what people think will happen when they have Covid for the second or third time.
“There’s this idea that if you had Covid before, your immune system is trained to recognize it and it’s better equipped to fight it, and if you have it again, it may not affect you much, but it’s not. true, ”he said.
Al-Aly said this does not mean that there are no people who have had Covid and have done well; there are many. Rather, what his study shows is that each infection carries a new risk and that risk builds up over time, he said.
Even if a person has half the risk of developing lasting health problems during a second infection than during their first infection, he said, they still end up with a 50% higher risk of problems than someone who did not have Covid- 19 a. second time.
The study has some important warnings. Al-Aly says it was more common to see reinfections among people who had existing risks because of their age or their underlying health. This shows that reinfection may not be random, and it could be that the health risks associated with reinfections are not either.
“People who are sicker or people with immune dysfunction may have a higher risk of reinfection and adverse health outcomes after reinfection,” Al-Aly said.
He was not interested in trying to isolate the pure effects of reinfection, but he wanted to understand how repeated infections are affecting people who suffer from them.
“The most relevant question for people’s lives is, if you reinfect yourself, it adds to your risk of acute and long Covid complications, and the answer is a clear yes and yes,” he said.
The study is observational, meaning it cannot determine cause and effect.
Al-Aly says researchers saw these risks increased even after weighing the data to take into account the effects of the person’s age, sex, drug use and underlying health before taking Covid. -19.
The Covid-19 is still amazing
Experts who did not participate in the investigation say it is convincing.
“There’s this idea that I think a lot of people have that‘ if I survived my first infection, I’ll really be fine the second time. There really should be no problem, ”said Dr. Daniel Griffin, a clinical medicine instructor at Columbia University.
“Popular wisdom, it’s true, is that reinfections are mild, nothing to worry about, nothing to see here,” Griffin said of the study on the podcast “This Week in Virology.” But that is not really being confirmed, he said.
This is not how it should work. Even when viruses change shape, as does the flu, our immune system usually retains the memory of how to recognize and fight them. They can still make us sick, but the idea is that our previous immunity is there to mount some kind of defense and prevent us from serious damage.
With coronaviruses, and especially SARS-CoV-2 coronaviruses, successes keep coming.
“A year later, you can get infected with the same coronavirus for the second time. It’s not clear that this second infection could be milder, because coronaviruses intrinsically have the ability to interfere with long-term immunity.” , Griffin told CNN.
Griffin says he has seen reinforcements for Covid-19 go both ways. Sometimes the second or third is softer for your patients, but sometimes it’s not.
How does this compare to other respiratory infections?
At the start of the pandemic, people would have Covid and spend three months when they were fairly well protected, he said. But now, these reinfections occur more frequently, no doubt due to the rapid changes in the virus. He says he has seen some people infected four times in the last two years.
“We don’t really see that much with the flu,” Griffin said.
As for what people should do now regarding this risk, Dr. Michael Osterholm, who heads the Center for Infectious Disease Research and Policy at the University of Minnesota, says Americans already they have ended the pandemic. That’s not to say the pandemic is over with us, though.
Osterholm said he has three close friends who recently went to a restaurant for the first time since the pandemic began. All of them tested positive in the 72 hours following the visit to the restaurant.
If you’re at higher risk for a serious illness or just want to avoid getting sick, it’s a good time to wear an N95 mask in public places, he says.
“People don’t want to hear it, but that’s the reality. We’re seeing this resurgence and we’re seeing a growing number of vaccine failures. Clearly that’s a major concern,” he said.
CNN Health’s Deidre McPhillips contributed to this report.