The emergence of vaccine hesitancy among upper-class Brazilians: Results from four birth cohorts, 1982-2015.

Vaccine hesitancy has been increasingly reported in Brazil. We describe secular trends and socioeconomic disparities from 1982 to 2015, using data from four population-based birth cohorts carried out in the city of Pelotas. Full immunization coverage (FIC) was defined as having received four basic vaccines (one dose of BCG and measles, and three doses of polio and DTP) scheduled for the first year of life. Information on income was collected through standardized questionnaires, and the slope index of inequality (SII) was calculated to express the difference in percent points between the rich and poor extremes of the income distribution. Full immunization coverage was 80.9% (95% CI 79.8%; 82.0%) in 1982, 97.2% (96.1%; 98.0%) in 1993, 87.8% (86.7%; 88.8%) in 2004 and 77.2% (75.8%; 78.4%) in 2015. In 1982 there was a strong social gradient with higher coverage among children from wealthy families (SII = 25.0, P < 0.001); by 2015, the pattern was inverted with higher coverage among poor children (SII = -6.0; P = 0.01). Vertical immunization programs in the 1980s and creation of the National Health Services in 1980 eliminated the social gradient that had been present up to the 1980s, to reach near universal coverage. The recent decline in coverage is likely associated with the growing complexity of the vaccination schedule and underfunding of the health sector. In addition, the faster decline observed among children from wealthy families is probably due to vaccine hesitancy.