This was discovered by an American research team by analyzing the medical records of about half a million people who tested positive one, two, three or four times in Sars-Cov-2.
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Since the outbreak of the Covid pandemic, it has immediately become clear that a first infection can have important health consequences, in the short and long term. But what are the risks of a second, third or fourth infection that, with the relaxation of restrictions and the emergence of new viral strains capable of evading part of the immune response, are increasingly frequent in the population? This was discovered by a research team from Washington University School of Medicine in St. Louis, Missouri, who evaluated it the risks associated with Sars-Cov-2 reinfections analyzing about half a million medical records present in the health database of the US Department of Veterans Affairs Health Care of people who tested positive once, twice or more times for Sars-Cov-2.
Specifically, the scholars examined the clinical information of 443,588 people infected with Sars-Cov-2, of which about 41,000 were found twice or more positive times at least 90 days apart from the first infection, between March 2020 and April 6, 2022, comparing these data with those of 5.3 million people who did not contract Covid in the same period of time. At the time of the study, among those who had experienced reinfection, most people had had two or three infections (92.8% and 6.3% respectively)0.9% had had four infections, and none had five or more infections.
Reinfections increase the risk of health problems
The study, published in detail in the scientific journal Nature Medicine, examined the health risks of reinfections within the first 30 days of positivity and up to six months, taking into account the different variants in circulation, such as Delta and Omicron and BA.5. Overall, the analysis found that people who have experienced reinfection have three times more likely to be hospitalized, three times more likely to have cardiovascular problems, and three times more likely to develop blood clotswith a double chance of death compared to people infected only once with Sars-Cov-2.
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In addition, people with reinfections were significantly more likely to develop lung, gastrointestinal, diabetes, renal, musculoskeletal disorders, and experience neurological consequences. “Such risks – scholars explain – they were evident regardless of the vaccination statusand were most pronounced in the acute phase, while persisting in the post-acute phase at six months“. Compared to people who have never contracted Covid, the consequences of reinfection have increased based on the number of infections.
“In recent months, there has been an air of invincibility among people who have had Covid, vaccines and boosters, especially among those who have had an infection. Someone has begun to believe these people as holders of a kind of superimmunitybut is not so Said Dr. Ziyad Al-Aly, senior author of the study and clinical epidemiologist at Washington University School of Medicine in St. Louis. Unambiguously, our research has shown that contract the infection a second, third or fourth time contributes to additional health risks in the acute phase, i.e. the first 30 days after infection, and in the following months, i.e. during the Long Covid phase”.