Spontaneous reporting of adverse events following pandemic influenza A (H1N1) immunization in a reference center in the State of São Paulo, Brazil

Abstract

Introduction  This paper describes adverse events (AEs) temporally associated to the pandemic influenza A (H1N1) vaccine observed in a reference center in São Paulo, Brazil, during a 2010 mass vaccination campaign.

Methods  A retrospective study involving persons who sought medical care for AEs following influenza vaccination. Data were retrieved from medical records, vaccine AE notification forms, and a computerized system for immunobiological registration.

Results  Sixty-six vaccinees sought medical care for AEs after immunization. The most frequent AEs were fever, headache, myalgia, and pain at the injection site. No serious AEs were reported.

Conclusions  Few vaccinees spontaneously reported AEs to influenza A (H1N1) vaccine at this center.

Pandemic influenza A (H1N1); Influenza vaccines; Adverse events following immunization