Investigating the Mental Health Burden of the COVID-19 Pandemic in Two Populations from Different Socioeconomic Levels in São Paulo, Brazil: A Qualitative Analysis. Principles and Practice of Clinical Research, [S. l.], v. 11, n. 2, 2025. DOI: 10.21801/ppcrj.2025.112.2. Disponível em: https://journal.ppcr.org/index.php/ppcrjournal/article/view/335.. Acesso em: 7 nov. 2025.