The nation's chief adviser on infectious diseases has warned that prematurely lifting the indoor mask mandate could be fatal for high-risk groups.

At a regular press briefing on Monday, Jung Ki-suck said no one would tolerate the upsurge in serious cases or deaths that would surely result from lifting the indoor mandate amid an uptick in COVID-19 cases.

Asking who would take responsibility, the chief adviser said the matter should be carefully addressed, noting that the current rise in seasonal influenza cases further supports the case against lifting the mandate.

He said the vaccination rate with bivalent boosters should increase to 50 percent among senior citizens aged 60 and older, and over 60 percent among patients and workers at high-risk facilities before there is any discussion on lifting the mandate.

Earlier, the municipal governments of Daejeon and South Chungcheong Province had independently suggested lifting mask-wearing requirements.