Some seasonal flu vaccines that were mishandled during storage were found to have been used for inoculation, health authorities said Friday.  

The Korea Disease Control and Prevention Agency (KDCA) said some of the bottles shipped by Shinsung Pharm. Co. were used in late September in neighborhood clinics as part a nationwide flu vaccination program.  

The program was temporarily halted on Sept. 22 after some of the inactivated vaccines shipped by the company were exposed to room temperature during shipping, stoking concerns over decreased vaccine potency and safety. The authorities later concluded there is no safety issue.  

The KDCA said it is currently looking into the exact number of bottles that were used and the number of people who had received the shots.  

Around 5 million doses shipped by the company were discarded.  

The country has been pushing for a free state flu shot scheme to inoculate around 19 million people, including teenagers and senior citizens.  

The free vaccination program was expanded this year in an effort to prevent the potential "twindemic" of COVID-19 and flu during winter.  

Health authorities have repeatedly urged people to take flu shots, citing there is no safety issue, before the influenza season arrives, as more deaths could occur from serious complications triggered by the flu, such as pneumonia.  

Generally, the flu season arrives between end-November and December. Considering that flu vaccines cause antibodies to develop in the body about two weeks after vaccination, experts here recommend people get flu shots by mid-November. (Yonhap)