South Korea has reported 19 new cases of the coronavirus, most from the densely populated Seoul metropolitan area, where officials have been actively tracing transmissions linked to nightclubs and other entertainment venues.

South Korea’s Centers for Disease Control and Prevention on Tuesday also reported two more deaths, bringing national totals to 11,225 and 269 fatalities. Officials linked three of the new cases to international arrivals.

South Korea has been reporting around 20 new cases per day over the past two weeks after health workers found hundreds of infections linked to clubgoers who went out in early May as the country eased on social distancing.

People wearing face masks walk near a banner showing precautions against the new coronavirus at a bus stop in Seoul, South Korea, Monday, May 25, 2020. South Koreans will be required to wear masks when using public transportation and taxis nationwide starting Tuesday as health authorities look for more ways to slow the spread of the coronavirus as people increase their public activities. (AP PhotoLee Jin-man)

People wearing face masks walk near a banner showing precautions against the new coronavirus at a bus stop in Seoul, South Korea, Monday, May 25, 2020. South Koreans will be required to wear masks when using public transportation and taxis nationwide starting Tuesday as health authorities look for more ways to slow the spread of the coronavirus as people increase their public activities. (AP PhotoLee Jin-man)

The caseload has slowed from early March when it was reporting hundreds of new cases a day, but the new infections in the greater capital area has caused concern as authorities proceed with a phased reopening of schools, which began with high school seniors last week.

Around 2.4 million high school juniors, middle school seniors, first- and second-grade elementary school children and kindergartners will be returning to school on Wednesday.

Health Minister Park Neung-hoo during a virus meeting urged school officials to double-check their preventive measures. He called for authorities to strengthen monitoring on some 390,000 undocumented foreign nationals who may have poor access to medical services and tests, but related measures weren’t immediately announced.

A security official wearing protective face mask stands guard before the second plenary session of China's National People's Congress (NPC) at the Great Hall of the People in Beijing, Monday, May 25, 2020. (Roman PilipeyPool Photo via AP)

A security official wearing protective face mask stands guard before the second plenary session of China's National People's Congress (NPC) at the Great Hall of the People in Beijing, Monday, May 25, 2020. (Roman PilipeyPool Photo via AP)

In other developments in the Asia-Pacific region:

— VACCINE TRIAL BEGINS: U.S. biotechnology company Novavax began injecting a coronavirus vaccine candidate into people in Australia with hopes of releasing a proven vaccine this year. The first phase of the vaccine trial involves 131 volunteers and will test the safety of the vaccine while looking for signs of its effectiveness. About a dozen experimental vaccines are in early stages of testing or poised to start. It’s not clear that any will prove safe and effective. Novovax expects the results of the Australian trial to be known in July and it’s making more doses in anticipation the vaccine will work.

— SEVEN CASES IN CHINA: China reported seven new virus cases, all tied to Chinese returning from abroad. Just 81 patients remain hospitalized in the country with COVID-19, and another 408 are in isolation and being monitored for being either suspected cases or having tested positive for the virus without showing any symptoms. China has recorded 4,634 deaths from the disease among 82,992 cases. With the decline in numbers, students have gradually returned to class and some international schools in the capital Beijing are preparing to reopen on June 1. China's ceremonial parliament is meeting this week, with social distancing and other anti-virus measures being used.

Attendants wearing protective face masks fill up glasses for delegates before the second plenary session of China's National People's Congress (NPC) at the Great Hall of the People, in Beijing, Monday, May 25, 2020. (Roman PilipeyPool Photo via AP)

Attendants wearing protective face masks fill up glasses for delegates before the second plenary session of China's National People's Congress (NPC) at the Great Hall of the People, in Beijing, Monday, May 25, 2020. (Roman PilipeyPool Photo via AP)

Security officials wearing protective face masks sit guard before the second plenary session of China's National People's Congress (NPC) at the Great Hall of the People in Beijing, Monday, May 25, 2020. (Roman PilipeyPool Photo via AP)

Security officials wearing protective face masks sit guard before the second plenary session of China's National People's Congress (NPC) at the Great Hall of the People in Beijing, Monday, May 25, 2020. (Roman PilipeyPool Photo via AP)