Since the fall of 2020, researchers, stakeholders, and policymakers have, in the context of the pandemic, shared the latest knowledge and best practices with people experiencing homelessness to help them better protect themselves from COVID-19. This initiative, known as Knowledge Mobilization (MobCo), focuses on combating COVID-19 among people in vulnerable situations in France. This group, led by Santé publique France, provides a structured framework for sharing effective strategies to combat COVID-19 in France and abroad; it facilitates the development of partnerships, the exchange of experiences among stakeholders from different regions, and identifies promising avenues for action. In particular, it brought together 60 experts and field practitioners on testing in the fall of 2020, and 120 participants on vaccination in May 2021. MobCo is currently continuing its work.