hankyoreh

Korea Disease Control and Prevention Agency (KDCA) Commissioner Jung Eun-kyeong speaks during an expert briefing about the vaccination of people aged 18 to 49 on Thursday. (Yonhap News)

COVID-19 vaccinations for South Korean residents aged 18 to 49 began nationwide Thursday.

The current reservation rate is 67%, with 10.15 million registered out of roughly 15.1 million eligible in that age group, not including those who have already received their shots. Those being inoculated through Sept. 5 will be receiving the Pfizer vaccine, while no decision has yet been made on what vaccines will be provided afterward.

In an expert briefing streamed live Thursday afternoon on YouTube by the COVID-19 vaccination response team, questions about the vaccination of people aged 18 to 49 were answered by Chonnam National University Hospital cardiovascular medicine professor Kim Kye-hun, Korea University Ansan Hospital infectious disease professor Choi Won-seok, Gachon University preventive medicine professor Jung Jae-hun, and team leader and Korea Disease Control and Prevention Agency (KDCA) Commissioner Jung Eun-kyeong.

Hankyoreh (Hani): Among young people, the rates of severe symptoms and death [from COVID-19] are apparently quite low. Should these people get vaccinated even when it means accepting the risk of adverse reactions such as myocarditis or pericarditis?

Kim Kye-hun: Without question, they need to get vaccinated. The incidence rates of myocarditis and pericarditis are very low, whereas the effects of the vaccines in preventing infection, severe symptoms and death are high.

As of [Thursday], the adverse reaction reporting rate among [vaccine recipients] aged 18 to 49 stands at 0.53%. Ninety-seven percent of those involved mild symptoms such as headache and muscle pain.

There are, of course, reports that myocarditis and pericarditis happen more frequently with mRNA-based COVID-19 vaccines than with other virus vaccines. Most of those involved people under 30, and it happens seven times more frequently in males than in females. So if the number of young people vaccinated rises, then that incidence is also expected to rise.

But if you look at the data from the US, the incidence rate for post-vaccination myocarditis among all age groups is 3.5 per million, which is extremely low. We also need to take into account the fact that myocarditis also occurs surprisingly often with people who contract COVID-19.

Jung Eun-kyeong: Our [vaccination] team analyzed the [the rate of COVID-19 patients who developed critical symptoms or died] in 35,826 confirmed patients aged 18 to 49 between May 1 and July 24. The results showed that the rate was 0.85% among unvaccinated patients aged 18 to 49 but 0.17% for patients who had been fully vaccinated.

Hani: Apparently, you can contract COVID-19 even when you’ve been vaccinated.

Jung Eun-kyeong: Currently, the rate of confirmed COVID-19 diagnosis after full vaccination in South Korea is 0.035%.

Hani: What should people do if they experience possible signs of myocarditis or pericarditis after vaccination, such as chest pain or difficulty breathing?

Kim: A myocarditis diagnosis may require a special blood test or magnetic resonance imagining. Pericarditis can be diagnosed through a heart ultrasound. Those diagnoses are difficult for neighborhood clinics to make, so we recommend that people visit at least a semi-general hospital. Most of the myocarditis and pericarditis cases have been mild, but even when they become severe, most patients fully recover.

Hani: Is it OK to get vaccinated if I’ve had myocarditis or pericarditis in the past?

Kim: If you’ve fully recovered, you can go ahead and get vaccinated. It’s a good idea to check with your family doctor to see whether you’re fully recovered before you get the vaccine.

Hani: If I developed possible myocarditis or pericarditis symptoms after my first shot, should I still get my second?

Kim: In that case, I’d advise holding off on vaccination. Right now, the question of what mechanism causes post-vaccination myocarditis and pericarditis is still a matter of speculation. It could recur after the second dose, so in those cases, you should hold off on being vaccinated and take care not to contract COVID-19.

Hani: Do mRNA vaccines pose a greater risk of anaphylaxis?

Choi: It is a bit higher than for the other vaccines. According to recent US reports, it occurs at a rate of 2.5 to 4.7 cases per million. It’s not so high that you should be overly concerned, but it is a little higher than for something like the flu vaccine. After you’ve been vaccinated, it’s a good idea to stay there for 15 to 30 minutes and watch for any adverse reaction.

Hani: The interval between Pfizer vaccine doses is originally supposed to be three weeks. For Moderna, it’s four weeks, but in South Korea it’s six weeks. Does that cause any issues in terms of effectiveness?

Choi: The best approach is to follow the established interval. But it does not appear that the effectiveness declines if the interval is increased.

Typically, the problems occur when the interval between doses is shortened. Also, if you look at recent studies, some report that an interval of 6 to 14 weeks between Pfizer doses shows a similar or even greater immune response compared with a three-week interval.

Hani: I made my reservation through the regular system based on my birthday. Can I still reserve a leftover vaccine?

Jung Eun-kyeong: You can. You should just be aware that if you reserve a leftover vaccine, your previous reservation will be automatically canceled.

By Choi Ha-yan, staff reporter

Please direct comments or questions to [english@hani.co.kr]