E2 ModerateModerate confidencePEM not requiredObservationalPeer-reviewedMachine draft
Association between quadrivalent human papillomavirus vaccination and selected syndromes with autonomic dysfunction in Danish females: population based, self-controlled, case series analysis.
Hviid, Anders, Thorsen, Nicklas M, Valentiner-Branth, Palle et al. · BMJ (Clinical research ed.) · 2020 · DOI
Quick Summary
This study examined whether the HPV vaccine (used to prevent cervical cancer) was linked to ME/CFS, complex regional pain syndrome, or POTS in over 1.3 million Danish girls and women. Researchers found no evidence that the vaccine caused these conditions—the rates of these illnesses were similar whether or not girls received the vaccine.
Why It Matters
Given ongoing public concerns about HPV vaccination and autonomic dysfunction, this large-scale registry study provides reassuring population-level evidence regarding ME/CFS and related conditions. For patients questioning vaccine safety in relation to illness onset, this evidence helps inform shared decision-making with healthcare providers.
Observed Findings
- 869 cases of autonomic dysfunction syndromes were identified (136 ME/CFS, 535 CRPS, 198 POTS) across 10.6 million person-years of follow-up.
- Composite outcome rate ratio was 0.99 (95% CI 0.74-1.32) in the 365-day post-vaccination period.
- ME/CFS individually showed lower rates post-vaccination (RR 0.38, 95% CI 0.13-1.09).
- Complex regional pain syndrome and POTS showed no significant associations with vaccination timing.
Inferred Conclusions
- Quadrivalent HPV vaccination does not appear to cause a causal increase in ME/CFS, CRPS, or POTS rates at the population level.
- Temporal clustering of autonomic dysfunction diagnoses and HPV vaccination could occur by chance alone without causal relationship.
- Current evidence does not support a link between HPV vaccination and these autonomic syndromes.
Remaining Questions
- Could smaller individual risk elevations (below 32%) exist that larger studies might detect?
- Do specific subgroups (age, genetic predisposition, prior infections) face higher risks despite no overall population signal?
- Could diagnostic delays or misclassification in registry codes obscure true cases?
What This Study Does Not Prove
This study does not prove vaccines cannot trigger ME/CFS or autonomic conditions in any individual—it shows population-level rates were not elevated. The study cannot exclude smaller increased risks (up to 32% above baseline) due to statistical power limitations. Registry-based diagnosis codes may miss cases or misclassify conditions, so true associations in undiagnosed populations cannot be ruled out.
Tags
Symptom:Orthostatic IntolerancePainFatigue
Phenotype:Pediatric
Method Flag:Weak Case DefinitionMixed Cohort
Metadata
- DOI
- 10.1136/bmj.m2930
- PMID
- 32878745
- Review status
- Machine draft
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 8 April 2026
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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