“Vaccine! Let’s vaccinate everyone!” rings out as doctors, nurses, and nongovernmental organization workers start a 17-day river trip in the Brazilian Amazon to reach artisanal fishers and harvesters. While communities have restricted visitors, illegal mining, logging, and land grabbing still bring in outsiders, spreading COVID with devastating consequences. The riverine people, who now have priority vaccination status, normally depend on poor municipalities for health care, in contrast to many Indigenous groups who have been vaccinated through a federally funded health department. The municipal health department of Altamira supplied the COVID-19 shots, local and US-based NGOs organized and funded this expedition, which cost nearly $20,000, and grassroots associations turned houses into improvised vaccination centers. In four trips between June and September, more than 700 of an estimated 1,700 people living on the Iriri, Xingu, and Riozinho do Anfrísio rivers were vaccinated.