South Korea plans to administer COVID-19 vaccines to 22 million people of the general public aged between 18 and 59 starting next month as part of its inoculation campaign, health authorities said Thursday.

The Korea Disease Control and Prevention Agency (KDCA) announced the list of third-quarter vaccine recipients to achieve its goal of vaccinating 36 million people in the country of 51.3 million by September.

The country's vaccination campaign started on Feb. 26 with some virus-vulnerable groups and front-line medical workers being prioritized for inoculations.

Slightly more than 14 million people have received their first shots of COVID-19 vaccines here, accounting for around 27 percent of the country's population.

"Vaccinating general members of the population kicks off in full-scale in the third quarter," KDCA chief Jeong Eun-kyeong said, urging people to receive vaccines during their designated period to help the country achieve the goal of herd immunity by November.

People in their 50s will begin receiving their first shots in late July, with those aged between 18 and 49 in mid-August, the KDCA said.

Among the 18-49 age group, high school students to take the national college entrance exam and teachers aged under 30 at nursery schools, primary, middle and high schools will first get the shots.

A total of 170,000 people initially scheduled to receive their first shots in June but who failed to get inoculated due to supply issues will also be the first priority group in July, the KDCA said.

The KDCA said a total of 10 million doses of vaccines from four pharmaceutical firms --AstraZeneca, Pfizer, Moderna and Johnson & Johnson's Janssen -- are scheduled to arrive in the country in July.

The country has secured enough vaccines to inoculate about 100 million people.

The KDCA said it will also allow combining AstraZeneca and Pfizer vaccines in two-shot regimens among some groups starting next month to boost efficacy.

Major European countries and Canada have already allowed combining two mRNA vaccines interchangeably following safety concerns of the AstraZeneca vaccine earlier.

A total of some 760,000 people, including home-visit caretakers aged over 30, medical workers at neighborhood clinics and pharmacies, as well as other personnel, such as police officers and fire workers will be subject to such a two-shot schedule.

The group received the AstraZeneca vaccine as the first dose in April and will be followed by a Pfizer vaccine as the second dose after July 5, the KDCA said.

The authorities, however, said they can receive an AstraZeneca vaccine for the second booster if they do not want different vaccines.

The move is partially due to the belated delivery of AstraZeneca vaccines through the global COVAX scheme. Initially, some 835,000 AstraZeneca vaccines were to arrive in the country later this month, which was pushed back to after July.

The KDCA said while many studies are ongoing globally, there is no safety issue and some studies even suggest such a mix and match schedule may create higher antibody levels than two doses of a single vaccine.

A study published in Spain showed that vaccinating COVID-19 patients who have received an AstraZeneca jab and the Pfizer vaccine is safe and effective, and provides greater protection against the virus.

The neutralizing antibodies in the people who received a second dose of the Pfizer vaccine increased sevenfold compared with those who received just one AstraZeneca dose, according to the study.

In August, workers at key businesses, such as steelmaking and chipmaking, will be able to receive COVID-19 vaccines at their workplaces as part of efforts to reduce any disruptions caused by the virus outbreak among the employees.

On Thursday, the country reported 540 more virus cases, remaining in the 500s for the second day, the KDCA said. The total caseload increased to 149,731. (Yonhap)