The Importance of Long-term Care Populations in Models of COVID-19

In February 2020, the US outbreak of novel coronavirus disease 2019 (COVID-19) began with a cluster of cases at a long-term care (LTC) facility in Washington State. Since then, 34 of the 40 states with available data report that at least 40% of COVID-19-related deaths in those states have occurred in LTC facilities,1 which provide ideal conditions for rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although the populations in these facilities bear a significant burden of the pandemic, mathematical models that contribute to US national or state policy do not account for residents of LTC facilities separately from surrounding populations in their calculations.2 This Viewpoint explores why it is important to separate projections for residents of LTC facilities and the general population. Current major COVID models, including mechanistic ones like that from Imperial College London and hybrid forecasting ones like that from the Institute for Health Metrics and Evaluation, assume similar dynamics of SARS-CoV-2 transmission.3,4 Models like these calculate the number of susceptible, exposed, infectious, and recovered individuals (the standard SEIR