South Korea's daily new coronavirus cases stayed in the 400s for the sixth day in a row Monday as cluster infections continued to pop up across the country, raising concerns over a resurgence during spring.

The country reported 415 more COVID-19 cases, including 396 local infections, raising the total caseload to 99,075, according to the Korea Disease Control and Prevention Agency (KDCA).

The country added one more death from COVID-19, increasing the total to 1,697. The fatality rate was 1.71 percent, the health agency said.

The daily caseload slightly fell from 456 on Sunday and 452 on Saturday but shows no signs of letting up. After spiking to the 600s in February, the figure had stabilized to as low as the 300s recently.

Daily infections fell to the 300s on Monday and Tuesday last week, but they rebounded to the 400s on Wednesday.

To curb the pandemic in the densely populated greater Seoul area, which is home to roughly half of the country's 52 million population, the KDCA extended virus curb measures that were set to expire on March 14 for two weeks until March 28.

Health authorities said they will decide Friday whether to once again extend the current virus curbs by another two weeks, but given the current situation, the measures are highly likely to be extended.

The country is also working to finalize a new four-tier social distancing system by the end of this month. Authorities say the revamped virus curbs, however, will be implemented after the virus curve sharply flattens.

The greater Seoul area has been under the current Level 2 social distancing measures, the third highest in the five-tier curbs, since February. The measures include attendance caps at schools, religious activities and sports events.

Health authorities plan to step up the AstraZeneca COVID-19 vaccine rollout following the European Medicine Agency's announcement that there is no evidence suggesting a correlation between the vaccines and blood clots found in some recipients.

The use of the vaccine has been suspended in more than a dozen European countries, including Germany, France and Italy, after reports of blood clots in people who received AstraZeneca products.

On Monday, the Korea Advisory Committee on Immunization Practices (KACIP), an independent panel of experts, said the AstraZeneca vaccine has nothing to do with the blood clots found in some vaccine takers and the vaccine rollout will continue.

But the committee acknowledged that two out of 10 cases of serious allergic reaction were due to the AstraZeneca vaccine.

The KACIP's announcement is in line with the assessment by EMA and the World Health Organization.

South Korea is set to begin administering the AstraZeneca vaccine to inpatients of nursing homes and long-term care hospitals who are aged 65 and older Tuesday.

Under the country's vaccination program that started Feb. 26, a total of 12 million people will be vaccinated by the end of June. Foreigners also will be inoculated under the program.

The country aims to achieve herd immunity by November.

A total of 676,607 people have been given COVID-19 vaccine shots as of Sunday. This accounts for around 1.3 percent of the country's population and 84.6 percent of those who are advised to be vaccinated by the end of March.

AstraZeneca's vaccine accounted for 619,100, while Pfizer's took up 57,507.

On Saturday, the country began administering the second Pfizer shots. The second round of shots for AstraZeneca's vaccine is expected to begin in late April.

A total of 9,703 cases of side effects after vaccinations have been reported, but most of them have turned out to be mild symptoms such as headache, fever and nausea.

Sixteen deaths after vaccinations have been reported, the KDCA said.

The country has added 36 variant cases since March 15, bringing the total to 249.

In other efforts to contain the virus, health authorities extended the ban on passenger flights arriving from Britain, which has been in place since Dec. 23, until April 1 to block the new virus variant that was first identified there.

All foreign arrivals have been required to present certificates of negative polymerase chain reaction (PCR) tests taken within 72 hours of their departure for South Korea since late February. They are also required to undergo a 14-day isolation period upon their entry into the country.

Of the new locally transmitted cases, 108 came from Seoul and 143 were reported from Gyeonggi Province that surrounds the capital. Incheon, 40 kilometers west of Seoul, reported 10 more cases. The three areas that make up the greater Seoul area accounted for 66 percent of all locally transmitted cases.

The number of imported cases came to 19, up from 12 the previous day. Cases from Asian countries except for China stood at eight, with cases from Europe, the United States and Africa at six, four and one, respectively.

The number of seriously or critically ill COVID-19 patients was 103, down one from the previous day.

The total number of people released from quarantine after making full recoveries was 90,611, up 283 from a day earlier.

South Korea has carried out 7,355,964 COVID-19 tests, including 23,250 the previous day. (Yonhap)