question: Background Surveillance of SARS-CoV-2 infection among sheltered homeless and other vulnerable people might provide the information needed to prevent its spread within accommodation centres. Methods Data was obtained from 698 participants in different accommodation centres (411 homeless individuals, 77 asylum-seekers, 58 other persons living in precarious conditions, and 152 employees working in these accommodation centres) who completed questionnaires and had nasal samples collected between 26 March and 17 April 2020. SARS-CoV-2 carriage was assessed by quantitative PCR. Results We found a high (78.9%) acceptance rate toward testing. Overall, 49 (7.0%) people were positive for SARS-CoV-2, including 37 homeless individuals (of 411, 9.0%), 12 employees (of 152, 7.9%). SARS-CoV-2 positivity correlated with symptoms, although 51% of positive patients did not report respiratory symptoms or fever. Among homeless people, being young (18-34 years) (OR: 3.83 [1.47–10.0], p = 0.006) and being housed in one specific shelter (OR: 9.13 [4.09–20.37], p < 0.001) were independent factors associated with the SARS-CoV-2 positivity rates (11.4% and 20.6%, respectively). Discussion Symptom screening alone is insufficient to prevent SARS-CoV-2 transmission in the vulnerable sheltered people. Systematic testing should be promoted.