Incident COVID-19 Infections, Active and Reserve Components, 1 January 2020-31 August 2021.

Between 1 January 2020 and 31 August 2021, a total of 189,239 service members were identified as confirmed or probable cases of COVID-19. The majority of cases were male (81.2%) and 57.3% were aged 20-29 years. Overall, 19.2% had a diagnosis of at least 1 of the pre-existing comorbidities of interest in the year prior to becoming a case. The most common pre-existing comorbidity was obesity or overweight (5.2%), followed by cardiovascular disease (4.2%), and substance use disorder including nicotine dependence (4.0%). Service members who were hospitalized for COVID-19 were twice as likely to have a diagnosis of any pre-existing comorbidity compared to those who were not hospitalized. There were a total of 1,760 hospitalizations (0.9%) and 45 deaths reported among service members. In addition, there were 11,899 cases observed among fully vaccinated individuals; however, only 0.4% of hospitalized cases were fully vaccinated and no service member deaths occurred among fully vaccinated individuals during the surveillance period, highlighting the importance of COVID-19 vaccination for force health protection.