A Korean delegation of government officials on Friday departed for the United States to meet with Moderna representatives over the delay in shipments of their COVID-19 vaccine.

The delegation of four high-ranking officials, including Second Vice Health Minister Kang Do-tae and Presidential Secretary for Social Policies Ryu Geun-hyuk, will meet with Moderna representatives at the pharmaceutical and biotechnology company’s headquarters in Cambridge, Massachusetts, on Friday afternoon, US time.

“We will express regret over the change in the supply of vaccines from Moderna and discuss ways to ensure a more stable supply of vaccines for the future, including the incoming supply,” Kang told reporters at Incheon Airport.

The government delegation is scheduled to arrive back in the country on Sunday afternoon and is expected to announce the results of the meeting later in the day or on Monday.

Earlier this week, the government announced that Moderna will be sending less than half of the 8.5 million vaccine doses it had pledged to ship over in August. Health Minister Kwon Deok-cheol said in an emergency briefing that Moderna apologized for the delays in shipments and explained that other countries were also affected by the shortage. The US drugmaker cited a setback in production as the reason for the delays, but did not elaborate further.

It is not the first time Moderna has failed to meet the promised delivery schedule.

In July, the US firm said it was unable to ship over 1.96 million doses by the end of July as planned, and only 1.3 million doses of the batch had arrived in Korea as of Aug. 7.

The government signed a contract with Moderna to bring in a total of 40 million doses of its vaccine in 2021. Of them, only a little over 6 percent, or 2.45 million doses, have been imported to Korea so far.

The delays have had a knock-on effect on Korea’s already sluggish vaccine rollout. The government has had to extend the period between the first and second jabs of two messenger RNA COVID-19 vaccines -- Moderna and Pfizer -- to ration scarce supply.

Starting next week, the administrations of the two shots will be spread six weeks apart, instead of the previous three to four weeks.

High school seniors and other priority groups in the education sector will be exempt from the longer interval as schools prepare to allow more students for in-person classes in the second semester.

Despite the delays in vaccine supply, Prime Minister Kim Boo-kyum said Friday that the government will go all out to achieve a 70 percent first-round vaccination rate before the Chuseok holidays, which will begin Sept. 20.

According to the Korea Disease Control and Prevention Agency, so far nearly 22 million people, or 42.1 percent of the population, have received their first shot, while 8.9 million have been fully inoculated.

By Kan Hyeong-woo (hwkan@heraldcorp.com)