Global Prevalence of Long COVID, its Subtypes, and Risk factors: An Updated Systematic Review and Meta-Analysis

Abstract Background This mega-systematic review evaluated the global prevalence of long COVID, its subtypes and symptoms, and assessed the effects of risk factors for long COVID. Methods Studies published from July 5, 2021, to May 29, 2024, were searched in PubMed, Embase, and Web of Science, with supplemental updates on July 23, 2024. Data were pooled using a random-effects framework with DerSimonian-Laird estimator. Risk of bias analysis was conducted. Results A total of 429 studies were meta-analyzed. The global pooled long COVID prevalence was 36% (95% confidence interval CI 33%-40%) with 144 contributing studies. The highest prevalence rates were observed in South America (51% 95% CI 35%-66%). The prevalence of long COVID persists over time, with 35% (95% CI 31%-39%) at less than one-year follow-up and 46% (95% CI 37%-57%) at one to two years. The most prevalent subtypes were respiratory (20% 95% CI 14%-28%) estimated from 31 studies, general fatigue (20% 95% CI 18%-23%) from 119 studies, psychological (18% 95% CI 11%-28%) from 10 studies, and neurological (16% 95% CI 8%-30%) from 23 studies. The three strongest risk factors were unvaccinated for COVID-19 (pooled odds ratio (OR) 2.09 95% CI 1.55-2.81) meta-analyzed from 7 studies, infections from pre-Omicron variants (OR 1.74 95% CI 1.40-2.17) from 6 studies, and female sex (OR 1.56 95% CI 1.32-1.84) from 33 studies. Conclusions Long COVID is globally prevalent after a COVID-19 infection, highlighting a continuing health challenge. The heterogeneity of estimates across populations argues the need for well-designed follow-up studies that use consistent measures and are globally representative.