Increased sick leave over a long period after covid-19 infection

Many people have been affected by post-acute symptoms after infection with SARS-CoV-2. For some, these symptoms have been mild and transient, whereas for others, post-acute symptoms have been serious and debilitating. However, the scale of the burden posed by these symptoms for individuals and for society has remained an open question, which a new study from Statens Serum Institut (SSI) has disambiguated.

The study investigated sick leave, which is a good indicator of how serious symptoms have been for people who were infected. The conclusion is clear: a large number of previously infected individuals have reported taking substantial sick leave over a long period of time after infection.

Not mild

The study is part of the large-scale survey on long covid called EFTER-COVID (after Covid). The study is based on data about sick leave from 88,818 Danish residents and investigated how much sick leave persons infected with Covid-19 experienced over a period of eight months after the acute phase of infection had passed.

The researchers then compared these numbers among persons who had no known history of infection. Among persons who were previously infected, 4.5% took more than four weeks of sick leave during the study period. The corresponding number among persons with no known history of infection was only 1.4%.

“These results underscore that post-acute symptoms were not mild and transient for the vast majority, as many hoped earlier on during the pandemic,” said professor and department head Anders Hviid, who led the study.

“In the present study, we look at Danes who were infected between November 2020 and February 2021. Since we have observed fewer post-acute symptoms after vaccination and infection with the omicron variant, we also expect that less sick leave will be associated with infection later in the pandemic,” Hviid continued.

Who was most affected?

The researchers also investigated which groups took the most sick leave associated with previous infection. Here, there were clear differences: women, older adults, and persons with a high body mass index (BMI) took more sick leave than men, younger adults, and persons with normal-ranged BMI. In addition, having pre-existing conditions before infection played a significant role. Persons with pre-existing fibromyalgia, diabetes, and lung diseases seemed to be particularly affected.

The study is available on a pre-print server but has not yet been peer-reviewed.