Rate of Recurrence of Adverse Events Following Immunization: Results of 19 Years of Surveillance In Quebec, Canada.

Authors:
Joseline G Zafack
Joseline G Zafack
Laval University
Eveline Toth
Eveline Toth
Ministère de la santé et des services sociaux du Québec
Monique Landry
Monique Landry
Ministère de la santé et des services sociaux du Québec
Jean-Philippe Drolet
Jean-Philippe Drolet
McGill University
Canada
Karina A Top
Karina A Top
Dalhousie University

Pediatr Infect Dis J 2019 Apr;38(4):377-383

From the Department of Social and Preventive Medicine, Laval University, Quebec, Canada.

Background: While adverse events following immunization (AEFI) are frequent, there are limited data on the safety of reimmunizing patients who had a prior AEFI. Our objective was to estimate the rate and severity of AEFI recurrences.

Methods: We analyzed data from the AEFI passive surveillance system in Quebec, Canada, that collects information on reimmunization of patients who had a prior AEFI. Patients with an initial AEFI reported to the surveillance system between 1998 and 2016 were included. Rate of AEFI recurrence was calculated as number of patients with recurrence/total number of patients reimmunized.

Results: Overall, 1350 patients were reimmunized, of which 59% were 2 years of age or younger. The AEFI recurred in 16% (215/1350) of patients, of whom 18% (42/215) rated the recurrence as more severe than the initial AEFI. Large local reactions extending beyond the nearest joint and lasting 4 days or more had the highest recurrence rate (67%, 6/9). Patients with hypotonic hyporesponsive episodes had the lowest rate of recurrence (2%, 1/50). Allergic-like events recurred in 12% (76/659) of patients, but none developed anaphylaxis. Of 33 patients with seizures following measles mumps rubella with/without varicella vaccine, none had a recurrence. Compared with patients with nonserious AEFIs, those with serious AEFIs were less often reimmunized (60% versus 80%; rate ratio: 0.8; 95% confidence interval: 0.66-0.86).

Conclusions: Most patients with a history of mild or moderate AEFI can be safely reimmunized. Additional studies are needed in patients with serious AEFIs who are less likely to be reimmunized.

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Source
http://dx.doi.org/10.1097/INF.0000000000002162DOI Listing
April 2019
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