Post-covid medical complaints following infection with SARS-CoV-2 Omicron vs Delta variants

Abstract

The SARS-CoV-2 Omicron (B.1.1.529) variant has been associated with less severe acute disease, however, concerns remain as to whether long-term complaints persist to a similar extent as for earlier variants. Studying 1 323 145 persons aged 18-70 years living in Norway with and without SARS-CoV-2 infection in a prospective cohort study, we found that individuals infected with Omicron had a similar risk of post-covid complaints (fatigue, cough, heart palpitations, shortness of breath and anxiety/depression) as individuals infected with Delta (B.1.617.2), from 14 to up to 126 days after testing positive, both in the acute (14 to 29 days), sub-acute (30 to 89 days) and chronic post-covid (≥90 days) phases. However, at ≥90 days after testing positive, individuals infected with Omicron had a lower risk of having any complaint (43 (95%CI = 14 to 72) fewer per 10,000), as well as a lower risk of musculoskeletal pain (23 (95%CI = 2-43) fewer per 10,000) than individuals infected with Delta. Our findings suggest that the acute and sub-acute burden of post-covid complaints on health services is similar for Omicron and Delta. The chronic burden may be lower for Omicron vs Delta when considering musculoskeletal pain, but not when considering other typical post-covid complaints.

Fig. 1. Flow chart presenting eligible, excluded and included individuals in the main analyses.

PCR polymerase chain reaction. Source data are provided as a Source Data file.

Fig. 2. Risks of complaints from 14 to up to 126 days after SARS-CoV-2 infection with the Omicron variant (n = 13,365), adjusted for age, sex, education, comorbidities, test and care activity and vaccination.

Reference category: persons with SARS-CoV-2 Delta (dashed vertical line) (n = 23,767). Data are presented as Hazard Ratios (HR) with 95% confidence interval (CI) and examined over 8 independent experiments, one for each post-covid outcomes. Blue squares represent the estimates for the Omicron variant compared to the Delta variant. Musc. pain=musculoskeletal pain. Source data are provided as a Source Data file.

Fig. 3. Risks of complaints from 14 to up to 126 days after SARS-CoV-2 infection with the Omicron variant (n = 13,365) and after infection with the Delta variant (n = 23,767), adjusted for age, sex, education, comorbidities, test and care activity and vaccination.

Reference category: persons testing negative (dashed vertical line) (n = 105,297). Data are presented as Hazard Ratios (HR) with 95% confidence interval (CI) and examined over 8 independent experiments, one for each post-covid outcomes. Blue squares represent the estimates for the Delta variant compared to individuals testing negative. Red triangles represent the estimates for the Omicron variant compared to individuals testing negative. Musc. pain=musculoskeletal pain. Source data are provided as a Source Data file.

Fig. 4. Weekly proportions having post-covid complaints per 10 000 individuals in the acute (14–29 days), sub-acute (30–89 days) and chronic (≥90 days) post-covid phases, as distinguished by vertical lines for days 14, 30 and 90.

Data are presented as the number of individuals visiting primary care for the outcome in question at least once a week per 10,000 individuals in each group (coloured lines), with 95% confidence intervals (shaded area). Estimates are predicted probabilities from a logit model with standard errors clustered on person level, adjusted for age, sex, education, comorbidities, test and care activity and vaccination. Source data are provided as a Source Data file.