Assessment of sex-specific differences in adverse events following immunization reporting in Ontario, 2012–15

Highlights:

• Sex differences in AEFI reporting within passive surveillance systems are not well understood.

• We assessed sex-specific trends in passive AEFI surveillance in Ontario, Canada over four years. We observed overall predominance of female AEFI reports that varied by age, vaccine and reaction.

• Our findings support that both biological and behavioural factors may explain these differences.

• Further study is needed to characterize the relationship between sex, gender and AEFI reporting.