South Korea has finalized deals with Pfizer and Novavax for 46 million doses of COVID-19 vaccines, Prime Minister Chung Sye-kyun said Tuesday.

The prime minister told a government meeting that Korea on Monday evening signed the final contracts with Pfizer for 6 million more doses, in addition to the 20 million doses already ordered from the company, and 40 million doses from Novavax.

The extra purchases push the country’s reservoir of COVID-19 vaccines to 152 million doses, which will be enough for 79 million people. Based on the announcements so far, most of the vaccines will arrive between the second and fourth quarters.

Chung said 1 million doses of the Pfizer vaccine will be shipped here by the end of March, and that an unspecified amount of the Novavax vaccine will also be ready no later than June.

He explained that the government was securing more doses of the vaccines amid “growing uncertainties of vaccine availability in the first half of the year.”

In Monday’s briefing on vaccination planning, the Korea Disease Control and Agency chief Jung Eun-kyeong said people aged 65 or older will not be vaccinated at least after March, following a state regulator decision that cautioned against using AstraZeneca vaccine for older age groups. Korea’s early vaccine supplies are mostly from AstraZeneca.

Instead the first doses of the AstraZeneca vaccine will be offered to nursing home residents and workers under the age of 65 starting Feb. 26. Nursing home residents aged 65 or older, who are on top of the vaccination priority list, may be able to receive the vaccine depending on the results from a US study, Jung said.

The rollout with health care workers, which had been slated for late February, has also been pushed back to the second week of March.

These adjustments likely cause Korea to have a late start with vaccinations. In a Jan. 28 announcement, the government said 70 percent of the population would have been vaccinated by September.

Meanwhile, more cases caused by new virus variants are being reported just as the government has undone some of the social distancing restrictions put in place since December.

Over the weekend health authorities looked at 65 samples and found six more cases caused by new variants of COVID-19, all of them among international arrivals. Five of them were detected at the airport, and the other one was a business traveler who was exempted from the mandatory 14-day quarantine. The number of variant cases in Korea is now 94.

Korea is one of many countries around the world that are tightening its borders to keep out the threats posed by the variants. From Feb. 24, all arriving passengers, including citizens, are required to submit proof of a negative PCR result.

But the new travel restriction has loopholes, according to Democratic Party of Korea Rep. Choi Hae-young, who is on the parliamentary committee for health and welfare. “Transit passengers are not asked to present a negative test result, when it is very much possible to catch the coronavirus while aboard the airplane,” she said in a statement Tuesday.

Experts say Korea should ramp up efforts to manage the risk from the new variants.

Infectious disease expert Dr. Kim Woo-joo of Korea University agreed that Korea should up screening at the border and do more of genetic sequencing to stay ahead of the variants.

“Not all those arriving in the country are quarantined in government-designated facilities. Most are self-quarantining, in which breaches can go unnoticed,” he said.

“The variants, which appear to be more contagious and possibly even more lethal according to recent information, may soon begin to dominate local outbreaks if we don’t take the right steps.”

Respiratory disease specialist Dr. Chun Eun-mi said charging passengers for the COVID-19 tests or elongating the quarantine period to 3 weeks from the current 2 weeks could be a way of blocking those traveling here nonessentially.

“Korea’s borders have been leaky. It has never instituted a travel ban. Testing was also not compulsory for travelers at the end of the quarantine until recently,” she said. “Until we get a decent amount of the people here vaccinated, we have to toughen the controls as deemed necessary to spot and isolate new variants as they come in.”

Korea counted 457 more cases of COVID-19 -- 429 locally transmitted and 28 imported -- on Tuesday, according to the government update, bringing the cumulative total to 84,325. Seven more people died, making the death toll 1,534.

By Kim Arin (arin@heraldcorp.com)