US doctors have discovered that a significant proportion of patients who have had influenza in the recent past develop a set of long-term negative consequences of the virus infection, similar to the manifestations of post-coital syndrome. The scientists' findings were published in an article in the scientific journal The Lancet Infectious Diseases.

"We were interested in how often and severely over-infected people with influenza suffer long-term consequences of contracting the virus. It turned out that the flu is similar in this respect to COVID-19, and in many cases, the long-term consequences of its development turned out to be more serious than the difficulties that patients endured in the first phases of the infection," - said Associate Professor of Medical School of Washington University in St. Louis Ziyad Al-Ali, whose words quotes the press service of the journal.

Many people who have had a coronavirus infection suffer from postcovirus syndrome over the next few months. This is characterized by chronic fatigue, hair loss, shortness of breath, and exacerbation of many chronic diseases, which increases the risk of premature death and is thought to be related to a constantly high activity of the immune system.

Researchers have found that something similar is characteristic of influenza. Scientists came to this conclusion when studying the medical histories of more than 81,000 people who had a coronavirus infection in 2020-2022, as well as almost 11,000 patients who had influenza between October 2015 and February 2019. Researchers analyzed how often both study participants subsequently went to the hospital, as well as died or suffered severe illness.

In this analysis, the researchers found that infection with both viruses significantly increased the risk of developing long-term health problems after the patients had recovered. Specifically, covid patients often suffered from 64 different long-term health problems, including circulatory, bowel, and kidney problems, while influenza contributed to type 1 diabetes, tachycardia, hypoxemia, and three types of lung problems. All of these significantly increased the patients' risk of dying in the next 18 months of their lives.

"Before the pandemic, we took respiratory viral infections too lightly and thought they were an inconsequential problem that would go away on its own within days of infection. We are now uncovering evidence that this is not the case for all over-infected people: many patients develop serious long-term consequences after infection, and we need to realize this and start taking these viral infections seriously," Al-Ali concluded.