How bad is it to get corona more than once? – New Scientist

According to new research, people who have had Covid-19 more than once are at twice the risk of dying from any cause, compared to people who have tested positive only once.

You have been vaccinated and have recently had covid-19, so you don’t have to worry about getting it again. However? wrong. A new study points out that each new infection carries additional health risks, both during the illness and in the months after.

“Any reinfection is like rolling a die again,” said Ziyad Al-Aly, assistant professor of medicine at Washington University School of Medicine in the United States. “A second infection is just as bad for you as a first.”

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Twice the chance of death

These findings are especially concerning because the omikron subvariants BA.4 and BA.5, which are driving the latest wave in much of the world, are even better at evading previous immunity than the BA.1 and BA.2 -subvariants of the first omikron waves. As a result, many millions of people worldwide could be reinfected in the coming weeks.

The research received a lot of attention online when it was released as a pre-publication on June 17. Among other things, it found that people who had had Covid-19 twice or more were twice as likely to die from any cause in the six months after contracting the coronavirus, compared to people who had contracted it only once. . They were also three times more likely to be hospitalized during that period.

This result was misinterpreted by many people. They saw it as a sign that reinfections are inherently worse than first infections. But that is absolutely not the case, says Al-Aly.

Reinfection Severity

The risk of serious consequences after reinfection is probably less than after the first infection, he says. We don’t know for sure, though, because the study didn’t compare the first and second infection among the same individuals. Instead, the researchers compared people who had been infected at least twice with people who had experienced one infection. It could be that people who become infected twice are relatively vulnerable and therefore more likely to be severely affected, Al-Aly says.

Another interpretation that is also given to the research is that it is worse to get Covid-19 two or three times than just once. This is, to a certain extent, true. That sounds obvious to some, but there are also people who assume that reinfections are harmless. Until now, however, no one had quantified the effect of reinfections, Al-Aly says. Nor had it been shown how much worse people are in six months after reinfection.

Cumulative Risk

In the study, people who had covid-19 two or three times scored significantly higher on unpleasant things, from heart disease to kidney disease, compared to people who had experienced just one infection. This was true during the first thirty days of infection, and in the months that followed. This suggests a cumulative increase in risk. This applies to unvaccinated as well as those who had received at least one dose of vaccine for their second corona infection.

The study is based on the medical records of nearly six million people maintained by the United States Department of Veterans Affairs. Of these people, nearly 260 thousand had one covid-19 infection, and 40 thousand had two or more.

In the study, the average age of the people was 60, but there were also people in their 20s, says Al-Aly, who doesn’t think the results apply only to older people.

Global burden of disease

One criticism of the study is that reinfection was defined as a positive test thirty days or later after a previous positive test. Such a positive result could also be the result of the initial infection, rather than a reinfection. That criticism is completely justified, says Al-Aly. The team has since re-analyzed the data, looking only for positive tests that occurred at least 90 days after the first. The results were essentially the same, he says.

In fact, the findings from this study shouldn’t come as much of a surprise, given what we know about the risk of reinfection with other viruses. For example, flu reinfections occasionally cause serious complications, from heart inflammation to multiple organ failure, especially in older people. These reinfections lead to a huge global burden of disease. It would therefore not be surprising if, at least in the coming years, the disease burden due to Covid-19 increases further due to the higher number of reinfections and the possibly greater risks after each reinfection.

Preventive treatments

Now that we know this, what should we do? Since there is less enthusiasm for wearing masks and limiting social contacts, Al-Aly believes that we should treat more people preventively with antiviral drugs such as Pfizer’s paxlovid (which consists of the generic drugs niramatrelvir and ritonavir), and that we must prioritize the development of more effective vaccines, such as vaccines administered through the nose.

“There is no excuse not to hyper-aggressively pursue these vaccines,” wrote cardiologist Eric Topol of the Scripps Research Translational Institute in the United States, commenting on Al-Aly’s research. “The lack of urgency and the lack of resources comes from the illusion that the pandemic is behind us.”

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