In Brazil, National Immunization Days (NIDs) are held twice a year to maintain the elimination of poliomyelitis and to provide routine immunization for children younger than five years of age. Few studies have examined factors associated with participation in National Immunization Days among Brazilian children, or the contribution of immunization days to the coverage of recommended vaccines. METHODS: We conducted a household cluster survey in 26 state capitals and the Federal District among children aged 19 to 35 months. Vaccination histories, including dates of vaccination, participation in the most recent NID or reasons for non-participation were obtained. Survey estimates were compared with official estimates based on doses administered. RESULTS: Among the 17,749 children surveyed, 16,213 (91%) participated in the most recent NID. Children who received vaccination in the private sector had the lowest participation (84%) in NIDs. In 13 capitals, official coverage estimates were higher than those from the survey. The main reasons given for non-participation the most recent NID included parent's decision not to participate, doctor's advice, child's illness, and factors associated with the organization of the NID. Overall, 15% of the children surveyed had received at least one immunization in addition to oral polio vaccine in the most recent NID, including yellow fever, hepatitis B, measles-mumps-rubella (MMR) and combined diphtheria-tetanus-pertussis-Haemophilus influenzae type b vaccines. CONCLUSIONS: In Brazilian capitals, National Immunization Days continue to enjoy high levels of acceptance by the population and offer opportunities to complete recommended immunization schedules. Reasons for non-participation suggest the need for different communication strategies to reach parents who do not bring their children for vaccination on NIDs.
Poliomyelitis; Healthcare surveys; Mass vaccination; Immunization programs
