Comparison of infection control strategies to reduce COVID-19 outbreaks in homeless shelters in the United States: a simulation study

BMC Medicine

Margot Kushel¹  Caroline Cawley²  Bryan Greenhouse³  Lloyd A. C. Chapman³  Nathan C. Lo³  Isabel Rodriguez-Barraquer³  Elizabeth Imbert⁴  Ashley Scarborough⁵  Sarah N. Cox⁵  Trang Q. Nguyen⁵ 

[1] Center for Vulnerable Populations, Zuckerberg San Francisco General Hospital and Trauma Center, University of California, San Francisco, San Francisco, CA, USA;Department of Emergency Medicine, University of California, San Francisco, San Francisco, CA, USA;Department of Medicine, University of California, San Francisco, 94110, San Francisco, CA, USA;Division of HIV, Infectious Diseases, and Global Medicine, University of California, San Francisco, San Francisco, CA, USA;San Francisco Department of Public Health, San Francisco, CA, USA;

关键词: COVID-19;    SARS-CoV-2;    Homelessness;    Shelters;    Infection control;    Outbreaks;    Symptom-based screening;    PCR testing;    Universal masking;   

DOI  :  10.1186/s12916-021-01965-y

来源: Springer

【 摘 要 】

BackgroundCOVID-19 outbreaks have occurred in homeless shelters across the US, highlighting an urgent need to identify the most effective infection control strategy to prevent future outbreaks.MethodsWe developed a microsimulation model of SARS-CoV-2 transmission in a homeless shelter and calibrated it to data from cross-sectional polymerase chain reaction (PCR) surveys conducted during COVID-19 outbreaks in five homeless shelters in three US cities from March 28 to April 10, 2020. We estimated the probability of averting a COVID-19 outbreak when an exposed individual is introduced into a representative homeless shelter of 250 residents and 50 staff over 30 days under different infection control strategies, including daily symptom-based screening, twice-weekly PCR testing, and universal mask wearing.ResultsThe proportion of PCR-positive residents and staff at the shelters with observed outbreaks ranged from 2.6 to 51.6%, which translated to the basic reproduction number (R0) estimates of 2.9–6.2. With moderate community incidence (~ 30 confirmed cases/1,000,000 people/day), the estimated probabilities of averting an outbreak in a low-risk (R0 = 1.5), moderate-risk (R0 = 2.9), and high-risk (R0 = 6.2) shelter were respectively 0.35, 0.13, and 0.04 for daily symptom-based screening; 0.53, 0.20, and 0.09 for twice-weekly PCR testing; 0.62, 0.27, and 0.08 for universal masking; and 0.74, 0.42, and 0.19 for these strategies in combination. The probability of averting an outbreak diminished with higher transmissibility (R0) within the simulated shelter and increasing incidence in the local community.ConclusionsIn high-risk homeless shelter environments and locations with high community incidence of COVID-19, even intensive infection control strategies (incorporating daily symptom screening, frequent PCR testing, and universal mask wearing) are unlikely to prevent outbreaks, suggesting a need for non-congregate housing arrangements for people experiencing homelessness. In lower-risk environments, combined interventions should be employed to reduce outbreak risk.

【 授权许可】

CC BY