High school seniors began receiving their coronavirus shots Monday, becoming the first teenagers in the country to be inoculated.

According to the Education Ministry and health authorities, high school faculty members including teachers, school administrative staffers and other workers who are in close contact with students started getting their shots Monday along with the teenagers.

The students and teachers are getting Pfizer’s vaccine. The Ministry of Food and Drug Safety approved its use for teenagers aged 16 or older in March.

First doses of the vaccine are being administered to some 630,000 students and teachers from 3,184 schools across the country at 290 inoculation centers through July 30. This cohort can get second doses Aug. 9-20, with the authorities aiming for its full vaccination before the second semester begins.

“I was worried about getting the vaccine. There was a sense of worry among my friends, too,” high school senior Yoon Jin-seo said after getting a vaccination.

“I figured it would be better to take (the College Scholastic Ability Test) safely after getting the jab, so I decided to receive the inoculation. (The shot) did not hurt as much as I expected.”

Even though the Education Ministry and health authorities worked closely to make things go smoothly, there were hiccups on the first day.

A system error forced some 700 high school seniors and faculty members to wait for over an hour at a vaccination center set up in a gym in Bucheon, Gyeonggi Province. Medical workers had to cross-check the vaccination list before administering the shots, but the list of students and faculty members who had signed up for the inoculations could not be found in the local health authorities’ system.

A Bucheon City official said the vaccination list had been uploaded on a different government database. The local authorities had to ask the Korea Centers for Disease Control and Prevention, which controls the vaccination lists, to correct the error. Vaccinations began at around 10:40 a.m. after the problem was solved.

Visiting a vaccination center in Gimpo on Monday, Education Minister Yoo Eun-hae said, “Keep a close eye on abnormal reactions after inoculation. If chest pain and difficulty breathing continue, you should seek medical attention immediately. Also avoid high-intensity exercise and activities for about a week after inoculation.”

In the US, there have been rare reports of inflammation of the heart -- approximately four cases of myocarditis or pericarditis for every million doses administered -- after mRNA vaccines such as Pfizer and Moderna. The complication has occurred mostly in male adolescents and young adults aged 16 or older, and is more common after a second shot.

Meanwhile, the government is opening up the online vaccination booking system to 3.9 million people aged between 50 and 54 this week.

To prevent system delays and abrupt closures due to the limited supply of vaccines, the government divided the group in two.

For people aged 53 and 54, the vaccine booking system opened Monday at 8 p.m. People aged between 50 and 52 can make appointments starting Tuesday at 8 p.m.

Reservations will be open through the system from Wednesday through Saturday for anyone 50-54. Those who make reservations this week will receive the Moderna vaccine Aug. 16 through 25.

The government’s vaccine reservation system experienced a delay when it became available for 55- to 59-year-olds at midnight on Monday last week as tens of thousands of people rushed to book shots.

The government then closed the reservation system after 1.85 million people made appointments, saying it was a temporary halt due to a limited vaccine supply. The booking system reopened two days later.

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