Background: The safety of COVID-19 vaccines has been demonstrated in selected populations in recent studies, but more data in specific groups is needed to inform vaccine choice and health policy. Objectives: An international, online survey was conducted to compare the safety, tolerability and reactogenicity of available COVID-19 vaccines in different recipient groups. Methods: This survey was launched in February 2021, for 11 days. Recipients of a first COVID-19 vaccine dose [≥]7 days prior to survey completion were eligible. The incidence and severity of vaccination side effects were assessed. Results: Survey was completed by 2,002 respondents, of whom 26.6% had prior COVID-19 infection (68.8% laboratory confirmed). Prior COVID-19 infection was associated with increased risk of any side effect (risk ratio 1.08, 95% confidence intervals [1.05-1.11]), fever (2.24 [1.86-2.70]), breathlessness (2.05 [1.28-3.29]), flu-like illness (1.78 [1.51-2.10]), fatigue (1.34 [1.20-1.49]) and local reactions (1.10 [1.06-1.15]). It was also associated with increased risk of severe side effects, leading to hospital care (1.56 [1.14-2.12]). While mRNA vaccines were associated with a higher incidence of any side effect (1.06 [1.01-1.11]) compared to viral vector-based vaccines, these were generally milder (p<0.001), mostly local reactions. Importantly, mRNA vaccine-recipients reported considerably lower incidence of systemic reactions (RR<0.6) including anaphylaxis, swelling, flu-like illness, breathlessness and fatigue, and of side effects requiring hospital care (0.42 [0.31-0.58]). Conclusion: For the first time, our study links prior COVID-19 illness with increased incidence of vaccination side effects and demonstrates that mRNA vaccines cause milder, less frequent systemic side effects, but more local reactions.
Self-reported real-world safety and reactogenicity of COVID-19 vaccines: An international vaccine-recipient survey.