South Korea has signed deals with Johnson & Johnson's Janssen and Pfizer to purchase coronavirus vaccines, with a goal of starting vaccinations in the second quarter of 2021, health authorities said today.

The government will buy vaccines for 10 million people from Pfizer and 6 million from Janssen, which was up from its initial plan for 4 million people, according to the Korea Disease Control and Prevention Agency (KDCA).

The government formally struck a purchase deal with AstraZeneca in late November and made an advance payment of 85 billion won (US$77.6 million) in October to the World Health Organization's global vaccine project, known as COVAX.

The government plans to sign contracts next month with Moderna and COVAX to secure vaccines for 10 million people from each, the KDCA said.

Vaccines by AstraZeneca, Pfizer and Moderna require two shots for immunization, and Janssen's vaccine requires one shot.

The government has set a goal of securing vaccines for 44 million people, enough to cover 88 percent of the nation's population, but the purchase deals are expected to cover 46 million with increased supplies from Janssen.

AstraZeneca's vaccines will be first shipped around February and March, followed by Janssen's in the second quarter of 2021 and Pfizer's in the third quarter, according to health officials.

Prime Minister Chung Sye Kyun said the government plans to start the vaccine program in the second quarter of next year, vowing to mobilize all resources to advance shipments of the vaccines for the goal.

"The government will pay thorough attention to make sure that the public can be vaccinated as soon as possible, without any anxiety, while carefully studying the safety and effectiveness of the vaccines administered (overseas)," Chung said during an interagency meeting on the coronavirus pandemic response.

The announcement came amid growing criticism over the Moon Jae In administration's vaccine procurement program. Critics argued that South Korea is lagging behind other nations in securing the supply of vaccines due to Moon's "miscalculation" of the situation.

A medical worker at a temporary screening station today in South Korea.

South Korea secures 16m Janssen and Pfizer coronavirus vaccines