key: cord-0767668-zvjgv4ol authors: Ly, Tran Duc Anh; Nguyen, Nhu Ngoc; Hoang, Van Thuan; Goumballa, Ndiaw; Louni, Meriem; Canard, Naomie; Dao, Thi Loi; Medkour, Hacene; Borg, Audrey; Bardy, Kevin; Esteves-Vieira, Véra; Filosa, Véronique; Davoust, Bernard; Mediannikov, Oleg; Fournier, Pierre-Edouard; Raoult, Didier; Gautret, Philippe title: Screening of SARS-CoV-2 among homeless people, asylum-seekers and other people living in precarious conditions in Marseille, France, March–April 2020 date: 2021-02-10 journal: Int J Infect Dis DOI: 10.1016/j.ijid.2021.02.026 sha: a1cbdc0d78a566c08449ec398f8c9125f0aaede0 doc_id: 767668 cord_uid: zvjgv4ol 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. potentially be exposed to this infection and have potentially more severe outcomes than in the general population, due to their poor living conditions, the higher prevalence of comorbidity, and mental and physical conditions impaired by substance or alcohol abuse (Lima et al., 2020; Tsai and Wilson, 2020; Kirby, 2020; Kar et al., 2020; Neto et al., 2020) Crowded conditions in shelters without specific preventive measures could facilitate viral transmission (Peate, 2020; Wood et al., 2020) . In an early study conducted between March-April in Hamilton, Canada, 1% of sheltered homeless persons and 5% of staff-members were diagnosed with COVID-19 (Bodkin et al., 2020) . In several U.S. cities, in the same period, 1192 residents and 313 staff members were tested in 19 homeless shelters and high rates of SARS-CoV-2 carriage were observed in residents (25%) and staff members (11%) (Baggett et al., 2020a; Mosites et al., 2020) ; the prevalence was also reported to be 9.7-15.5% and 13.3%-14.8% among residents and staff members in three homeless shelters in Washington, respectively (Tobolowsky et al., 2020) , and 67.3%-16.7% among residents and staff members in one homeless shelters in San Francisco, respectively (Imbert et al., 2020) . In addition, 2.0% residents from 14 shelters tested positive in Washington (Rogers et al., 2020) , 11.9% residents from fives shelters in Rhode Island (Karb et al., 2020) , 2.1% residents from 24 shelters in Atlanta (Yoon et al., 2020) , and 33.1% of sheltered homeless and marginally housed people in Boston (Baggett et al., 2020b) . This raised concerns that the virus may be widely transmitted within homeless shelters. Over the past two decades, our institute has carried out a large number of surveys among homeless persons within two shelters (A and B) in Marseille, France. We observed a high prevalence of respiratory symptoms and signs (Badiaga et al., 2009 ) and high carriage rates of both respiratory viruses (Thiberville et al., 2014) and bacteria (Ly et al., 2019) , suggesting that SARS-CoV-2 infection might also be frequent in this population. Based on the preliminary information that some homeless persons from these two shelters presented with COVID-19 symptoms, we organised a screening campaign in collaboration with the staff in charge of these shelters. We subsequently received other requests for screening from several accommodation centres specialising in housing vulnerable people. In this study, we present the results of SARS-CoV-2 screening campaigns conducted among sheltered homeless individuals, in comparison with J o u r n a l P r e -p r o o f asylum-seekers, other persons living in precarious conditions, and employees working in the accommodation centres. We also investigated the role of potential risk factors for virus carriage among the homeless population. 2.1. Ethics Ethical approval was obtained from the Institutional Review Board and Ethics Committee of our institute (2020-015). A cross-sectional survey was conducted between 26 March and 17 April 2020 in different populations including homeless people residing in four shelters (A-D) and four hotels that were specifically recruited to house homeless people during the pandemic (1-4), other people living in precarious condition (housed in residences α and β), asylum-seekers (housed in residence γ), and employees working in these accommodation centres. This represents a convenience sample because these residences requested testing. Follow-up was conducted in three shelters (A-C) until November 2020. Homeless shelters (A-C) include emergency (overnight stay) units with a rapid turnover (7-14 nights), and special (permanent stay) units dedicated to high-risk sedentary homeless persons characterised by a high level of poverty, poor hygiene, alcoholism, mental illness and chronic diseases. Shelters A and B are for men only while shelter C is for women only. Shelter D houses male and female homeless people and offers the possibility to keep their pets when needed. Characteristics of the facilities are described in Table 1 . All residents of homeless shelters were placed under strict lockdown since 17 March, in line with the whole French population (=C0), requiring all homeless people to stay in the shelter 24 hours a day. Homeless persons were required not to leave shelters for any reason (with rare exceptions). The residences provided all necessary items. A few individuals were newly admitted and all were tested for SARS-CoV-2 and isolated before results were available. The male population of Shelter A (initial group A) was sub-divided into three groups by the staff of the facility, in order to avoid overcrowding: i) elderly people, those with reduced mobility and those needing medical care were kept in Shelter A, ii) people J o u r n a l P r e -p r o o f aged 18-45 were progressively moved to Hotel 1 from C0 to C7, iii) people aged 30-80 years were moved to Hotel 2 from C7 to C14. Similarly, the female population of Shelter C (initial group C) was sub-divided into three groups: elderly people, those with reduced mobility and those needing medical care were kept in Shelter C, ii) pregnant women and those with mental illness were moved to Hotel 3 at C0; iii) others were moved to Hotel 4 at C0. All residents moved to hotels have been kept under relatively strict lockdown since C0, with the exception of the day of transfer. Residence α is dedicated to individuals characterised by a high level of poverty, poor hygiene, alcoholism, mental illness and chronic diseases including drug addiction. Residence β specialises in housing teenage mothers and their children. Residence γ is dedicated to asylum-seekers, including family groups and single individuals. All three residences offer long-time housing and all residents have been kept under strict lockdown since C0. These residences were located in different part of Marseille, far from each other. Employees of the different facilities working in different sectors (management staff, social workers, nurses, cleaning staff, catering staff and security staff) returned to their homes on a daily basis after finishing work. Employees did not work in multiple facilities with the exception of medical staff in shelter A and C who cared people in hotels 1-2 and 3-4, respectively. Participants were encouraged by the management staff of the facilities to get tested and were then recruited on a voluntary basis. They were systematically asked to provide basic demographic information (sex, age, country of origin), chronic conditions, and any respiratory symptoms or fever in the two weeks prior to sampling. Body temperature was measured using a forehead infrared thermometer. We defined a fever as temperature measured ≥37.8 C. Nasal samples were systematically collected on transport media using Sigma Transwabs (Medical Wire, Corsham, United Kingdom). For self-sampling, participants were invited to insert the swab into their nostrils (about 2 cm). If individuals were unable to perform selfsampling, trained investigators carried out the sampling. Specimens were immediately processed for J o u r n a l P r e -p r o o f SARS-CoV-2 PCR testing. Homeless peoples' pets were also tested with the approval of their owner and their nasal swabs were collected by vets. The test result was informed to participants or medical staffs in a delay of 24 hours. Before testing, residents were informed about what would happen if test result was positive. Positive residents were moved to special facilities for COVID-19 homeless patient isolation or kept in single room at residences with strict isolation measures for 14 days. Infected staffs were instructed to stay at home for 14 days. Real-time reverse transcription-PCR amplification was used to confirm the presence of SARS-CoV-2 RNA targeting the gene coding for the envelope (E) protein, as previously described (Amrane et al, 2020). Results were considered positive when the cycle threshold (CT) value of real-time PCR was ≤35. Statistical procedures were performed using STATA 11.1 software (StataCorp LLC, USA). Percentage differences were tested using Pearson's chi-square or Fisher's exact tests when appropriate. Means of quantitative data were compared using Student's t-test. A p value <0.05 was considered statistically significant. A separate multivariate logistical regression analysis was used to identify independent risk factors for SARS-CoV-2 carriage prevalence among all individuals and in selected groups (when positive cases were found). The results were presented by percentages and odd ratio (OR) with 95% confidence interval (95%CI). The initial model included variables presenting a p-value <0.2. The stepwise regression procedure and likelihood-ratio tests were applied to determine the final model. Overall, 885 individuals were present in the various facilities at the time of enrolment, including 716 residents and 169 employees ( J o u r n a l P r e -p r o o f asylum-seekers (11.0%), and 152 employees (21.8%). Overall, 38.7% were enrolled before C14, 45.9% between C14 and C20, and 15.4% at C21 and later. The overall acceptation rate of SARS-CoV-2 testing varied significantly according to the housing facility, ranging from 41.7 to 91.7%. The overall acceptation rate among homeless individuals was 74.6% and was significantly lower than that of employees working in the homeless centres (88.7%, p=<0.001) ( Table 2 ). The acceptance rate among people housed in other facilities, varied from 75.5 to 100% and tented to be lower than that of employees in these facilities ( Table 2 ). The socio-demographic characteristics of the different populations are presented in Table 3 . The male to female gender ratio was 3:1 and the median age was 35.0 years (ranging from 0 to 91 years) with significant variations among different populations. A male predominance was observed among homeless persons and asylum seekers. Children ≤15 years old accounted for 7.5% of all residents. Twothirds of individuals were migrants. A predominance of African origin was found among homeless individuals, while other people living in precarious conditions and employees were more likely to be European. Most asylum seekers were from African and Asian origin. There were only four pregnant women (between 26 and 36 weeks of pregnancy), all housed in Hotel 3. Regarding clinical findings, among all the participants, 22.1% reported at least one respiratory symptom or fever with significant variations among different populations. The highest prevalence was observed among employees (25.7%) and homeless persons (24.3%). A cough was the most commonly reported symptom (32.7%) followed by rhinorrhoea (20.4%), dyspnoea (12.2%) and fever (12.2%). No deaths were reported during the study period. In total, 49 participants (7.0%) tested positive for SARS-CoV-2, including 37 homeless people (of 441, 9.0%) and 12 employees (of 152, 7.9%, including seven security staff from Shelters A, B and C and residence γ, four nurses from Shelter B and one management staff member from Shelter C). Only two female homeless people tested positive, including one woman who was 36 weeks pregnant and who J o u r n a l P r e -p r o o f frequently attended the hospital during the lockdown and one person living at hotel 3 with mental illness who did not comply with lockdown measures, escaping frequently from the hotel. Two dogs belonging to two different homeless people in Shelter D tested negative. With regard to the housing facilities, the highest SARS-CoV-2 positivity rates were observed in homeless persons in Hotel 1 (39.1%), in Shelter A (18.5%) and in Hotel 2 (14.3%). Among employees, the highest positive rates were in those working at homeless Shelters B (14%) and A (12.5%). Of the 49 SARS-CoV-2-positive participants, 51.0% were asymptomatic. Positive participants were more likely to be symptomatic compared to negative participants (Odd-ratio OR=3.8 95%CI [2.1-6.9], p<0.001). There was no significant difference of PCR CT values between asymptomatic (mean CT [±SD]: 26.9±5.0) and symptomatic individuals (25.7±5.4, p=0.43). The overall proportion of asymptomatic carriers among all tested individuals was 3.6% and that of symptomatic carriers was 3.4%. Table 3 shows SARS-CoV-2 positivity rates among homeless people according to the time of screening, demographics and housing facility, using univariate analysis. No significant differences were observed according to gender and country of origin regarding SARS-CoV-2 positivity rates. Screening between C14 and C20 and screening in the group A population (Shelter A and hotels to which people from Shelter A were moved) resulted in a significantly higher proportion of positive PCR as compared to screening before C14 or screening in other homeless facilities, respectively. In addition, being young (18-34 years) was associated with an increased prevalence of virus detection. Cough, rhinorrhoea and fever were associated with viral carriage. Using multivariate analysis (Table 4) Measures to mitigate the risk of transmission included staying at housing facility, avoiding gathering of persons (including by moving individuals from shelters to hotels), wearing mask, keeping distance J o u r n a l P r e -p r o o f from others, washing hands with soap and water frequently and for at least 20 seconds, practicing cough etiquette, and avoiding touching the eyes, nose, or mouth with unwashed hands. Follow-up conducted in shelter A, B and C resulted in a strong decrease of PCR positivity rates with 1.1% and 0.4% residents of shelter A and B respectively testing positive in September and November while no resident of shelter C tested positive in October. To our knowledge, this is the only study addressing SARS-CoV-2 carriage among different precarious populations including homeless adults but also children and other hard-to-reach populations during the COVID-19 outbreak in France. In Marseille, the first case of COVID-19 in the general population was We found an overall 7.0% SARS-CoV-2 positivity rate, with most infected individuals among homeless people and employees working in homeless facilities, while no cases were found in asylum-seekers and in other people also living in precarious conditions. Detection of SARS-CoV-2 correlated with symptoms although many patients who tested positive did not report any respiratory symptoms or fever at the time of sampling. It cannot be excluded that some of them were actually pre-symptomatic. The high rate of asymptomatic SARS-CoV-2 carriers is in line with other studies conducted in homeless shelters in the US (Baggett et al., 2020a; Rogers et al., 2020; Karb et al., 2020) . Asymptomatic and presymptomatic transmission may therefore be the predominant SARS-CoV-2 transmission mode in shelters. As a consequence, symptom-guided screening in this setting does not represent an effective J o u r n a l P r e -p r o o f strategy. Given that homeless people and professionals in contact with homeless people are at a high risk of COVID-19, these populations should benefit from screening campaigns and specific measures aiming at mitigating the risks of transmission of the disease including personal protective measures, within these populations and to the overall population should be implemented. Among the population of the four homeless shelters (A-D) that were screened, the highest prevalence was observed in populations initially housed at Shelter A. This may have resulted from the higher number of individuals per room at this shelter, as compared to other shelters, which may have encouraged transmission of the virus. Sleeping in shared dormitories and using shared bathrooms, toilets and kitchens make the implementation of social distancing measures in the context of homeless shelters particularly challenging. Being young (18-34 years) was an independent factor associated with SARS-CoV-2 detection in the homeless group, which may be due to a higher propensity of younger homeless people to develop social interactions within the shelters and hotels as compared to older people aged ≥50 years. Measures that were undertaken by shelter staffs to mitigate the risk of transmission were effective in reducing the numbers of cases among residents with only a slight increase of cases observed at shelter B during the second epidemic in Marseille. This work has some limitations. Our study population was not randomly and homogenously recruited. Participants' medical histories and use of individual preventive measures were not documented. Individuals were not asked about anosmia and ageusia. No information was available regarding possible interactions of populations at other facilities (soup kitchen, day shelters) before lockdown. Notwithstanding these limitations, our data provide a novel insight into the epidemiology of SARS-CoV-2 among different vulnerable urban populations. The survey also reveals the role of collective housing in relation to viral transmission within accommodation centres. No potential conflict of interest relevant to this letter was reported. We are grateful to our colleagues for their help for statistical analysis, collection of samples and technical assistance. 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