The Korea University Guro Hospital in Seoul is found to have administered COVID-19 vaccines that were closely approaching or had past their recommended shelf life to around 140 people.

According to health authorities, the incident took place at the hospital using the Pfizer vaccine on August 26 and 27.

Some of those vaccinated had reported side effects and are known to be undergoing tests at emergency rooms.

The Korea Disease Control and Prevention Agency is reviewing whether the recipients of the problematic jabs should receive shots again as the vaccines will likely not have the intended effect.

In a late night text message Friday, the Guro Hospital alerted those who had been vaccinated, saying there is no safety concern but strong immunity may not develop and authorities will determine whether they need to get another shot. 

The Guro district's public health center said the hospital realized what had happened on Friday and reported the matter to the center at 5 p.m.

One hospital official said they are waiting a decision by health authorities and promised to take follow-up measures and make sure such an incident never happens again through thorough inspections and staff education.