The U.S. Secretary of Health and Human Services declared a public health emergency in the U.S. on 31 January 2020 in response to the spread of coronavirus disease 2019 (COVID-19). On 20 March 2020, the President of the U.S. proclaimed that the COVID-19 outbreak in the U.S. constituted a national emergency, retroactive to 1 March 2020 . Between 1 January and 30 September 2020, a total of 53,048 Military Health System (MHS) beneficiaries were identified as confirmed or probable cases of COVID-19 infection . The majority of cases were male (69.1 %) and 45.4% were aged 20-29 years . The demographic and clinical characteristics of these cases varied by beneficiary type (active component service members, recruits, Reserve/Guard, dependents, retirees, and cadets). Of the total cases , 35.8% had been diagnosed with at least 1 of the comorbidities of interest, and 20.0% had been diagnosed with 2 or more comorbidities . The most common comorbidities present in COVID-19 cases were any cardiovascular diseases (12.7 %), obesity or overweight (11.1 %), metabolic diseases (10.5 %), hypertension (9.9 %), neoplasms (7.9 %), any lung diseases (7.5 %), substance use disorders, including nicotine dependence (5.4 %), and asthma (3.2 %). There were a total of 1,803 hospitalizations (3.4 %) and 84 deaths (0.2 %).