The next phase of South Korea’s COVID-19 vaccination campaign will not begin in earnest until late July, when 50-somethings finally become eligible, according to the Korea Disease Control and Prevention Agency on Thursday. Those younger than 50 will get their chance in August.

July will mainly focus on delivering first doses to 60- to 74-year-olds and essential workers whose June appointments got canceled or delayed due to a supply shortage. There are some 170,000 such people who are already eligible but still waiting for their shots.

First-dose recipients due for second doses will be given priority as well. The interval between the two doses is 11 to 12 weeks for the AstraZeneca vaccine, and three weeks for Pfizer’s.

“Mid-June to July will be a time for preparing the full-scale rollout that’s set to begin in August,” Jeong Eun-kyeong, head of the Korea Disease Control and Prevention Agency, told a news briefing. “This summer most Koreans will be able to access vaccinations in due turn.”

Late July continuing through August is when people in their 50s, who are next in line for vaccinations, will get their turn. The vaccines will first reach people in their late 50s from the last week of July, and then get to those in their early to mid-50s from August.

High school seniors, who are sitting the college entrance exam in November, will also be up for shots in August. People with health conditions and disabilities will get their shots at around the same time.

This leaves people in their 40s and younger coming in last, as they are not considered to be at high risk of severe complications from the infection. Unlike other priority groups, people under 50 are not preassigned a slot and must book their vaccine appointments through the online reservation system from August. The appointments are to be filled on a first-come, first-served basis, much like how bookings for leftover doses currently work.

So far, Korea’s vaccination efforts have targeted seniors aged 60 and above, pandemic front-liners, former and current members of the military and other essential workers.

In a change of strategy, Korea is allowing the mixing of vaccines under limited circumstances.

For instance, from next month on, following up a first dose of the AstraZeneca vaccine with a vaccine from another brand is allowed if the same vaccine is out of stock. But in principle, the national advisory committee on immunization practices recommends completing the dosing regimen with the same vaccine where possible. 

As such, people who received first doses of the AstraZeneca vaccine after mid-April will be offered the Pfizer vaccine instead to complete the series for most of July when supplies are expected to run low. Depending on which products are available at the time, people may be given the choice to stick with the same vaccine or switch to something else.

Thursday’s announcements did not include a specific delivery schedule for the rest of around 170 million vaccine doses that Korea secured either through deals with companies or through COVAX, an international vaccine-sharing program. But KDCA head Jeong said supplies for 10 million people from four different companies -- AstraZeneca, Pfizer, Moderna and Johnson & Johnson -- were due to arrive sometime in July.

“At least 60 million doses will be arriving in the third quarter, which will be sufficient to carry on with the vaccination plan in time,” she said, without specifying which vaccines they might be.

Since the vaccination campaign kicked off on Feb. 26, over 14 million people -- more than a quarter of Korea’s 51 million population -- have received one dose of a vaccine. The number of fully vaccinated people was 3.7 million, or 7 percent of the population.

Korea’s ultimate goal is to give at least one dose to 70 percent of its people by September and eventually reach herd immunity by November, or earlier if possible.

By Kim Arin (arin@heraldcorp.com)