Lower prevalence of Post-Covid-19 Condition following Omicron SARS-CoV-2 infection

Abstract

ABSTRACTBackgroundDifferent SARS-CoV-2 variants can differentially affect the prevalence of Post Covid-19 Condition (PCC). This prospective study assesses prevalence and severity of symptoms three months after an Omicron infection, compared to Delta, test-negative and population controls. This study also assesses symptomology after reinfection and breakthrough infections.MethodsAfter a positive SARS-CoV-2 test, cases were classified as Omicron or Delta based on ≥ 85% surveillance prevalence. Population controls were representatively invited and symptomatic test-negative controls enrolled after a negative SARS-CoV-2 test. Three months after enrolment, participants indicated point prevalence for 41 symptoms and severity of four symptoms. Permutation tests identified significantly elevated symptoms in cases compared to controls. PCC prevalence was estimated as the difference in prevalence of at least one elevated symptom in cases compared to population controls.FindingsAt three months follow-up, five symptoms and severe dyspnea were significantly elevated in Omicron cases (n = 4138) compared to test-negative (n= 1672) and population controls (n= 2762). PCC prevalence was 10·4% for Omicron cases and 17·7% for Delta cases (n = 6855). Prevalence of severe fatigue and dyspnea were higher in reinfected compared to primary infected Omicron cases, while severity of symptoms did not significantly differ between Omicron cases with a booster or primary vaccination course.InterpretationThree months after Omicron, prevalence of PCC is 41% lower than after Delta. Reinfection seems associated with more prevalent severe long-term symptoms compared to a first infection. A booster prior to infection does not seem to improve the outcome of long-term symptoms.FundingThe study is executed by the National Institute for Public Health and the Environment by order of the Ministry of Health, Welfare and Sport.