A nationwide questionnaire study of post-acute symptoms and health problems after SARS-CoV-2 infection in Denmark

Abstract

A considerable number of individuals infected with SARS-CoV-2 continue to experience symptoms after the acute phase. Here, we report findings from a nationwide questionnaire study in Denmark including 61,002 RT-PCR confirmed SARS-CoV-2 cases and 91,878 test-negative controls aged 15-years or older. Six to twelve months after the test, the risks of 18 out of 21 symptoms were elevated among test-positives. The largest adjusted risk differences (RD) were observed for dysosmia (RD = 10.92%, 95% CI 10.68-11.21%), dysgeusia (RD = 8.68%, 95% CI 8.43-8.93%), fatigue/exhaustion (RD = 8.43%, 95%CI 8.14-8.74%), dyspnea (RD = 4.87%, 95% CI 4.65-5.09%) and reduced strength in arms/legs (RD = 4.68%, 95% CI 4.45-4.89%). During the period from the test and until completion of the questionnaire, new diagnoses of anxiety (RD = 1.15%, 95% CI 0.95-1.34%) or depression (RD = 1.00%, 95% CI 0.81-1.19%) were also more common among test-positives. Even in a population where the majority of test-positives were not hospitalized, a considerable proportion experiences symptoms up to 12 months after infection. Being female or middle-aged increases risks.

Fig. 1. Risk differences of symptoms after 6–12 months, comparing SARS-CoV-2 test-positive and test-negative participants.

Note: Bars indicate risk differences (center) with 95% confidence intervals (length of error bars) adjusted for age, sex, comorbidities, obesity, healthcare occupation, and time after testing (in months). For post-acute symptoms 6–12 months after the test date, all test negatives no matter the indication for testing are used as the control population. All symptom questions were mandatory, so for all lines the proportions are based on 61,002 test-positive and 91,878 test-negative individuals. An individual could only participate in the study once, as either test-positive or test negative.

Fig. 2. Risk differences of self-reported new diagnoses received between the test date and until 6-12 months after, comparing SARS-CoV-2 test-positive and test-negative participants.

Note: Bars indicate risk differences (center) with 95% confidence intervals (length of error bars) adjusted for age, sex, comorbidities, obesity, healthcare occupation and time after testing (in months). PTSD = post-traumatic stress disorder. For diagnoses with onset between the test date and until 6–12 months after the test date, all test negatives no matter of the indication for testing are used as control population. All symptom questions were mandatory, so for all lines the proportions are based on 61,002 test-positive and 91,878 test-negative individuals. An individual could only participate in the study once, as either test-positive or test negative.

Fig. 3. Risk differences of self-reported health problems with new onset between the test date and until 6–12 months after, comparing SARS-CoV-2 test-positive and test-negative participants.

Note: Bars indicate risk differences (center) with 95% confidence intervals (length of error bars) adjusted for age, sex, comorbidities, obesity, healthcare occupation, and time after testing (in months). For health problems with onset between the test date and until 6–12 months after the test date, all test negatives no matter of the indication for testing are used as control population. All symptom questions were mandatory, so for all lines the proportions are based on 61,002 test-positive and 91,878 test-negative individuals. An individual could only participate in the study once, as either test-positive or test negative.

Fig. 4. Risk differences of symptoms after 6-12 months, comparing SARS-CoV-2 test-positive and test-negative participants, stratified by sex and age group.

Note: Risk differences (center) with 95% confidence intervals (width of error bands) were adjusted for comorbidities, obesity, healthcare occupation, and time after testing (in months).