Benefit 1: A population-based covid-19 ascertainment

Hospital data records a useful population perspective of the pandemic. Covid-19 case data can be misleading due to selective testing and they are susceptible to ascertainment bias (i.e. people tested for the disease do not represent the entire population). Widespread testing has been challenging in the earlier stages of the pandemic with low coverage and selective testing. However, the further expansion of testing will neither yield a consistent nor representative sample of covid-19 patients across time, disease severity, and social demographic groups. That stated, a high capacity for rapid testing is warranted because the diagnosis of confirmed cases is invaluable for early outbreak detection, outbreak detection in specific populations (e.g. long-term care homes), control using contact follow-up, and management of patients using isolation precautions. Serology testing will have a complementary role to inform how many people have had covid-19. Still, serology testing does not describe current outbreak dynamics, and it is expensive with logistical challenges to create a population perspective.
In a universal health care system, most covid-19 patients who require intensive treatment will likely be admitted to a hospital. This means that routinely-collected hospital patient data reflect a population the perspective of severe covid-19 infection that can be used to describe covid-19 transmission in both populations at high risk of complications and the overall community.
The recent divergence in the trend of new covid-19 cases and hospital census in several countries is instructive. In Canada, several provinces and cities report hospital and intensive care census (Fig. \ref{291967}). During March and early April, there was a rapid increase in hospitalization that coincided with a corresponding rapid increase in confirmed covid-19 cases. However, since then hospital census rates dropped more quickly than confirmed cases.