COVID-19 Vaccine Adverse Events by Country Income Level: A Systematic Review and Meta-Analysis of Randomized...

Area of Science:

• Immunology
• Public Health
• Epidemiology

Background:

• The global rollout of COVID-19 vaccines has been accompanied by monitoring for adverse events following immunization (AEFI).
• Understanding potential disparities in AEFI incidence across different socioeconomic settings is crucial for equitable global health strategies.

Purpose of the Study:

• To systematically review and meta-analyze the incidence of COVID-19 vaccine-related adverse events.
• To compare AEFI rates across countries based on their income levels.

Main Methods:

• A systematic review and meta-analysis of eleven randomized controlled trials (RCTs) published between 2020 and 2025.
• Studies were retrieved from EMBASE, PubMed/MEDLINE, and Scopus, including data from high-income and upper-middle-income countries.
• Mantel-Haenszel random-effects models were used to estimate relative risks (RR) for AEFI, with subgroup analyses conducted by country income and vaccine dose.

Main Results:

• AEFI incidence was significantly higher in high-income countries compared to upper-middle-income countries, particularly after the second vaccine dose.
• Common adverse events included injection-site pain, headache, myalgia, and fatigue, with higher reported rates in high-income settings.
• Meta-analyses revealed higher pooled relative risks for any AEFI, local reactions, and systemic reactions in high-income countries, with mRNA vaccines showing the highest incidence rates.

Conclusions:

• Higher-income countries experienced a greater incidence of generally mild adverse events following COVID-19 vaccination, with a notable increase after the second dose.
• These findings underscore significant income-based disparities in vaccine adverse event reporting.
• The results provide valuable insights for developing equitable post-vaccination surveillance and monitoring systems globally.