US Forces Korea (USFK) said Wednesday it is suspending the administration of the Johnson & Johnson (J&J) vaccine to its members following US health authorities' recommendation to pause its use amid concerns over blood clot cases.

"Following some rare instances of blood clotting in USA based individuals who recently received the Johnson and Johnson COVID-19 vaccine -- and out of an abundance of caution to protect the force based on a joint recommendation by the US FDA and CDC, and DOD directive -- USFK is immediately pausing the administration of the J&J vaccine," the US military said in a Facebook post.

The announcement came shortly after the US Food and Drug Administration and the Centers for Disease Control recommended a "pause" in use of the single-dose vaccine to look into blood clot cases reported in the country.

USFK advised its members who received the J&J vaccine to closely monitor their symptoms and immediately seek medical treatment if they experience severe headache, abdominal pain, leg pain or shortness of breath. It was not immediately clear how many doses of the vaccine have been administered to the US military population.

"At this time, the length of the pause is unknown but will be based on additional research conducted on the J&J vaccine," the US military said.

USFK has completed vaccinating nearly half of its population against the new coronavirus after launching the vaccination campaign with Moderna's in December.

As of last week, 821 coronavirus infections were reported among the USFK-affiliated population, most of whom tested positive upon their arrival here from the United States. (Yonhap)