Effect of COVID Vaccination on Monthly Migraine Days: a Longitudinal Cohort Study.

Background This longitudinal cohort study aimed to investigate changes in migraine-related outcomes following COVID-19 infection and vaccination. Methods We identified 547 clinically diagnosed migraine patients from the Leiden Headache Center who kept a headache E-diary during the COVID-19 pandemic (February 2020 to August 2022). We sent a questionnaire to register their COVID-19 infection and/or vaccination dates. After applying inclusion criteria, n = 59 participants could be included in the infection analysis and n = 147 could be included in the vaccination analysis. Primary outcome was the change in monthly migraine days (MMD) between 1 month prior and 1 month post COVID-19 infection or vaccination. Secondary outcome variables were change in monthly headache days (MHD) and monthly acute medication days (MAMD). Results Vaccination against COVID-19 was associated with an increase in MMD (1.06; 95% confidence interval [CI] = 0.57–1.55; p < 0.001), MHD (1.52; 95% CI = 0.91–2.14; p < 0.001) and MAMD (0.72; 95% CI = 0.33–1.12; p < 0.001) in the first month post-vaccination. COVID-19 infection solely increased the number of MAMD (1.11; 95% CI = 0.10–1.62; p < 0.027), but no statistically significant differences in MMD or MHD were observed. Conclusions Our findings imply that vaccination against COVID-19 is associated with an increase in migraine, indicating a possible role of inflammatory mediators in migraine pathophysiology.