A year after being infected with coronavirus, those affected are much more likely to suffer from typical long Covid symptoms, such as fatigue, than people who have never had a positive PCR test for coronavirus. This greater prevalence cannot be attributed to mental stress as a result of the pandemic. This is shown by the findings of the Swiss Corona Stress Study, conducted with more than 11,000 participants by the University of Basel.
Fatigue, cognitive issues or pain are some of the typical symptoms of long Covid. These symptoms also occur in the general population where there has been no prior infection with the coronavirus SARS-CoV-2, some possibly more frequently due to increased mental stress during the pandemic. This highlights the importance of assessing the prevalence of long Covid symptoms, not just for those who report an infection but also for control subjects without infection. Data from the Swiss Corona Stress Study now enables this comparison.
More than 11,000 people from all over Switzerland took part in the fourth survey, conducted in November 2021 as part of the Swiss Corona Stress Study and led by Professor Dominique de Quervain. In addition to the data on increased mental stress during the pandemic that has already been published, the researchers asked about the presence of a range of physical and neurological symptoms over the two weeks running up to the survey. 744 people stated that they had tested positive on a PCR for SARS-CoV-2 nine months or more (on average 362 days) prior to the survey (98 percent of whom were not admitted to hospital).
Long Covid symptoms for those infected versus control subjects
Several symptoms occurred more frequently among those who had previously tested positive for SARS-CoV-2 than for SARS-CoV-2-negative control subjects (figure 1). The group of control subjects was selected to match the group of SARS-CoV-2-positive people with regard to sociodemographic data such as age, gender or education as well as vaccination status and preexisting mental health conditions.
The most pronounced differences between the two groups of people occurred for the symptoms of loss of taste/smell, rapid physical exhaustion and fever. These symptoms occurred much more frequently in the group of SARS-CoV-2-positive people, regardless of their age or gender. There were other symptoms, however, such as gastrointestinal complaints, which showed no differences between the groups.
No increase in mental stress after infection
Could long Covid symptoms originate from prolonged mental stress following a coronavirus infection? The study showed no indication of this, since there was no difference as regards symptoms of stress or depression between the group with a positive SARS-CoV-2 test and the SARS-CoV-2-negative control group.
The results are from a survey period of 16-28 November 2021. During this period, 11,167 individuals from all over Switzerland took part in the anonymous online survey. The survey was presented as a stress survey taking around 20 minutes. It is therefore possible that people suffering from severe cognitive issues or fatigue may be underrepresented and that these long Covid symptoms have been underestimated.