South Korean health authorities have put on hold the free influenza vaccination program.
The main batch of vaccinations was scheduled to start this Tuesday, but there were problems with the refrigeration of the batch of vaccines for the 13 to 18 age group.
The Korea Disease Control and Prevention Agency has immediately stopped all flu shots and held a briefing to explain the situation.
"There was a problem with the refrigeration temperature during the distribution. There's no problem with the vaccine. All the vaccines have passed the Ministry of Food and Drug Safety's tests, and we are starting an investigation about the distribution process."
The KDCA said that the vaccination distributed earlier this month for children under the age of nine is deemed safe.
Health authorities are working on providing free vaccinations to some 19 million people 37 percent of the country's population to prevent a double outbreak of flu and COVID-19, dubbed a "twindemic".
The free flu shot is available for children aged between 6 months and 18 years, pregnant women and those aged 62 and above.
Jang Tae-hyun, Arirang News.