South Korea said Wednesday COVID-19 vaccinations for people in their 50s will be pushed back to accommodate uncertain vaccine deliveries.

The first-dose vaccinations of over 7 million people in their 50s, which were supposed to be completed by Aug. 7 under the initial plan, have been delayed by around two weeks to Aug. 25, the Korea Disease Control and Prevention Agency’s commissioner Jeong Eun-kyeong said in an emergency briefing.

Wednesday’s announcement comes after Moderna vaccine reservations for 55- to 59-year-olds closed abruptly Monday afternoon after opening up at midnight.

“The vaccine registration began at a time when the supplies for the final week of July were still uncertain,” Jeong said. 

The agency chief then apologized for all those who couldn’t obtain an appointment due to the system closing in less than a day despite previously announcing that they had until Saturday to sign up.

She added that the vaccine registration system for the rest of the people in their mid to late 50s would open again later in the day at 8 p.m. -- without confirming if the supply shortages have been eased in the last two days. The agency said on Monday that there were only around 807,000 doses of the Moderna vaccine in the country.

Asked if there would be enough vaccines for both rounds of Moderna vaccinations, which are given four weeks apart, for 50-somethings, Park Hye-kyung, an agency official, replied in the same briefing, “That is the plan.”

“But depending on the supplies available, there is a possibility of some adjustments,” she said.

On June 17, the government’s committee on COVID-19 vaccination said a combined total of 10 million doses of AstraZeneca, Pfizer, Moderna and Johnson & Johnson vaccines would be arriving here in July.

Of the 10 million doses, 2.88 million doses -- 2.13 million doses of Pfizer vaccine and 750,000 doses of Moderna’s -- had made it into the country as of Wednesday, according to Lee Ki-il of the Ministry of Health and Welfare. The remaining 7.12 million doses “will also get here without fail over the remainder of the month,” he said in a briefing held the same day.

Lee added that the details of the vaccine delivery timeline could not be revealed due to confidentiality agreements with pharmaceutical companies. 

Yet again, Korea posted a record one-day high of 1,615 cases on Wednesday, surpassing the previous wave’s peak of 1,240 cases in mid-December. An average of 1,308 cases have been reported each day over the past week.

Other metrics suggest the latest wave of COVID-19 could still be far from peaking.

Last week’s R value, the expected number of secondary cases generated per single infection, was slightly over 1.2 nationwide. An R above 1 indicates that the epidemic is growing. The rates of positivity in testing rose to over 6 percent over the weekend, from 2 to 3 percent earlier this month. The World Health Organization advises that the percentage of positive tests should remain at 5 percent or lower.

As cases continue a streak of record-highs, contract tracers are scrambling to catch up and hospital beds are filling up.

Contact tracing was failing for a third of the over 7,000 newly diagnosed patients, meaning that they do not know from whom or where they might have contracted the infection. 

Some 80 percent of patients who weren’t seriously sick at the time of diagnosis had to wait at home for at least a day before they could be admitted to care facilities. In Seoul, which logged more than 1,000 cases in a single day for the first time on Wednesday, patients were being moved to hospitals elsewhere.

Delta, known as the most transmissible variant of COVID-19 yet, showed up in one in four patient samples analyzed, according to the weekly report posted Tuesday.

Not enough older people, who are at higher risk of severe complications from the infection, are protected with full vaccination to keep hospitalizations and deaths down. Only 39 percent of people in their 70s were fully vaccinated against COVID-19. For those in their 60s, the rate was much lower at less than 5 percent.

The vaccination campaign that began on Feb. 26 delivered at least one dose of a vaccine to over 30 percent of 51 million people in the country to date. The percentage of people who are fully vaccinated stood at 11 percent. The vaccination pace slowed to about 90,000 doses a day in the past week, before picking up to 195,125 doses for the whole day on Tuesday.

Still, the ministry is confident that the current, fourth wave “will stabilize at the end of two weeks of intensive social distancing” that Seoul and cities nearby have been placed under.

“So I urge the people of the wider Seoul area to please refrain from socializing and nonessential outings. Reducing contact is key,” said Lee of the ministry. “In two weeks, things will be under control again.”

Since the pandemic began, at least 171,911 people in Korea have been infected, of whom 2,048 have died.

By Kim Arin (arin@heraldcorp.com)