Health authorities have launched an investigation after a man in his 60s died in Jeju after getting an influenza shot. 

The Jeju Special Self-governing Province reported on Wednesday that the man died after receiving a free flu shot at a private clinic earlier on Monday. The time of death reported to the police was 1:17 a.m. Wednesday. 

The province’s health authorities are carrying out an epidemiological survey to determine whether there is a clear connection between the man’s death and the vaccination, while taking into account that he had underlying health problems.

The latest death marks the nation’s fourth that occurred after an influenza vaccination.