Post-vaccination headache reporting: Trends according to the Vaccine Adverse Events Reporting System

Area of Science:

• Vaccinology
• Pharmacovigilance
• Epidemiology

Background:

• Headache is a frequently reported symptom after vaccination.
• Systematic analysis of post-licensure headache reports is lacking.
• Understanding these events is crucial for vaccine safety monitoring.

Purpose of the Study:

• To assess the characteristics of headache as an adverse event following vaccination.
• To evaluate the associated disability and demographic factors.
• To analyze trends in a national surveillance system.

Main Methods:

• Retrospective analysis of the Vaccine Adverse Events Reporting System (VAERS) database.
• Data collected from July 1990 to June 2020.
• Evaluation of epidemiological features, patient demographics, and vaccine types.

Main Results:

• Headache was the fifth most reported adverse symptom (8.1%) in individuals aged 3+ years.
• Most headache reports were non-serious, with a minority involving hospitalization (6.1%) or permanent disability (2.5%).
• Commonly associated with herpes zoster and influenza vaccines, predominantly affecting females and individuals aged 6-59 years.

Conclusions:

• Headache is a common post-vaccination adverse event, with a small serious subset.
• Standardized vaccine-related case definitions are needed for better evaluation.
• Improved definitions may reduce vaccine hesitancy in headache-prone individuals.