A health worker prepares for a coronavirus test at a testing center in Seoul last Thursday. (Yonhap)

South Korea reported fewer than 20,000 COVID-19 cases Thursday as the rapid spread of the omicron variant is under control.

The country added 18,816 new infections, including 34 cases from overseas, bringing the total caseload to 18,036,720, the Korea Disease Control and Prevention Agency (KDCA) said.

The daily tally fell to a 17-week low for a Thursday and declined around 33 percent from a week earlier, as the virus curve has been trending downward since mid-March.

South Korea's daily caseload peaked at over 621,000 on March 17, driven by the rapid spread of the omicron variant nationwide.

The country added 34 deaths from COVID-19, taking the total to 24,063. The fatality rate stood at 0.13 percent. The number of critically ill patients stood at 243, the KDCA said.

South Korea is set to hold local elections and parliamentary by-elections next Wednesday to choose Seoul mayor and Gyeonggi Province governor, among others.

COVID-19 patients will be able to cast their ballot at the same polling stations as uninfected voters after the regular voting session is over.

The patients can vote between 6:30 p.m. and 7:30 p.m. on the election day and between 6:30 p.m. and 8 p.m. on the second day of early voting on Saturday at official polling stations, after getting temporary leave permits from health authorities.

Last month, the country rolled back most of its virus restrictions amid slowing infections, except for the seven-day self-isolation for COVID-19 patients, which remains in effect until June 20.

As part of efforts to ease COVID-19 entry rules, South Korea this week allowed international travelers to submit supervised rapid antigen test results, issued within 24 hours prior to their departure date, as well as PCR test results.

Of the locally transmitted cases, Seoul accounted for 2,787 cases, with its surrounding Gyeonggi Province reporting 4,350 cases. There were also 743 additional patients from Incheon, 40 kilometers west of the capital city.

As of midnight Wednesday, 44.57 million, or 86.9 percent of the population, had completed the full two-dose vaccinations, and 33.27 million, representing 64.8 percent, had received their first booster shots. More than 3.93 million people had gotten their second booster shots, the KDCA said. (Yonhap)