(CNN) Repeatedly catching Covid-19 appears to increase a person’s chance of experiencing new and sometimes permanent health problems after their infection, according to the first study on the health risks of re-infection.
The study, based on the health records of more than 5.6 million people treated at the VA Health System, found that, compared to those with only one Covid-19 infection, those with two or more documented infections more than double the risk. of dying and three times the risk of being in hospital within six months of their last infection. They also had higher risks for lung and heart problems, fatigue, digestive and kidney disorders, diabetes and neurological problems.
The findings come as a new wave of coronavirus variants, particularly BA.5 Omicron, is becoming dominant in the US and Europe, causing cases and hospitals to rise once again. BA.5 caused about 54% of cases nationwide last week, doubling its share of Covid-19 transmission over the past two weeks, according to data posted Tuesday by the US Centers for Disease Control and Prevention.
BA.5 carries key mutations that help it escape antibodies produced by vaccines and previous infection, leaving many people vulnerable to re-infection.
Dr. Ziyad Al-Aly, a clinical epidemiologist at Washington University in St. Louis, led the research, which was posted as a preprint before peer review. He said he decided to do it after watching reinfections become more and more common among his own patients.
“If you asked me about reinfection maybe a year and a half ago, I would have told you maybe I had a patient here or there, but it’s very rare,” said Al-Aly. That’s no longer the case, though.
“So we asked a simple question, if you’ve had Covid before and now you’re on your second infection, does this really add risk? And the simple answer is that it does.”
Calculate the risks of re-infection
Tallying 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 on one occasion with records from another 38,000 people who had two or more documented Covid-19 infections in their medical records. More than 5.3 million people with no record of Covid-19 infection were used as the control group.
Among those with re-infection, 36,000 people had two Covid-19 infections, around 2,200 had contracted Covid-19 three times, and 246 had been infected four times. This may interest you : Catfish River Music Festival to fill the streets of Stoughton with music.
Common new diagnoses after re-infection included chest pain, abnormal heart rhythms, heart attack, inflammation of the heart muscle or the sac around the heart, heart failure and blood clots. Common lung issues included shortness of breath, low blood oxygen, lung disease, and fluid buildup around the lungs, Al-Aly said.
The study found that the risk of a new health problem was highest around the time of re-infection with Covid-19, but also lasted for at least six months. The increased risk was present whether someone had been vaccinated or not, and was graded — meaning it increased with each subsequent infection.
Al-Aly said that’s not what people really think will happen when they get Covid for the second or third time.
“There’s this idea that if you’ve had Covid before, your immune system is trained to recognize it and is better prepared to fight it, and if you get it again, maybe not affects you so much, but it doesn’t. really really,” he said.
Al-Aly said that does not mean that there are not people who have had Covid and have done well; there are many of them. Instead, what his study shows is that each infection brings a new risk, and that risk increases over time, he said.
Even if a person has half the risk of developing permanent health problems during a second infection than they did during their first infection, he says, they still wind up with a 50% greater risk of problems than someone who did not have Covid-19 and second time.
The study has some important caveats. Al-Aly says it is more common to see reinfection among people who had existing risks due to their age or underlying health. That shows that reinfection may not be random, and neither may the health risks associated with reinfection.
“Ill individuals or people with immune dysfunction may be at greater 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 wanted to understand how repeated infections affect the people who get them.
“The most relevant question to people’s lives is, if you get reinfected, does it add to your risk of acute complications and prolonged Covid, and the answer is yes and a clear yes,” he said.
The study is observational, which means it cannot determine cause and effect.
Al-Aly says the researchers saw these increased risks even after they weighted the data to account for the effects of age, sex, medication use and the person’s underlying health before they got Covid-19.
Covid-19 continues to surprise
Experts who were not involved in the research say it is compelling. Read also : East Baton Rouge Parish Receives $ 1 Million for New Mental Health Initiative.
“There’s this idea that I think a lot of people have that ‘if I survived my first infection, I’m actually going to be fine the second time around. There really shouldn’t be any problem,'” said Dr. Daniel Griffin, instructor in clinical medicine at Columbia University.
“The popular wisdom, right, is that reinfection is mild, nothing to worry about, nothing to see here,” Griffin said of the study on the “This Week in Virology” podcast. But that is not actually confirmed, he said.
This is not how it is supposed to work. Even when viruses change shape — as the flu does — our immune system generally retains its memory of how to recognize and fight against certain parts of them. They may still make us sick, but the idea is that our previous immunity is there to put up some sort of defense and keep us from serious harm.
With coronaviruses, and especially SARS-CoV-2 coronaviruses, the hits just keep on coming.
“A year later, you can be re-infected with the same coronavirus a second time. It’s not clear that that second infection can be milder, because coronaviruses inherently have the ability to interfere with lifelong immunity long,” Griffin told CNN.
Griffin says he has seen re-infection of Covid-19 go both ways. Sometimes, the second or third is milder for his patients, but sometimes it is not.
How does that compare to other respiratory infections?
Early in the pandemic, people would get Covid, and three months would pass when they were pretty well protected, he said. But now, those reinfections are happening more often, no doubt because of the rapid changes to the virus. He says he has seen some people infected four times in the last two years.
“We don’t really see a lot of that with the flu,” Griffin said.
As for what people should be doing now regarding this risk, says Dr. Michael Osterholm, who directs the Center for Infectious Disease Research and Policy at the University of Minnesota, that Americans are truly done with the pandemic. That doesn’t mean the pandemic is done with us, though.
Osterholm said he had three close friends who recently went to a restaurant for the first time since the pandemic began. All of them tested positive within 72 hours of that visit to the restaurant.
If you are at higher risk of serious illness or if you want to avoid getting sick, it is a good time to be wearing an N95 mask in public places, he said.
“People don’t want to hear it, but that’s the reality. We’re seeing this resurgence, and we’re seeing increasing numbers of vaccine failures. Obviously, that’s a big concern,” he said.
CNN Health’s Deidre McPhillips contributed to this report.
