Objectives: There is a lack of large studies on long-COVID symptoms with symptoms measurements before the onset of COVID-19. Therefore, long-COVID is still poorly defined.
Methods: The Norwegian COVID-19 Cohort Study is a population-based, open cohort of adult participants (aged 18-96 years) from Norway. From March 27, 2020, participants were recruited through social media, invitations, and nationwide media coverage. Fourteen somatic and cognitive symptoms were assessed at baseline and four follow-ups for up to 22 months. SARS-CoV-2 test status was obtained from a mandatory national registry or from self-report.
Results: After follow-up, 15 737 participants had a SARS-CoV-2-positive test, 67 305 had a negative test, and 37 563 were still untested. Persistent symptoms reported more frequently by positive compared with negative participants one month after infection, were memory problems (3-6 months: adjusted odds ratio (aOR) = 6.8, CI = 5.7-8.1; >18 months: aOR = 9.4, CI = 4.1-22), and concentration problems (3-6 months: aOR = 4.1, CI = 3.5-4.7; >18 months: aOR = 4.4, CI = 2.0-9.7) as well fatigue, dyspnea, anosmia and dysgeusia.
Conclusions: COVID-19 was associated with cognitive symptoms, anosmia, dysgeusia, dyspnea, and fatigue as well as worsening of overall health up to 22 months after a SARS-CoV-2 test, even when correcting for symptoms before the onset of COVID-19.
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