Health promotion in Brazil relies on community health workers (CHWs), frontline providers linking the health system and vulnerable groups. Brazilian CHWs are overwhelmingly women from poor backgrounds, with precarious and sometimes hazardous working conditions, as well as fragmented and unsystematic training. This paper evaluates how the COVID-19 pandemic exacerbated pre-existing vulnerabilities of CHWs (pertaining to low salary, precarious and hazardous working conditions and inadequate training) and created new ones, with a profound impact on their ability to carry out health promotion activities. Drawing on testimonials of dozens of CHWs and online discussions promoted by their unions, the paper reveals that during the pandemic CHWs were asked to continue their work without adequate training and protective equipment, thus exposing themselves to the risk of infection. It further shows how the pandemic rendered dangerous the close interaction with patients that is at the heart of their health promotion role. Nonetheless, CHWs sought to adapt their work. In the absence of leadership and coordination on the part of the federal government, CHWs mobilized different forms of resistance at the national and individual levels. Notwithstanding this, COVID-19 contributed to a trajectory of erosion of health promotion in Brazil. Findings from this case signal the difficulties for health promotion in low- and middle-income countries relying on CHWs to bridge the health system and vulnerable users.