Prime Minister Han Duck-soo speaks during a virus response meeting at the government complex in Seoul, July 13. Yonhap

Prime Minister Han Duck-soo said Wednesday that the government will expand eligibility for the fourth COVID-19 vaccine shot to people aged 50 and older as well as people aged 18 and older who have underlying health conditions.

The move comes as the nation is facing another wave of virus resurgence, driven by the fast spread of the highly contagious mutation of the omicron strains, BA.5, which is known to be more contagious and better able to escape immunity compared with earlier versions.

"With the spread of BA.5 mutations, the resurgence is starting faster than originally expected," Han told a virus response meeting.

Currently, people aged 60 and older and people who have an immune disorder are eligible for fourth COVID-19 vaccine shots.