Public fears are growing about the safety of free flu vaccines as three people have died right after getting their shots over the past five days.
According to the Korea Disease Control and Prevention Agency on Tuesday, a 78-year-old woman in Gochang, North Jeolla Province was found dead Tuesday after being given her free flu jab the previous day and an 82-year-old man in Daejeon was also found dead Tuesday five hours after getting a flu shot.
On Wednesday morning two more deaths were reported -- a man in his 60s in Jeju and a man in his 70s in Daegu died a day or two after their vaccinations.
On Oct 16, an 18-year-old high school student in Incheon died after receiving a free flu vaccine.
The causes of their death are unclear, but the agency earlier admitted that 480,000 doses of free flu vaccines supplied by Shinsung Pharm were exposed to room temperature and white particles were found floating in 610,000 commercially available doses.
The high-schooler had been injected with a vaccine from the same manufacturer but not from the compromised batches. It will take about a week to determine the cause of the victims' deaths after autopsies are completed.
Criticism of the KDCA for sitting on the news of the student's death for two days and for having kept the name of the vaccine maker from the public until Tuesday. Some 82,668 people were injected with the same flu vaccine as this student, and three of them showed allergic reactions.
Experts said it is too early to conclude that their deaths were caused by the shots.
Most deaths after vaccination are caused by anaphylaxis -- severe allergic shock -- or Guillain-Barré syndrome, a rare neurological disorder in which the body's immune system mistakenly attacks part or its peripheral nervous system.
"Anaphylaxis caused by vaccines usually occurs 15-30 minutes after injection and rarely a whole day later," said Ma Sang-hyuk of a doctors' association in South Gyeongsang Province.
Guillain-Barre syndrome, on the other hand, mostly occurs one to three weeks after vaccination, according to Kim Woo-joo at Korea University Guro Hospital. "There have been very few cases when it occurs in two days after vaccination."