(ATTN: UPDATES with latest tally in para 6; ADDS more details in paras 23-24)
SEOUL, Sept. 22 (Yonhap) -- South Korea's daily coronavirus cases stayed in the 1,700s for the second consecutive day on Wednesday despite fewer tests during an extended Chuseok holiday, raising concerns over a spike in new infections across the nation after the holiday.
The country reported 1,720 new COVID-19 cases, including 1,703 local infections, raising the total caseload to 290,983, according to the Korea Disease Control and Prevention Agency (KDCA).
The latest caseload was slightly down from 1,729 on Tuesday, but it was seen as mainly attributable to fewer tests over the fall harvest Chuseok holiday, which runs from Monday to Wednesday.
Daily cases have stayed over 1,000 for the last 78 days amid the fast spread of the more transmissible delta variant nationwide.
The country added six more deaths from COVID-19 on the day, raising the death toll to 2,419.
Health authorities and local governments reported 1,321 new cases as of 6 p.m., up 228 from the same time the previous day.
The Seoul metropolitan area, home to half of the nation's 52 million population, has emerged as the hotbed of the country's latest wave of the pandemic, accounting for 77 percent of the total.
The KDCA said 40 percent of them are untraceable cases, warning of more "silent transmissions" by people who have been infected with the virus but have not shown symptoms after the Chuseok holiday.
"The virus is still in full swing in the Seoul metropolitan area, and the transmission rate is rising among students following the school reopening," the KDCA said. "The virus could spread across the nation due to the increased traffic and more private gatherings during the Chuseok holiday."
Health officials urged people to get preemptive COVID-19 tests after the extended holiday to prevent further infections.
"The virus situation in the non-capital area could worsen due to the increased traffic during the holiday," Kang Do-tae, Vice Minister of Health and Welfare, said in a virus response meeting. "It is important for people to actively get preemptive testing."
The number of locally transmitted cases reached 1,798 over the past week, up 4.3 percent from a week earlier.
Nine out of 10 patients have not yet received their vaccine jabs or are partially inoculated, with those in their 20s and 30s showing a higher ratio than other age groups, the KDCA said.
The reproduction rate, which refers to the number of people a single patient can infect, was 1.03 over the last seven days, moving upward from 1.01 the previous week.
The nation confirmed 3,313 new COVID-19 variant cases from Sept. 12-18, mostly the delta variant, raising the total to 29,987.
There have been 5,880 breakthrough cases among 14.6 million people who were fully vaccinated as of Sept. 12, accounting for roughly 0.04 percent. Those in their 30s had the highest rate of breakthrough infections.
Earlier this month, the government extended the highest social distancing rules of Level 4 of its four-tier system for Seoul and the surrounding Gyeonggi Province and Level 3 for other regions until Oct. 3, limiting the size of private gatherings and restaurant business hours.
But it eased some restrictions, allowing family gatherings of up to eight people on the condition that four of them are fully vaccinated.
Instead, it has been enforcing special quarantine steps, such as running makeshift test centers at major bus terminals and train stations to detect patients at an early stage.
A total of 36.5 million people, or 71.2 percent of the country's population, have received their first shots of COVID-19 vaccines, and 22.2 million people, or 43.2 percent, have been fully vaccinated, the KDCA said.
The first-shot vaccination rate of 70 percent was achieved before the Chuseok holiday, as the country has accelerated its vaccination drive.
The government said that an airplane carrying 4.62 million doses of Pfizer's vaccine arrived at Incheon International Airport earlier in the day.
Health authorities are in talks with Pfizer to buy additional doses of COVID-19 vaccines for next year other than the 30 million shots that it has bought, the KDCA said.
The country signed a deal with Pfizer in August to buy 30 million doses of COVID-19 vaccines and has an option to purchase an additional 30 million doses when needed.
Of the newly confirmed domestic cases, 641 cases came from Seoul, 528 from the surrounding Gyeonggi Province and 145 cases from the western port city of Incheon.
Imported cases, which include South Korean nationals, came to 17.
The number of patients with serious symptoms across the country reached 317, down 11 from the previous day.
The total number of people released from quarantine after making full recoveries was 261,812, up 1,722 from a day earlier.