Low Risk for Recurrent Mild Adverse Events After Reimmunization

An adverse event after immunization may not reoccur with future immunizations, unless the initial reaction was severe.

Patients who experienced an adverse event after immunization are not likely to experience recurrence of such events with future immunizations, unless a severe adverse event after immunization was experienced, according to a review published in Pediatrics.

Individuals should receive all recommended doses of vaccines for full efficacy and to induce long-term protective immunity. Vaccine recipients who experienced an adverse event after immunization are sometimes concerned that the adverse event might recur with future immunizations, which can lead to avoidance or delay of subsequent immunizations. However, most recommendations regarding management of patients who had an adverse event after immunization are based on expert opinion and supported by limited scientific data. There are few studies that evaluate adverse events after immunization recurrence, despite millions of people receiving vaccines annually. Therefore, this study aims to summarize the literature on the risk for adverse event after immunization recurrence and to identify predictors of recurrence. In addition, this study aimed to determine the risk for recurring adverse events after reimmunization.

Using PubMed, Embase, and Cochrane libraries, a systemic review evaluated articles published on or before September 30, 2018, in either English or French that estimated the risk for adverse events after immunization recurrence for at least 5 individuals. Studies with experimental vaccines were excluded. Of 29 articles that were included, data were extracted on the study design, setting, population, vaccines, and adverse events after immunization recurrence. These articles were published between 1982 and 2016; 93% were observational and 48% were prospective. The reported adverse events after immunization were collected through patient and/or parental reports (n=12), physician reports or patient and/or parental reports (n=7), hospital records and/or chart review (n=7), passive surveillance database (n=2), or physician report (n=1).

Results demonstrated that the risk for recurrence of adverse events after immunization (anaphylaxis, seizures, or apnea in terms of infants) was <1%. For more moderate adverse events after immunization (fever, sleepiness, thrombocytopenia, decreased appetite, vomiting, or persistent crying), the risk for recurrence ranged from 4% to 48%. Events occurred at a low rate (0%-0.8%) in patients who were reimmunized and had a history of hypotonic responsive episode (n=398), anaphylaxis (n=133), or seizures (n=60). Allergic-like events recurred in 30 of 594 reimmunized patients. Depending on the vaccine and dose number, fever recurred in 0% to 84% of 836 reimmunized patients. Among children with extensive limb swelling after the fourth dose of diphtheria-tetanus-acellular pertussis vaccine, recurrence was higher when the fifth dose was given with the full-antigen formulation (78%) when compared with the reduced‑antigen formulation (53%; P =.02).

Although many of the studies reviewed included patients who had severe adverse events after immunization and who were not often reimmunized, overall, the study authors concluded that, “[b]ased on the published literature, reimmunization appears to be safe for patients with mild to moderate [adverse events following immunization]. However, the data are insufficient to draw firm conclusions regarding the safety of reimmunization after a severe [adverse event following immunization].”

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Zafack JG, De Serres G, Kiely M, Gariépy MC, Rouleau I, Top KAM. Risk of recurrence of adverse events following immunization: a systemic review. Pediatrics. 2017;140(3):e20163707.