Cheta, Nicholas, Zakaria, Dianne, Demers, Alain et al. · BMC public health · 2025 · DOI
This Canadian study looked at whether people with long-term health conditions experienced more severe COVID-19 symptoms when they caught the virus. Researchers surveyed over 10,000 adults from 2020 to 2022 and found that certain conditions—like chronic lung disease, high blood pressure, ME/CFS, fibromyalgia, and arthritis—were linked to worse COVID-19 symptoms. This information can help doctors identify who might need extra support or preventive care when facing a COVID-19 infection.
ME/CFS and fibromyalgia patients showed more than double the odds of severe COVID-19 symptoms compared to those without these conditions, highlighting a specific vulnerability in this population. Understanding which pre-existing conditions increase COVID-19 severity risk can inform targeted prevention strategies and early interventions for ME/CFS patients, who may benefit from enhanced monitoring or preventive treatments during infection.
This study cannot prove that chronic conditions directly cause more severe COVID-19; it only demonstrates associations in a specific population. The reliance on self-reported symptom severity (rather than objective clinical measures) may introduce recall bias or misclassification. Cross-sectional design prevents determination of temporal relationships and cannot establish causation.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
Spotted an error in this entry? Report it →