Millions of doses of flu vaccine are under investigation following reports of improper handling, Korean health authorities said Tuesday. A subsequent delay in the vaccination schedule and possible rise in anti-vaccination sentiment may pose a major hurdle in the winter battle against a “twindemic” of influenza and novel coronavirus, experts warn.

The Korea Disease Control and Prevention Agency said in a press release Monday evening that the vaccines have been temporarily barred from being administered after reports that they were exposed to temperatures outside the safe ranges.

The amount of vaccines suspected of having been poorly managed are “some, not all” of the 5 million doses purchased with public funds for free administration, the national health agency’s chief Jung Eun-kyeong said in a Tuesday briefing. Supply of a further 7 million doses will be put on hold until the situation is sorted out, she said.

The 11 million doses not covered by the state program are unaffected. They are to be offered at prices ranging from 12,000 to 40,000 won ($10.30-$34.40) a shot.

“This may be the first instance of such problems in flu vaccine distribution in recent memory,” the agency’s director said in response to a press question.

She said the report of the inadequacies in vaccine handling has been filed by a third party. According to the laws on pharmaceutical affairs, the private subcontractor in charge could face up to a year in prison or a fine of 10 million won if violations are found.

There have been no complaints of adverse reactions among the around 118,000 people who were already administered with the flu shot, she said.

Moon Eun-hee, Food and Drug Safety Ministry director, said during the same briefing, “The possibility of the handling errors influencing the vaccine’s quality cannot be ruled out.” The vaccines in question will be discarded once an investigation reveals their safety has been compromised, she said.

Because current influenza vaccines are the inactivated kind -- as opposed to attenuated vaccines that use a weakened, live pathogen -- they may be “less vulnerable to out-of-range temperatures,” Jung of the KDCA explained.

“The cold chain, which is a temperature-controlled system of storing and transporting vaccine, should be maintained up until before the moment the vaccine is administered to a patient,” said pulmonologist Dr. Jung Ki-suck of Hallym University Sacred Heart Hospital in Anyang, Gyeonggi Province. Cold chain breaks can reduce a vaccine’s potency in protecting against the disease, at the least.

Health authorities have said the doses of flu vaccine procured in advance would be enough to cover 57 percent of the population. But stocks may run short if 5 million -- or possibly more -- go to waste. As flu vaccine supply is usually planned ahead in summer, producing more at this point was not likely to be viable.

While Korea is generally a very well-vaccinated country, people delaying or even refusing vaccination due to the latest event would also be worrisome, said Jung of the Sacred Heart Hospital.

“People at higher risk are recommended to get vaccinated before the end of October at the latest, before the flu season’s anticipated peak in November,” he said. “It takes around two weeks for antibodies to develop after the vaccination.”

Primary care physician Dr. Choi Seung-jun, based in Yongsan, central Seoul, said he started getting calls from confused parents in the morning. Out of the 19 million people eligible for the free flu vaccinations this year, children ages 13-18 were meant to get the shot starting Tuesday.

“A handful of students that came in the morning were turned away,” he said. “My concern is that some of them may forgo the shots altogether out of fear.”

Parents who have been urged to get their children vaccinated are now having second thoughts.

“I was going to take my kids to the clinic this week, for the shots. But I think I’m going to wait and see what happens,” said a mother of two middle school girls in western Seoul’s Yeouido.

Some were outraged. “Flu shots were supposed to be a big deal this year. I don’t know how they messed this up. Imagine if the vaccines were given to children and some of them had side effects,” said another parent of a high school sophomore, also in Seoul.

Such hesitancy surrounding vaccines is a public health risk, according to infectious disease specialist Dr. Kim Woo-joo of Korea University Medical Center in Guro, southern Seoul.

“If a vaccine is perceived as unreliable by the public, especially parents, children might miss the opportunity to be vaccinated and protected against preventable diseases,” he said. “Transparency from authorities is essential so that the public confidence in vaccines isn’t undermined.”

By Kim Arin (arin@heraldcorp.com)