The country will face another supply shortage of Moderna COVID-19 vaccines, with less than half of the expected deliveries to arrive this month.

Vaccine authorities said on Monday that Moderna recently notified them that it can supply less than half of the eight-point-five million doses it was supposed to deliver in August, due to production problems.

Out of 40 million doses South Korea has purchased from Moderna, 112-thousand doses were delivered in the first half of the year. Two-point-34 million doses have arrived since July and another nine-point-16 million doses were scheduled for August.

The government plans to lodge a complaint and send a team led by Second Vice Health Minister Kang Do-tae to call for a swift normalization in the supply.

Due to the inevitable shortage, people scheduled to get their second Moderna or Pfizer vaccine shot after August 16 will have their interval extended from three weeks for Pfizer and four for Moderna to six weeks.

Officials said the extension will not apply to third-year high school students, school staff and others preparing for university admissions to prevent changes to the nationwide College Scholastic Ability Test(CSAT) in November.