Hsu, Han-Jen, Chang, Hsun, Lin, Cheng-Li et al. · Journal of infection and public health · 2024 · DOI
This study found that people who have pneumonia are about 1.4 times more likely to develop ME/CFS compared to people who don't have pneumonia. The risk was higher for certain types of bacterial and viral infections, including specific bacteria like Pseudomonas and Streptococcus pneumoniae, as well as influenza virus. The researchers used health records from 2 million adults in Taiwan to track whether pneumonia patients developed ME/CFS over time.
This is one of the few large-scale studies quantifying the association between a specific respiratory infection (pneumonia) and subsequent ME/CFS development, providing epidemiological evidence that infections may trigger post-infectious ME/CFS in susceptible individuals. Understanding which pathogens carry higher risk could help identify vulnerable patients who need early monitoring and intervention after pneumonia.
This study demonstrates correlation between pneumonia and CFS development but does not prove causation—selection bias, unmeasured confounders, or reverse causality (pre-existing immune dysfunction predisposing to both) could explain the association. The study also cannot determine whether the observed CFS diagnoses meet strict international diagnostic criteria, as it relies on diagnostic codes in claims data. Finally, it does not identify the biological mechanisms linking infection to CFS onset.
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 →
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