Characterization of post-COVID syndromes by symptom cluster and time period up to 12 months post-infection: A systematic review and meta-analysis

•A subset of individuals continues to report post-COVID symptoms beyond one year.•Studies reporting post-COVID symptom clusters remain rare in the literature.•We identified systemic inflammatory, cardiorespiratory, and neurologic clusters.•Reporting of post-COVID symptom clusters is key to understanding long COVID. The objective of this study was to characterize post-COVID condition symptoms and symptom clusters, their duration, and prevalence. We conducted a systematic review and random-effects meta-analysis of studies reporting post-COVID-19 symptoms and clusters, respectively. We searched MEDLINE (via PubMed), Scopus, Web of Science, Science Direct, Google Scholar, EBSCOhost, EMBASE, PsycINFO, Cochrane Library, and Mednar for literature reporting on the post-COVID condition up to August 2022. In the 76 included studies, we found that although most symptoms were reported less frequently 7-12 months after infection compared to earlier, over 20% of patients reported at least one post-COVID condition-compatible symptom. In the seven studies reporting post-COVID symptom clusters, neurological clustering was consistently identified, followed by cardiorespiratory and systemic/inflammatory. Post-COVID symptom clustering provides direction for research into the etiology, diagnosis, and management of post-COVID conditions. Studies reporting post-COVID symptom clusters remain rare due to the focus on individual symptom reporting. Studies on post-COVID symptom clusters should replace individual symptom reporting to accelerate our understanding of this emerging public health issue.