South Korea has arranged to buy coronavirus vaccines for 23 million more people, its prime minister said on Tuesday, a day after authorities decided to scale back initial vaccination plans, citing delays and efficacy concerns.

The deals include vaccines from Novavax Inc. for 20 million people and Pfizer products for 3 million, bringing the total number of people to be covered to 79 million, Prime Minister Chung Sye-kyun said.

"The government has been working to bring in sufficient early supplies, but there is growing uncertainty over our plan for the first half due to production issues with global drugmakers and international competition to adopt more vaccines," he told a televised meeting.