Post-covid medical complaints after SARS-CoV-2 Omicron vs Delta variants - a prospective cohort study

Objective To examine whether persons infected with the SARS-CoV-2 omicron variant have an altered risk of post-covid complaints and healthcare use when compared to 1) persons testing negative, and 2) persons with delta. Design Prospective cohort study with 126 days follow-up and a time-to-event approach. Setting A registry-based study including Norwegian residents. Participants All persons aged 18-70 years living in Norway and who had a negative polymerase chain reaction (PCR) test for SARS-CoV-2 (N=105 196, mean (SD) age 42 (14), 50% women)) or positive test with confirmed omicron variant (N=13 028, mean (SD) age 37 (13), 50% women) or delta variant (N=23 368, mean (SD) age 40 (12), 50% women) in December 2021. Individuals with hospital contacts or non-screened PCR test were excluded. Main outcome measures Symptoms/complaints and diagnosis of musculoskeletal pain, fatigue, cough, heart palpitations, shortness of breath, anxiety/depression and brain fog at the general practitioner or emergency ward as recorded in national registries and as observed for the whole follow-up period as well as in periods 14-30 days, 30-90 days and 90 days or more. Results Persons with omicron or delta had similarly increased risk of post-covid fatigue compared to persons testing negative, with a hazard ratio (HR)=1.21 (CI:1.10-1.33) for omicron and HR=1.26 (CI: 1.17-1.35) for delta, for up to 126 days after the test date. They also had an increased risk of shortness of breath (HR=1.43, CI, 1.14-1.80 and HR=1.70, CI, 1.46-1.98 for omicron and delta, respectively, relative to negative). Omicron was related with a similar, and no increased risk of musculoskeletal pain, cough, heart palpitations, anxiety/depression when compared to delta and when compared to test negative. The risk of complaints was similar for omicron and delta and decreased over time for the post-covid periods 14-30 days, 30-90 days and 90 days or more. Conclusions SARS-CoV-2 omicron and delta infection are associated with similarly increased risks of post-covid complaints when compared to non-infected. The omicron variant will likely lead to a temporarily increased burden on healthcare services.