PP10.12 – 2525: Neurological adverse events following immunization (AEFI): Brazilian data

Abstract

Objective Despite the benefits of vaccines, it is well recognized that some cases of AEFI occur; among them, adverse events that affect the nervous system are that cause more concern. The nervous system can be affected directly by vaccines' antigens, or by inflammatory processes triggered by them. Herein we describe all the neurological AEFI reported to the Ministry of Health (MoH) surveillance system in the period from 2008 to 2013 in Brazil. Methods A retrospective study based on the AEFI data from 2008 to 2013. AEFI seriousness, demographic data, frequency and vaccine data were analysed. Results 3,200 neurological events were reported to the MoH during the period and 2,885 were consistent with AEFI (52.1% male). Three deaths were reported and 1.32% presented some sequel. Among all the vaccines that are part of the Brazilian calendar, the most frequent neurological AEFI reported were febrile and afebrile seizures (67.83% and 21.21%, respectively) and the highest rates were observed after the Diphtheria, Tetanus, Pertussis, and Haemophilus influenzae type b combined vaccine (50.36%). Guillain Barre syndrome also was reported (1.4%). The Influenza vaccine was the most related with this AEFI (0.7 cases per 1,000,000 doses). Conclusion Brazil's National Immunization Program (NIP) is one of the most extensive (27 vaccines, 4 immunoglobulins and 13 sera), offered with no cost to all its population. In this period more than 550 million of vaccines' doses were administered. Although the Brazilian AEFI surveillance system is mostly passive (based in the received reports), and on the fact that AEFI data can be underestimated, this large series shows that the majority of the AEFI are not serious and rates are within the expected from the literature. It is necessary to stimulate reporting, adequate investigation and causality assessment for keeping the population's confidence in NIP.