Public concern over the safety of flu shots has grown in South Korea as the authorities reported 36 cases of death after vaccination as at 1pm yesterday, putting strain on efforts to curb a potential "twindemic" of winter flu and the coronavirus.
The country is still grappling with Covid-19, reporting 155 cases yesterday - the highest since Sept 11 and the second day in a row with case numbers in the triple digits.
This brings the total to 25,698.
The health authorities now also have to tackle a deepening fear of the state-administered free flu vaccine programme after two batches of vaccine were found faulty.
South Korea hopes to inoculate some 19 million people for free, especially vulnerable groups such as young children and the elderly, ahead of the annual flu season next month, when temperatures drop.
No causal link has been found yet between the flu shots and the fatalities so far, and investigations are under way to determine the exact cause of the deaths.
It remains unknown how a 17-year-old living in Incheon, the first case, died on Oct 16, two days after getting a free flu shot.
South Korea's forensic agency said it has found no direct link between his death and the flu shot.
But the number of similar deaths has since spiked, with 18 alone reported on Thursday. Most of the deaths involved elderly people with underlying medical conditions.
A woman in her 80s living in the southern port city of Busan died yesterday after being taken to the hospital for breathing difficulties. She had been given a flu shot at another hospital four days ago.
The police said she probably died of cardiovascular issues, but an autopsy will be performed to confirm if her death is related to the flu shot.
Seoul has reported at least four such deaths, including a 53-year-old woman who developed breathing difficulties and died on Wednesday, four days after getting vaccinated.
According to the Korea Disease Control and Prevention Agency (KDCA), vaccines manufactured by at least six of 10 companies enrolled in the government programme are linked to such deaths - SK Biopharmaceuticals, Shinsung Pharm, Korea Vaccine, Boryung Pharm, LG Chem and GC Pharma.
Two batches of flu vaccine have been found faulty - one by Shinsung Pharm that was wrongly stored at room temperature last month instead of being refrigerated, the other by Korea Vaccine that was found to contain white particles earlier this month.
The news sent jitters across the country, putting an end to queues for vaccinations. Still, the health authorities are pushing ahead with the nationwide vaccine programme.
KDCA commissioner Jeong Eun-kyeong said at a Parliament hearing on Thursday that experts agreed "the deaths do not appear to be caused by vaccine products or issues with toxicity".
She added that an inquiry into a possible causal relationship will take at least two weeks.
The Korean Medical Association has recommended postponing the vaccine programme for a week while awaiting the probe's results.
As at Sunday, 9.55 million people have received flu shots, according to the KDCA. About half were sponsored by the government.
Teacher Park Myong-sook, 58, is worried about possible side effects after getting her flu shot.
"People get flu shots to live, but it is now killing us," she told The Straits Times.