[Evaluation of the Brazilian surveillance system for adverse events following vaccination]

To describe and evaluate the Brazilian system of passive surveillance of adverse events following immunization (PSAEFI).

The description and evaluation of PSAEFI were undertaken using the reported cases of adverse events following immunization with DTwP-Hib vaccine (AEFI-T), during the period from 2002 to 2005, using the Centers for Disease Control methodology.

The PSAEFI system, which provides national coverage, is designed to standardize practices in cases of adverse events following immunization (AEFI) and to identify highly reactogenic lots of vaccine. The PSAEFI system proved its usefulness, simplicity and flexibility; despite low sensitivity, overestimate the proportion of sever events, but it consistently described AEFI-T, identifying fever, convulsions and hypotonic-hyporesponsive episodes as the most common events. It showed that 49.7% of AEFI-T occur after the first dose, and that 72.8% occur within the first six hours after vaccination. It facilitates public health decisions and epidemiological investigations. It is timely, 46.1% of all AEFI-T being reported within 10 days after vaccination and its completeness ranges from 70 to 90%, depending on the item evaluated.

The PSAEFI system proved useful for monitoring DTwP-Hib vaccine safety. We recommended the incorporation of new methodologies, such the use of sentinel cities/hospitals and computerized immunization registries in order to increase its sensitivity.