South Korea's health authorities on Sunday slightly revised down the number of people who have been injected with flu vaccines that may have been exposed to room temperature, after local governments provided confirmed data.

The Korea Disease Control and Prevention Agency (KDCA) had reported that 2,303 people received the potentially defective flu vaccines as of last Friday, but the number was revised down to 2,295.

The number "slightly declined because some local governments corrected the data," the KDCA said.

The number of people who have reported abnormal reactions, such as a fever and chills, stood at 12, unchanged from the previous day.

Last month, the KDCA temporarily halted its plan to offer free seasonal flu shots after some of about 5.78 million doses of flu vaccines were partially exposed to temperatures outside the storage range.

South Korea has planned to preemptively offer free flu shots to prevent people from potentially being infected with both the flu and the new coronavirus.

The KDCA has checked the 5.78 million doses of flu vaccines, and the quality inspection is expected to end early next week.

The KDCA said it will announce plans to offer free flu shots when the inspection is over. 

Inactivated vaccines should be stored in a refrigerator, and exposure to room temperature could result in decreased vaccine potency and increased risk of vaccine-preventable diseases.

But the safety of those vaccines exposed to room temperature has yet to be determined. (Yonhap)