Postacute symptoms 4 months after SARS-CoV-2 infection during the Omicron period: a nationwide Danish questionnaire study

• Published in: American journal of epidemiology 2024-08, Vol.193 (8), p.1106-1114
• Main Authors: Spiliopoulos, Lampros, Sørensen, Anna Irene Vedel, Bager, Peter, Nielsen, Nete Munk, Hansen, Jørgen Vinsløv, Koch, Anders, Meder, Inger Kristine, Videbech, Poul, Ethelberg, Steen, Hviid, Anders
• Format: Article
• Language: English
• Subjects: Original Contribution
• ISSN: 0002-9262; 1476-6256; 1476-6256
• DOI: 10.1093/aje/kwad225

Postacute symptoms are not uncommon after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with pre-Omicron variants. How the Omicron variant and coronavirus disease 2019 (COVID-19) booster vaccination influence the risk of postacute symptoms is less clear. We analyzed data from a nationwide Danish questionnaire study, EFTER-COVID, comprising 36 109 individuals aged ≥15 years who were tested between July 2021 and January 2022, to evaluate the associations of the Omicron variant and COVID-19 booster vaccination with postacute symptoms and new-onset general health problems 4 months after infection with SARS-CoV-2. Risk differences (RDs) were estimated by comparing Omicron cases with controls, comparing Omicron cases with Delta cases, and comparing Omicron cases vaccinated with 3 doses with those vaccinated with 2 doses, adjusting for age, sex, body mass index, self-reported chronic diseases, Charlson comorbidity index, health-care occupation, and vaccination status. Four months after testing for SARS-CoV-2 during the Omicron period, cases experienced substantial postacute symptoms and new-onset health problems in comparison with controls; the largest RD was observed for memory issues (RD = 7.4%; 95% CI, 6.4-8.3). However, risks were generally lower than those in the Delta period, particularly for dysosmia (RD = –15.0%; 95% CI, −17.0 to −13.2) and dysgeusia (RD = –11.2%; 95% CI, −13.2 to −9.5). Booster vaccination was associated with fewer postacute symptoms and new-onset health problems 4 months after Omicron infection as compared with 2 doses of COVID-19 vaccine.