SEOUL—South Korea authorized the use of Novavax Inc.’s vaccine on Wednesday and will begin treating coronavirus patients with Pfizer’s antiviral pills on Friday. Some 630,000 of Pfizer’s Paxlovid pills, enough for 21,000 people, arrived on Thursday to be distributed to 280 pharmacies and 90 residential treatment centers, the Korea Disease Control and Prevention Agency (KDCA) said. The pills, which were authorized for emergency use in December, will begin being used in treatments for more than 1,000 people per day starting on Friday, the health ministry said. “By priority, oral treatment is planned to begin first for patients aged 65 or older, or patients with reduced immunity at home and residential treatment centers,” a ministry spokesperson told a briefing. Each patient was advised to take three pills at a time twice a day for five days, and another batch for 10,000 people, or 300,000 pills, are expected to arrive later in …