The health authorities are on alert over the first discovery in South Korea of a more transmissible variant of the new coronavirus from Britain, as Korea struggles to overcome its third and deadliest coronavirus wave to date.

According to the Korea Disease Control and Prevention Agency, three Korean nationals who arrived here from Britain last week were confirmed Monday morning to have the new coronavirus strain, which is believed to be 70 percent more transmissible than the original.

Authorities are also investigating to determine whether an elderly Korean man who posthumously tested positive for COVID-19 after returning from Britain may also have contracted the new variant, along with three members of his family.

The COVID-19 variant, thought to have originated in London in mid-September, is being researched to see whether it is deadlier than the original strain or has any other unique properties.

Britain has imposed heavy restrictions on its population to fight the new variant, and Korea announced that it will suspend flights arriving from the country for an extra week after its original deadline, Dec. 31 at midnight.

The introduction of the new COVID-19 variant is alarming to officials, who were already struggling to manage the situation as the country encountered its most threatening coronavirus wave since January.

“We are carrying out strengthened measures for all entries to prevent the influx of the COVID-19 variant from Britain and South Africa,” said KDCA Commissioner Jeong Eun-kyeong in a press briefing Monday.

“We are also looking to launch strengthened virus control measures domestically after discovering the first case here.”

Korea on Monday announced 808 new coronavirus cases -- 787 locally transmitted and 21 imported from overseas -- raising the total number of cases recorded in Korea to 57,680.

Monday’s tally marks a drop from 970 cases reached the previous day, largely because the country carried out fewer diagnostic tests over the Christmas holiday weekend. The country had reported daily figures around the 1,000 mark for six days in a row after adding 867 cases Tuesday.

The number of locally transmitted cases reported Monday reached its lowest level since 682 cases were reported Dec. 14.

“The number of locally transmitted cases has entered the 700 level for the first time in a while, but we will have to see what that really indicates,” said Ministry of Health and Welfare spokesperson Son Young-rae in a press briefing Monday.

“The number of tests dropped over the weekend, so whether today is a point to see the number of cases start falling, we will have to stay patient.”

As the daily rise in the number of cases remains high, Korea announced on Sunday that it will maintain its toughened social distancing rules until Jan. 3, putting the capital region of Seoul, Incheon and Gyeonggi Province under Level 2.5 rules and the rest of the country under Level 2.

Authorities additionally implemented much stronger restrictions for the winter holiday season, especially for private gatherings and travel.

The country closed all of its ski resorts, ice rinks and sledding hills, while the capital region banned private gatherings of five or more people until Jan. 3.

Enforcing strict virus control measures in the capital region has been the key focus for local authorities as the Greater Seoul area is responsible for close to 60 percent of all cases in Korea to date, accounting for 67.3 percent of new daily cases announced Monday.

Seoul announced 297 new cases, followed by Gyeonggi Province with 188 cases and Incheon with 45 cases.

Officials also urged people to take extra precautions at home, as around 25 percent of COVID-19 patients reported over the past month were infected through family members.

Prime Minister Chung Sye-kyun said in a meeting Monday that officials found a pattern of economically active people in their 40s and 50s transmitting the virus to family members.

Some 44 percent of the recently confirmed COVID-19 patients in their 20s or younger were found to have been infected through contact with members of the same household.

“The key to curb today’s resurgence is effectively carrying out virus control measures at homes, workplaces and social activities,” Chung said.

“I ask the middle-aged and the elderly to thoroughly carry out sanitation rules at their workplaces and social boundaries to protect the lives of their beloved family members.”

And to prevent additional fatalities during this deadliest wave of the pandemic, Korea is continuing its search for available hospital beds to provide treatment for severely ill coronavirus patients.

By the end of Sunday, Korea had reported a total of 819 deaths from the novel coronavirus, up 11 from a day earlier, with more than a quarter of them reported this month alone.

The number of COVID-19 patients in serious or critical condition reached 295, up from 293 people a day earlier. A total of 39,268 people have been released from quarantine after fully recovering.

The Health Ministry said there were 153 available hospital beds across the country for severe COVID-19 patients, with 68 of them in the capital region. Some 63 were people awaiting beds as of the end of Sunday.

Meanwhile, Korea added 21 cases from overseas on Monday, raising the total to 5,318 cases. Three new cases each were from the United States, Britain and India, and 12 of the new imported cases were found in foreign nationals.

More than 4.03 million COVID-19 checks had been conducted since Jan. 3 and 31,895 samples were taken Sunday, down from 36,997 samples a day earlier.

And after facing public backlash for falling behind other countries in securing vaccine supplies, the government restated that it has focused on securing supplies of vaccines for months and that inoculation will start no later than in most countries.

The Blue House said in a statement Monday that the government expects to provide vaccines for medical workers and elderly people by February and that local development of treatments and vaccines is accelerating so that they can earn approval and start production on time.

It denied accusations that the government failed to secure enough vaccines for its people or will face delays in providing those made overseas to Koreans, saying it has consistently worked with experts to set strategies and goals.

Korea has so far decided decided to purchase vaccines for 46 million people and signed official contracts for 36 million people, KDCA said. The government is in talks with developers to purchase more vaccines for 10 million people.

KDCA Commissioner Jeong said the amount of vaccine to be brought into Korea starting first quarter next year will be sufficient to form group immunity by September and before seasonal influenza goes viral again.

“We are making secretive negotiations with vaccine developers and have some nondisclosure obligations to follow, and some changes are possible in the detailed volume of vaccines and when to supply them for developers,” Jeong said.

“But we will make sure to abide by our standards and do our best to manage the supply and distribution of vaccines.”

By Ko Jun-tae (ko.juntae@heraldcorp.com)