1 Department of Social Medicine, Federal University of Pernambuco, Recife, Brazil; Department of Community Health, Federal University of Pernambuco, Vitória de Santo Antão, Brazil. Electronic address: thalia@ufpe.br.
2 Department of Community Health, Federal University of Goiás, Goiânia, Brazil.
3 The Research Center Aggeu Magalhães (CPqAM) and Oswaldo Cruz Foundation (Fiocruz), Recife, Brazil.
4 Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK.