South Korea is considering deploying only vaccinated service members on overseas missions, the defense ministry said Monday, following a mass COVID-19 outbreak at the anti-piracy Cheonghae unit in waters off Africa that infected 90 percent of its members.

According to a report submitted to the parliament's defense committee, the ministry's legal affairs bureau is reviewing adding COVID-19 vaccination as a requirement for overseas deployment.

Last week, all 301 members of the Cheonghae unit's 34th contingent were airlifted home after 247 service members tested positive for the new coronavirus. Subsequent tests found 25 more cases, raising the total caseload to 272 as of Sunday.

The military has come under fire for its poor initial response to the outbreak and for not actively seeking ways to inoculate the service members.

None of the sailors had been vaccinated, as they left South Korea in February, weeks before the country began the vaccination campaign.

According to the ministry, around 95 percent of some 1,010 troops on overseas missions have received at least one dose of COVID-19 vaccines, including most of the 35th batch of the Cheonghae unit, which left the country in June as a replacement.

"We will conduct regular virus tests on 56 unvaccinated members," the ministry said.

As of Sunday, 520,000, or 95 percent, of the military's 550,000 troops have received at least one dose of COVID-19 vaccines.

The second shots were given to 497,000 troops, with the military planning to wrap up the two-dose inoculation by next month. (Yonhap)