Positive impact of facility-based isolation of mild COVID-19 cases on effectively curbing the pandemic: a mathematical modelling study

Chen, Simiao; Chen, Qiushi; Yang, Juntao; Lin, Lin; Li, Linye; Jiao, Lirui; Geldsetzer, Pascal; Wang, Chen; Wilder-Smith, Annelies; Bärnighausen, Till

BACKGROUND: In many countries, patients with mild coronavirus disease 2019 (COVID-19) are told to self-isolate at home, but imperfect compliance and shared living space with uninfected people limit the effectiveness of home-based isolation. We aim to examine the impact of facility-based isolation compared to self-isolation at home on the continuing epidemic in the United States. METHODS: We developed a compartment model to simulate the dynamic transmission of COVID-19 and calibrated it to key epidemic measures in the United States from March to September. We simulated facility-based isolation strategies with various capacities and starting times under different diagnosis rates. The primary model outcomes included the reduction of new infections and deaths over two months from October onwards. We further explored different effects of facility-based isolation under different epidemic burdens by major US Census Regions, and performed sensitivity analyses by varying key model assumptions and parameters. RESULTS: We projected that facility-based isolation with moderate capacity of 5 beds per 10 000 total population could avert 4.17 (95% Credible Interval 1.65–7.11) million new infections and 16 000 (8000-23 000) deaths in two months compared with home-based isolation, equivalent to relative reductions of 57% (44–61%) in new infections and 37% (27–40%) in deaths. Facility-based isolation with high capacity of 10 beds per 10 000 population would achieve greater reduction of 76% (62–84%) in new infections and 52% (37–64%) in deaths when supported by the expanded testing with a 20% daily diagnosis rate. Delays in implementation would substantially reduce the impact of facility-based isolation. The effective capacity and the impact of facility-based isolation varied by epidemic stage across regions. CONCLUSION: Timely facility-based isolation for mild COVID-19 cases could substantially reduce the number of new infections and effectively curb the continuing epidemic compared to home-based isolation. The local epidemic burden should determine the effective scale of facility-based isolation strategies.