SEOUL (REUTERS) - South Korea announced on Friday (July 30) plans to expand its coronavirus vaccine roll-out to people aged 18 to 49, as the country grapples with record high daily cases driven mostly by infections in the unvaccinated younger population.

South Korea has been struggling to boost its immunisation drive amid supply shortages and shipment delays, with about 36.5 per cent of its 52 million people having received at least one dose, while just 14 per cent are fully vaccinated.

It aims to immunise over 70 per cent by September as it vaccinates the 18 to 49-year-olds with Moderna or Pfizer/BioNTech's products in August, Korea Disease Control and Prevention Agency director Jeong Eun-kyeong told a briefing.

The country's vaccination campaign gave priority access to high-risk medical workers and the critically ill and the elderly people. It began inoculations for people in their 50s this week.

Mr Jeong said that while the country is on track to meet its vaccination target, changes to the vaccine shipment schedule may be inevitable due to global supply shortage.

South Korea's vaccination plan appeared to hit a snag on Monday after Moderna told the government that shipments of its vaccine promised to the country would be delayed.

The delayed 1.3 million doses of Moderna vaccine will arrive as early as Aug 6, and agreement was made on a separate 8.5 million shots for the same month, Prime Minister Kim Boo-kyum said.

The mortality rate stands at 1.06 per cent as at Thursday, and the number of severe cases at 299. Experts had called for tougher social distancing rules to bring down the number of severe cases that has doubled in three weeks.

South Korea reported 1,710 new infections for Thursday, bringing the tally to 196,806 infections, with 2,089 deaths.