Photo/Illutration A public sports facility area is taped off for the social distancing measures and precaution against the coronavirus in Seoul on Aug. 12. (AP Photo)

SEOUL--Prime Minister Kim Boo-kyum urged South Koreans on Friday to minimize holiday travel and asked companies to show flexibility in letting people work from home amid a worsening fourth wave of COVID-19 infections and a shortage of vaccines in the country.

The spread of the virus has accelerated as the highly transmissible Delta variant has become the dominant strain in the country, and authorities' contact tracing has been unable to keep track of transmissions over peak summer season for domestic travel.

The Korea Disease Control and Prevention Agency (KDCA) reported 1,990 new COVID-19 infections for Thursday, having reported its highest daily count of 2,223 on Wednesday. From early July daily cases for the first time rose above 1,100 and have kept rising. The government has said the current wave of infections has not peaked yet.

Total cases stand at 220,182, with 2,144 deaths.

Kim called on the public to minimize travels and gatherings in the next three days and urged those returning from holiday destinations to get tested for COVID-19 especially before clocking in for work.

"There have been many workplace clusters recently," Kim told a televised speech. "Please make sure the employees returning to work to check for symptoms like fever."

Under the current distancing rules, employers are advised to increase flexible staffing with 30 percent of staff working remotely.

Kim added the government will issue an administrative order to secure at least 5 percent of hospital beds for serious COVID-19 cases in 26 general hospitals in the capital Seoul and surrounding areas.

Priority vaccinations for the elderly helped the country to keep its mortality rate low at 0.97 percent as of Thursday, but severe and critical COVID-19 patients have been on the rise, prompting authorities to mandate hospitals to provide more ICU beds.

A government delegation led by Vice Health Minister Kang Do-tae left for Boston for talks with Moderna Inc. on Friday morning to express "profound regret" and protest against the U.S. vaccine maker's repeated shipment delays, health ministry official Son Young-rae told a briefing.

On Monday Moderna informed South Korea that it would only be able to deliver less than half the 8.5 million doses it had been due to ship in August.

South Korea has a contract for 40 million doses from Moderna and has received around 2.5 million so far.

South Korea has administered 42.8 percent of its 52 million population with at least one shot, while 17.4 percent have been fully vaccinated, KDCA data showed.