Quarantine authorities are preparing countermeasures based on the high probability of a "twindemic" situation -- the dual threat of a severe flu outbreak on top of the Covid-19 pandemic -- in the fall and winter of this year.

"There is a high possibility of simultaneous outbreaks of Covid-19 and influenza," said Im Sook-young, a senior official at the Central Disease Control Headquarters. "The government is setting up a response plan, including influenza vaccination, and plan to announce them soon."

According to the government, since the Covid-19 outbreak in early 2020, the implementation of social distancing rules and decreased face-to-face activities has allowed Korea to avoid a seasonal flu epidemic for the past two years.

Health officials have expressed concerns that the public's immunity to the influenza virus will be low, and with the Covid-19 epidemic continuing, there is a high possibility that the two infectious diseases will spread simultaneously.

"As the flu season starts during the winter, respiratory infections are more likely to spread as the season involves more indoor activities," Im said. "We have confirmed an early outbreak of the influenza pandemic in the southern hemisphere, such as Australia and New Zealand, and Korea is also closely monitoring whether an influenza outbreak will break out soon."

Health officials also expressed concerns that a winter Covid-19 resurge may come again soon as the summer resurge began earlier than expected.

"At first, we expected that a Covid-19 resurge would come in the fall and winter, but it started earlier during the summer season," Im said. "Accordingly, we believe that another viral wave will come at a later time than."

Im stressed that Korea's Covid-19 situation would remain stable for the time being.

"The current epidemic is on the decline, and if there are no big variables such as the spread of new mutations, the situation will remain stable," Im said. "This is because immunity in the population has been formed to a certain extent, and it is unlikely that there will be significant changes in the short term."

Also, as the number of severe cases and deaths, which appear two to three weeks later than the number of new confirmed cases, is currently passing its peak, the government expects that severe cases and deaths will decrease further in the future, Im added.

On Tuesday, new daily Covid-19 cases fell below 100,000, marking a moderate decline from a week ago.

The Korea Disease Control and Prevention Agency confirmed 99,837 new Covid-19 infections, including 273 from overseas, bringing the total caseload to 23,706,477.

The country reported 44 deaths, the highest since April 29, putting the death toll at 27,193, the KDCA said. The fatality rate stood at 0.12 percent. The number of critically ill patients remained high at 536, down 26 from the previous day.

Despite the virus slowdown, health officials reiterated that the public should not lower their guard, as transmission risks may rise with travel expected during the four-day Chuseok holiday starting Friday.

According to the KDCA, about 44.66 million among 52 million Koreans have been fully vaccinated. In addition, about 33.56 million people had received their first booster shots, and 7.25 million had their second booster shots.