New COVID-19 variants pose an imminent threat to South Korea’s efforts in curbing the pandemic with a vaccine rollout still weeks away, health authorities say, as experts urged for tighter border restrictions to prevent their arrival here.

Korea Disease Control and Prevention Agency chief Jung Eun-kyeong voiced concerns over these variants, which appear to be more transmissible, saying they are “threatening Korea’s progress in the pandemic.”

“Increasingly more countries are now reporting cases of the new variants, and Korea, too, has confirmed 54 such cases to date,” she said.

The number of cases of the UK variant rose to 40, after it first landed in Korea in late December, the KDCA commissioner said. There have been five cases of the Brazil variant and nine of the South African variant.

Korea will now require everyone -- including Korean citizens -- departing from Africa to submit proof of being negative for COVID-19, she said.

“The global prevalence of the variants signals they could proliferate rapidly in the Korean population once they take hold,” Jung said, adding that more genetic sequencing will be conducted to detect their presence at the border and in communities. In January, Korea sequenced about 500 samples, which is only about 0.03 percent of all cases diagnosed over the month.

Korea needs to both block arrivals to stop importing new variants and be ready to quickly update the vaccines, according to preventive medicine professor Dr. Jung Jae-hun at Gachon University.

“The variant first identified in South Africa is anticipated to be a huge threat to immunization efforts,” he said. “This particular variant is reported to reduce the efficacy of AstraZeneca, Novavax and Johnson & Johnson (Janssen) vaccines. The threshold for herd immunity will also rise.”

South African health authorities suspended the use of the AstraZeneca vaccine Sunday, local time, over data showing its compromised protection against the variant found there.

“A considerable proportion of the passengers are placed in their respective homes or other accommodations not overseen by authorities for the two-week quarantine upon arrival. As seen in recent instances, they are highly likely to pass the infection to cohabitants over the period,” Jung pointed out.

“We should have all passengers quarantine in facilities that are overseen by authorities to close these loopholes,” he said. According to the Ministry of Interior and Safety data, 26,999 passengers were home-quarantining and self-monitoring as of 6 p.m. Sunday.

Respiratory disease specialist Dr. Chun Eun-mi of Ewha Womans University Medical Center suggested charging passengers for mandatory PCR tests, which cost approximately 80,000 won ($71.50) each, to further discourage nonessential travel.

“For the past year Korea has been testing and treating everyone arriving here free of charge regardless of travel purposes. If passengers have to shoulder some of the costs, it can help sift out those who may be coming here for nonessential reasons,” she said.

The vaccination timeline unveiled by the government so far is still somewhat vague, Chun pointed out.

In a response to The Korea Herald’s question on the exact date for the first shipment of COVID-19 vaccines here, Jung of the KDCA said 1.5 million doses of the AstraZeneca vaccine will be arriving in the last week of February. As the vaccine requires two doses per treatment, the amount would be enough to cover around 750,000 people. Up to 4.4 million doses of the AstraZeneca vaccine are expected to be available in phases between late February and June.

Although Jung had said 117,000 doses of the COVAX-supplied Pfizer vaccine, which will be enough for nearly 60,000 people per its two-dose regimen, will be arriving “sometime in the latter half of February, following the Seollal holiday at the earliest,” the exact delivery date is still unknown.

The number of new cases dropped to a near two-month low of 289 on Monday, bringing the cumulative total to 81,185, according to the KDCA. Three more deaths were announced, with the toll reaching 1,474.

By Kim Arin (arin@heraldcorp.com)