Volatility of the COVID-19 vaccine hesitancy: sentiment analysis conducted in Brazil - Machado Júnior, Celso; Mantovani, Daielly Melina Nassif; de Sandes-Guimarães, Luísa Veras; Romeiro, Maria do Carmo; Furlaneto, Cristiane Jaciara; Bazanini, Roberto (Frontiers in Public Health - Front, 2023)