Nearly half of new COVID-19 cases in South Korea over the past two weeks were breakthrough infections, health authorities said Tuesday.

There were 8,336 breakthrough cases out of 17,325 new COVID-19 patients, or 48.1 percent, between Oct. 17 and Oct. 30, the Korea Disease Control and Prevention Agency (KDCA) said. Breakthrough infections are those who test positive even after receiving the full-dose vaccine regimen.

The rate of breakthrough cases occurring in people aged in their 70s was the highest, with 8 out of 10 new COVID-19 patients, the KDCA said.

The rate was the lowest among those aged between 18 and 29, with only 19.7 percent of the new COVID-19 patients, it said.

Since the country's nationwide inoculation campaign began in late February, 41.63 million people, or 81.1 percent of the country's 52 million population, have received their first COVID-19 vaccine shots. The number of fully vaccinated people came to 39.49 million, or 76.9 percent. (Yonhap)