Childhood Immunizations

Reimmunization Is Safe for Infants, Children

Reimmunization is safe for infants and children who have had a prior adverse event following immunization, according to the results of a new analysis.


The researchers came to this conclusion after reviewing data collected from the AEFI passive surveillance system from 1998 to 2016. The system collects data about reimmunization of individuals who have had an adverse event following immunization in Quebec, Canada.



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Between 1998 and 2016, 1350 individuals were reimmunized, the majority of whom were younger than age 2 years.


Results of the analysis showed that 215 out of 1350 participants had experienced a recurrent adverse event following immunization, and 18% of those with recurrences reported the recurrence to be worse than the initial event.


The most common adverse event reported was large local reactions extending beyond the nearest joint and lasting 4 days or more.


Participants reporting serious adverse events following immunization were less often reimmunized, compared with those reporting non-serious adverse events following immunization.


“Most patients with a history of mild or moderate [adverse event following immunization] can be safely reimmunized,” the researchers concluded. “Additional studies are needed in patients with serious [adverse events following immunization] who are less likely to be reimmunized.”


—Amanda Balbi



Zafack JG, Toth E, Landry M, Drolet JP, Top KA, De Serres G. Rate of recurrence of adverse events following immunization: results of 19 years of surveillance li Quebec, Canada [published online September 10, 2018]. Ped Inf Dis J. doi:10.1097/INF.0000000000002162.