Headache After Vaccination: An Update on Recent Clinical Trials and Real-World Reporting

PURPOSE OF REVIEW: The aim of this review is to characterize headache as a vaccine adverse event (VAE) in clinical trials. RECENT FINDINGS: Of the recent phase III vaccine RCTs (non-COVID-19), 53 studies reported on headache (13 infectious agents). The median rate (interquartile range) of headache was 15.6% (IQR: 9.6–37.6%). Of these, 24.5% of the RCTs reported headache greater in the vaccine group compared to the placebo/control group. In the herpes zoster vaccination trials, headache was more common in all active groups: median rate 33.9% (IQR: 29.7–40.5%) as compared to placebo: median rate 17.7% (IQR: 15.4–23.8%). Influenza and HPV vaccination trials were the 2nd and 3rd most common to have headache as a VAE. Of the 6 widely distributed COVID-19 vaccinations, median rate of post-vaccination headache was 39% (IQR: 28–50%). SUMMARY: Headache is a common VAE in vaccine trials. Standardized grading methods, predictors of persistence, and treatment regimens are warranted.