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Anaphylaxis rare after vaccination

The incidence of anaphylaxis after vaccine administration is low, but health care providers should be prepared to act in the rare case of onset, according to study results.

Michael M. McNeil, MD, MPH, of the immunization safety office and division of healthcare quality promotion at the National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention in Atlanta and colleagues sought to determine the rate of anaphylaxis after vaccination. The researchers evaluated patients with a vaccination record between January 2009 and December 2011 using data collected from the Vaccine Safety Datalink. They linked the vaccination records to diagnostic and procedure codes to note which anaphylaxis cases had been caused by vaccination.

Overall, the researchers found 33 cases of vaccine-triggered anaphylaxis after analyzing 25,173,965 doses, with a rate of 1.31 per million vaccine doses (95% CI, 0.9-1.84). Specifically, inactivated trivalent influenza comprised 10 cases per 7,434,628 doses (incident rate = 1.35; 95% CI, 0.65-2.47) and inactivated monovalent influenza comprised two cases per 1,090,279 doses (incident rate = 1.83; 95% CI, 0.22-6.63).

Patients who experienced anaphylaxis began to display symptoms within 30 minutes in eight cases, 30 minutes to 120 minutes in eight cases, 2 hours to 4 hours in 10 cases, 4 hours to 8 hours in two cases, with one case identified the following day and four cases left unidentified.

“Our study, which is based on a very large population receiving currently used vaccines, confirms the rarity of postvaccination anaphylaxis overall and after specific vaccines,” McNeil and colleagues wrote. “Although anaphylaxis after immunization is rare, its immediate onset — usually within minutes — and life-threatening nature require that all personnel and facilities providing vaccinations have procedures in place for anaphylaxis management.” – by Jeff Craven

Disclosure: Sukumaran received research support from the National Institutes of Health (NIH); Klein received research, travel support and payment from the CDC for writing and reviewing the manuscript, and has received research support from Sanofi Pasteur, GlaxoSmithKline, Novartis, MedImmune, Protein Science, Merck, Pfizer and Nuron Biotech; Hambidge received research support from the CDC Vaccine Safety Datalink; Lee, King and Jackson received research support from the CDC; Irving received research and travel support from the CDC.