- On 2 Oct, 46 cases amongst soldiers at an Army unit located in the border county of Yeoncheon has been reported. Of the cases, 41 (89%) were vaccine breakthrough infections and most of the confirmed patients were not showing any symptoms.
- Between 5- 6 Oct, six cases including Joint Chiefs of Staff (JCS) officer and five Army soldiers was reported on 5 Oct. Eight cases among service members and one case in a civilian worker for the military has been reported on 6 Oct and all of them were fully vaccinated.
- On 7 Oct, twelve cases among service members and two cases among civilian workers for the military have been reported, of which nine were breakthrough infections, raising the total number of breakthrough cases to 248.
- On 8 Oct, twenty-two draftees at an Army boot camp just south of the inter-Korean border were reported positive for COVID-19 of whom only three had received their first dose of vaccine. Additionally, the defense ministry reported the first COVID-19 case from its headquarters in central Seoul. Another seven cases were reported by the military at other bases including three new enlistees at an Army boot camp in Busan and four soldiers, bringing the total caseload in the military to 1,896.
[6-7] United States Forces Korea
- On 1 Oct, the USFK reported 11 cases among American service members and six cases among individuals affiliated with the USFK. The service members were either from Camp Humphreys in Pyeongtaek, Camp Casey in Dongducheon, or the Osan, Suwon, and Seongnam air bases while two individuals were South Korean workers for the U.S. military and four family members.
- On 7 Oct, the USFK reported 13 cases among people affiliated with USFK, including six service members. The latest cases raised the total number of infections reported among the USFK-affiliated population to 1,471.
 United States Forces Japan
- On 1 Oct, the US military bases in Japan reported 13 new cases of which 2 cases were from Yokosuka Naval Base and 11 cases from Kadena Air Base on Okinawa.
[9-10] United States
- On 4 Oct, death of a 51-year-old Navy petty officer due to coronavirus complications was announced making it the 14th such Navy fatality. The officer tested positive for COVID-19 on Sept. 17 however, his vaccination status has not been revealed. say whether he was among the 90% of its active-duty force that had been fully vaccinated.
- As of 6 Oct, a total of 246,720 cases with 2,246 hospitalizations and 62 deaths have been reported in the US military. There were 86,107 cases in the Army, 47,988 cases in the Navy, 42,590 cases in the Air Force, 40,139 cases in the National Guard, 28,326 cases in the Marine Corps and 1,570 cases in the DoD Agencies.