Clinical Outcomes and Pharmacotherapy Effectiveness in the VA Health Care System (COPE-VA)

The purpose of this study is to comprehensively describe the temporal and geographic utilization of COVID-19 therapies used for mild to moderate disease during different periods of SARS-CoV-2 variant circulation as well as to compare demographic and clinical characteristics of Veterans who are treated or do not receive these different therapies. The investigators will also perform similar descriptive epidemiology for other respiratory viruses, including RSV and influenza and other infectious diseases. This first phase will critically inform feasibility and direction of the second phase, in which the investigators will use target trial emulation design to study the comparative effectiveness of therapies and vaccines for COVID-19, respiratory viruses, including RSV, and influenza, and other infectious diseases.

Inclusion Criteria: Phase 1: \- Veterans with a laboratory-confirmed positive test for SARS-CoV-2 or a diagnosis of COVID-19 documented at any time since the beginning of the pandemic in January 2020 to present Phase 2: * All Veterans alive and in Veterans Health Administration (VHA) care as of January 2018 * Specific exclusion/inclusion criteria and observation periods will be further defined for each sub-study (See outcomes/publications) Exclusion Criteria: * VA employees who are not enrollees