The Brazilian National Immunization Program: 46 years of achievements and challenges.

The Brazilian National Immunization Program (PNI, in Portuguese) is coordinated by the Ministry of Health in cooperation with state and municipal health departments. Since the program's creation in 1973, it has become one of the country's most relevant public health interventions, having produced important results such as certification of Brazil as free of wild poliovirus circulation, the elimination rubella virus circulation, and an important reduction in cases and deaths from vaccine-preventable diseases. Brazil is one of the countries that offers the most vaccines free of cost to the population, with 15 vaccines for children, 9 for adolescents, and 5 for adults and the elderly. The program's expansion and the maintenance of high vaccination coverage rates led to a rapid decrease in vaccine-preventable diseases, completely changing the epidemiological scenario of these diseases in Brazil in the last four decades. The country is currently witnessing an increasing share of the population without adequate vaccination. To the extent that these diseases are no longer circulating, precisely because of the high vaccination coverage rates, especially since the early 2000s, many of them are now unknown to the population. As a result, many people have no notion of the danger these diseases represent. We thus need to understand the multiple factors contributing to this decrease in coverage, which has created the risk of resurgence of serious diseases that had already been controlled or eliminated in Brazil.