We are proposing to NIDA to provide a Competing Revision to an ongoing study to examine the relationship of substance use/substance use disorders (SU/SUD) to the risk for COVID-19 infection, and among those infected, progression to hospitalization, intensive care and either live hospital discharge or death. The population consists of veterans treated at the Veterans Administration, who are at high risk because they are largely male, older and have many chronic medical conditions that predict poor prognosis. The proposal responds to a NIDA NOSI requesting such additional to better understand the relationship of SU/SUD to COVID-19. Data on 5.7 million veterans will be derived from the Electronic Medical Record (EMR) system of the VA. This will be linked to Medicare data for greater information about patients age 65 and older, and to National Death Index data for underlying and contributing causes of death. The study leverages the research infrastructure created for the parent grant, and involves collaboration between experts at Columbia University and those with joint academic and VA links at other universities.