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.

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We aimed to compare respiratory pathogen carriage by PCR during three different time periods in 2020 in sheltered homeless people in Marseille, France. The overall prevalence of respiratory pathogen carriage in late March–early April (69.9%) was significantly higher than in late April (42.3%) and mid-July (45.1%). Bacterial carriage significantly decreased between late March–early April and late April. SARS-CoV-2 was detected only in late March–early April samples (20.6%). Measures aiming at mitigating SARS-CoV-2 transmission were effective and also impacted bacterial carriage. Seasonal variations of bacterial carriage between winter and summer in this population were not marked. Supplementary Information The online version contains supplementary material available at 10.1007/s10096-020-04127-9.

Background: The Grand Magal of Touba is the largest Muslim pilgrimage in Senegal with a potential for infectious disease transmission. Methods: Clinical follow-up, adherence to preventive measures and qPCR-based respiratory and gastrointestinal pathogens carriage pre-and post-Magal, were assessed. Results: 110 pilgrims from South Senegal were included. The duration of stay in Touba was 3 days. 41.8% and 14.5% pilgrims reported respiratory and gastrointestinal symptoms. Most individuals having the onset of symptoms during their stay in Touba, or soon after returning. The acquisition of rhinoviruses, coronaviruses and adenovirus was 13.0, 16.7 and 4.6% respectively and that of Streptococcus pneumoniae and Haemophilus influenzae was 3.7% and 26.9%.Acquisition of gastrointestinal viruses and parasites was low, while bacterial acquisition ranged from 2.2% for Campylobacter jejuni to 33.0% for enteropathogenic Escherichia coli. Conclusion: This preliminary study confirms that Grand Magal pilgrims are likely to be exposed to communicable disease risk as observed in other pilgrimage settings. Further study including larger numbers of pilgrims are needed to investigate potential risk factors for respiratory and gastrointestinal infections at the Grand Magal.

150/150 words)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. In March-April, we enrolled 411 homeless individuals, 77 asylum-seekers, 58 people living in precarious conditions, and 152 employees working in these accommodation centres and collected nasal samples. SARS-CoV-2 carriage was assessed by quantitative PCR. 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 ], p<0.0001) were independent factors associated with the SARS-CoV-2 positivity rates (11.4% and 20.6%, respectively). The survey reveals the role of collective housing in relation to viral transmission within centres.