South Korea's new coronavirus cases rebounded to over 50,000 on Tuesday amid concerns over a possible outbreak of a "twindemic" of the pandemic and seasonal influenza this winter.

The country reported 58,379 new COVID-19 infections, including 68 from overseas, bringing the total to 25,615,667, the Korea Disease Control and Prevention Agency (KDCA) said.

The daily caseload fell below 20,000 on Monday after staying below 40,000 the previous four days.

Last week, the government said it will expand booster shots against omicron variants to all adults aged over 18 amid concerns about the risks of a simultaneous outbreak of COVID-19 and the seasonal flu.

The country added 33 deaths from COVID-19, bringing the death toll to 29,209. The fatality rate was 0.11 percent. The number of critically ill patients remained unchanged at 288, the KDCA said. (Yonhap)