SEOUL:South Korean officials refused to suspend the country's seasonal flu inoculation programme on Thursday, despite growing calls to do so following the deaths of at least 13 people who were vaccinated in recent days.

Health authorities said they have found no direct links between the deaths, which include a 17-year-old boy, and the vaccines being given under a programme to inoculate some 19 million teenagers and senior citizens for free.

"The number of deaths has increased, but our team sees low possibility that the deaths resulted from the shots," Jeong Eun-kyeong, director of the Korea Disease Control and Prevention Agency (KDCA), told parliament.

South Korea ordered 20% more flu vaccines this year to ward off what it calls a "twindemic" of people with flu developing potential COVID-19 complications, and overburdening hospitals over the winter.

"I understand and regret that people are concerned about the vaccine," Health Minister Park Neung-hoo said on Thursday, while confirming the free programme would go ahead.

"We're looking into the causes but will again thoroughly examine the entire process in which various government agencies are involved, from production to distribution," he added.

The country's free vaccine programme uses doses manufactured by local drug makers GC Pharma, SK Bioscience and Ilyang Pharmaceutical Co <007570.KS>, along with France's Sanofi <SASY.PA> and Britain's Glaxosmithkline <GSK.L>. The vaccines are distributed by local companies LG Chem Ltd <051910.KS> and Boryung Biopharma Co. Ltd., a unit of Boryung Pharm Co. Ltd. <003850.KS>.

GC Pharma, LG Chem, SK Bioscience and Boryung declined to comment. Ilyang Pharmaceutical, Sanofi and GSK did not immediately reply to requests for comment.

It was not immediately clear if any of the South Korean-manufactured vaccines were exported, or whether those supplied by Sanofi and GSK were also being used in other countries.

Kim Chong-in, leader of the main opposition People Power party, said the programme should be halted until the exact causes of the deaths had been verified.

Health authorities said on Wednesday that a preliminary investigation into six deaths found no direct connection to the vaccines. No toxic substances were found in the vaccines, and at least five of the six people investigated had underlying conditions, officials said.

EARLIER SUSPENSION

The free programme has proved controversial from its launch last month. Its start was suspended for three weeks after it was discovered that some 5 million doses, which need to be refrigerated, had been exposed to room temperature while being transported to a medical facility.

Officials said 8.3 million people had been inoculated since the programme resumed on Oct. 13, with around 350 cases of adverse reactions reported.

The government is also offering a paid vaccine programme which, combined with the free programme, aims to inoculate about 30 million of the country's 52-million population. Under the paid programme, the purchaser can select the vaccine provider from a larger pool that includes the free vaccine manufacturers plus others.

The highest number of deaths in South Korea linked to seasonal flu vaccinations was six in 2005, according to the Yonhap news agency. Officials have said it is difficult to make comparisons to previous years because of the greater numbers of people taking the vaccine this year.

Kim Myung-suk, 65, who is eligible for a free vaccine, was among a growing number of people opting to exercise choice instead.

"Though just a few people died so far, the number is growing and that makes me uneasy," she told Reuters in Seoul. "So I'm getting a shot somewhere else and will pay for it."