A service member of the Navy Submarine Command undergoes a temperature check prior to receiving a COVID-19 shot at a makeshift center in the southeastern city of Changwon, North Gyeongsang Province, last Wednesday, in this photo provided by the defense ministry. (Ministry of National Defense)

The defense ministry on Monday extended the current social distancing rules for the military for three weeks, which allow service members to take vacation in a limited manner.

The Level 2 scheme, which was supposed to expire Sunday, will be in place until May 23 in line with the government's COVID-19 guidance, according to the ministry. It is the third-highest level in the five-tier alert system.

Under the scheme, troops are allowed to go on vacation while strictly adhering to antivirus measures, such as a mandatory quarantine and coronavirus tests. Up to 20 percent of members of each base can go on leave at the same time.

But the stricter Level 2.5 social distancing has been in place in major Navy units since April 23 when 33 sailors who serve on the same naval ship tested positive. It was the first mass infection on a military vessel.

The Level 2.5 scheme, which bans troops' vacations and other off-installation trips, will continue through Friday, according to the Navy.

"We also designated this week as a special quarantine period at the barracks, which calls for canceling business trips, minimizing face-to-face meetings and expanding a flexible work system," a ministry official said.

Monday's decision came after the government extended the current Level 2 social distancing rules in the greater Seoul area and Level 1.5 for the rest of the country for another three weeks amid concerns of another wave of the pandemic.

On Monday, South Korea reported 488 more COVID-19 cases, including 465 local infections, raising the total caseload to 123,728, the Korea Disease Control and Prevention Agency (KDCA) said.

The military also reported two more virus cases among its members in the day -- an Army officer in the border town of Cheorwon and an airman in the eastern city of Wonju, bringing the total cases at the barracks to 791.

The defense ministry said it is working to speed up the vaccine inoculation campaign for service members.

Last week, the military began vaccinating troops aged 30 and older, and plans to administer shots to around 105,000 troops who volunteered for the campaign by next week, according to the ministry.

"We are discussing with health authorities vaccinating mission-critical troops in their 20s, including those working at guard posts in border towns, on submarines and major vessels as soon as possible," ministry spokesperson Boo Seung-chan told a regular briefing.

Some 45,000 troops aged 30 and younger are expected to receive either Pfizer or Moderna vaccines, and the campaign is scheduled to begin around June, officials said. (Yonhap)