[Sportschosun, Jang Jong-ho] The Korea Disease Control and Prevention Agency (KDCA) issued an influenza epidemic advisory for the 2026–2027 season on the 11th. It was the earliest issuance date among the seasonal records released by the KDCA, coming 36 days earlier than the previous season’s advisory on October 17, 2025.
Children are driving this outbreak. In the first week of September (week 36), the number of influenza-like illness patients per 1,000 outpatients was 75.1 among children aged 7–12, 49.8 among those aged 1–6, and 31.3 among those aged 13–18—up to 8.5 times the figure of 8.8 among people aged 65 and older.
The Korean Association of Pediatric Hospitals said, "The question caregivers ask most often in the examination room is, 'Is this a cold, influenza, or COVID-19?' But there is another question that is actually more important," adding, "We first need to clear up misunderstandings about why people get vaccinated."
The article reviews influenza through a Q&A with Choi Yong-jae, president of the Korean Association of Pediatric Hospitals.
-What is the current outbreak situation?
▶It is not mild. In the first week of September, the number of influenza-like illness patients was 25.3 per 1,000 outpatients, about twice the seasonal epidemic threshold of 12.9. There were 300 hospitalized patients at hospital-level facilities, about 13 times the 23 recorded during the same period of the previous season. The influenza detection rate in testing also rose from 2.3% during the same week last year to 16.3%. The virus currently circulating is essentially a single strain, the influenza A(H1N1)pdm09 virus. There is also some good news. The KDCA said the virus is similar to the strain included in this season’s vaccine and that no resistance mutations against antiviral treatments have been identified. This means conditions are in place for both vaccines and treatments to do their jobs.
-What is the difference between a cold, influenza, and COVID-19?
▶The biggest difference is how they begin. A cold usually starts gradually over several days with a runny or stuffy nose and a sore throat, while fever is absent or not high. The child generally continues to play and eat. Influenza begins suddenly at a certain point. It can cause a high fever of around 39°C, chills, severe headache and muscle aches, along with the observation that "the child becomes very lethargic." Children may also commonly experience abdominal pain, vomiting, and diarrhea. The younger the child, the more likely the illness is to appear only as fussiness and lethargy because the child cannot describe the symptoms. With currently circulating COVID-19 variants, symptoms often resemble those of a cold, including fever, sore throat, and cough.
-Can they be distinguished based on symptoms alone?
▶The three cannot be reliably distinguished by symptoms alone. Influenza can begin like a cold, and cold viruses can also cause a high fever. In addition, several respiratory viruses are circulating during this season, including parainfluenza virus, rhinovirus, human metapneumovirus (hMPV), and respiratory syncytial virus (RSV).
Caregivers do not need to identify the exact disease themselves. They should monitor the child’s breathing, level of consciousness, fluid intake, and urination. The diagnosis can be confirmed through testing at a medical facility.
-They say it is a "twindemic." Is COVID-19 spreading at the same time?
▶Strictly speaking, influenza is the main concern right now.
The number of COVID-19 inpatients did rise to 193 in the first week of September. However, that is still lower than the 433 recorded during the same period last year, and 65.3% of the patients were aged 65 or older. "Twindemic" is a media expression, not an official term used by the KDCA. The association believes it is more accurate to say, "Influenza is surging among children, while COVID-19 is increasing mainly among older adults," rather than saying that "the two diseases are exploding at the same time." Anxiety should be reduced through accurate information.
-Does getting an influenza vaccine prevent influenza?
▶No. This is the most dangerous misunderstanding. The purpose of influenza vaccination is not to prevent every infection but to prevent the illness from becoming severe. The KDCA also stated in its annual national influenza report, "The World Health Organization says that the purpose of influenza vaccination is to prevent severe illness and death among high-risk groups."
Domestic big-data analyses show this clearly, based on all age groups. The effectiveness of preventing infection itself was 10.2–41.4%, preventing hospitalization was 4.0–39.2%, preventing progression to severe illness was 63.7–74.6%, and preventing death was 52.2–81.1%.
Therefore, a vaccine is closer to a "safety device against the worst" than a "shield against infection."
-Is influenza really that dangerous? Doesn’t it usually go away after a few days?
▶For most people, it does. But the association is concerned not about the majority, but about what lies outside it.
The influenza complications listed by the KDCA include not only otitis media and bacterial pneumonia, but also myocarditis, pericarditis, encephalitis, encephalopathy, transverse myelitis, rhabdomyolysis, and Reye’s syndrome.
A study analyzing 1,988 children hospitalized with influenza at three university hospitals in South Korea found neurological complications in 8.1% of them, or 161 children. Most cases were febrile seizures, and 96% recovered completely. However, three children died; the causes of death were myocarditis, encephalopathy, and concurrent encephalitis and myocarditis, respectively.
Influenza-associated encephalopathy and encephalitis in Korean children are reported less frequently than in Japan and other countries, and the prognosis is relatively favorable. However, rare does not mean nonexistent. In the same study, children with underlying neurological disorders faced a 5.4-fold higher risk, and those aged 6 months to 6 years were the most vulnerable.
Overseas data paint a more serious picture. Among children who died of influenza in the United States, encephalopathy and encephalitis accounted for 18% of complications, while myocarditis and cardiomyopathy accounted for 13%. Moreover, 44% of the children who died had no underlying medical conditions. This is why it is not enough to say, "My child is healthy, so everything will be fine."
-My child was vaccinated last year but still got influenza. Doesn’t that mean the vaccine is not very effective?
▶"Getting infected" and "nearly dying" are different outcomes. According to domestic statistics, a study of 1,389 Korean children during the 2009 H1N1 pandemic found that all 23 children with neurological involvement, including encephalopathy, had not been vaccinated.
A pediatric study conducted in intensive care units at 17 U.S. hospitals found that, among the same children, vaccination was 75% effective at preventing life-threatening severe influenza—higher than its effectiveness of 57% in less severe cases. In other words, the more serious the illness, the better the vaccine protected against it.
Data on U.S. children across five influenza seasons showed that, even among children confirmed to have influenza, those who had not been vaccinated had longer hospital stays and longer stays in intensive care. There is also a decisive figure: among U.S. children who died of influenza during the 2024–2025 season, 89% had no documented vaccination history. Among children who died of influenza-associated encephalopathy, only 20% had been vaccinated.
-When should children be vaccinated, and who should receive the shot?
▶The eligibility age for free vaccination of children has been extended by one year this season.
Children aged 6 months to 14 years—those born from January 1, 2012, through August 31, 2026—are eligible for free vaccination. The program has been expanded from age 13 last season to include children through the second year of middle school.
Vaccination will begin on the 21st for children requiring two doses and pregnant women, among others. Children requiring one dose will become eligible on the 28th.
Two-dose recipients are children aged 6 months to under 9 years who have never been vaccinated or have received only one dose. Vaccinations are available at approximately 23,000 designated medical institutions nationwide and public health centers, regardless of address.
Children eligible for two doses must not stop after receiving only one. In a U.S. intensive care unit study, no protective effect was observed when children who needed two doses received only one. It is more accurate to understand that the child does not gain the effect by simply receiving one additional shot; two doses are needed to achieve the intended protection.
-My child has influenza. When can they return to school or daycare?
▶The standard is "24 hours after the fever has subsided." The KDCA recommends that children diagnosed with influenza stay home from school or daycare until 24 hours after their fever has gone down and they are no longer infectious. If fever-reducing medication was used, caregivers should wait 48 hours from the time of the last dose. A fever lowered by medication does not mean the fever has truly subsided. During the epidemic advisory period, health insurance also covers antiviral prescriptions for high-risk groups, including children, based on a doctor’s judgment even without testing. Antivirals work best when taken early in the illness, so medical care should not be delayed.
-When should a child go to the hospital immediately?
▶A child should be taken to a medical facility without delay if any of the following applies: ▲shortness of breath or visible pulling in of the chest or spaces between the ribs; ▲marked lethargy, difficulty waking, or responses that differ from usual; ▲seizures or changes in consciousness, such as incoherent speech or unusual behavior; ▲inability to drink much and a clear decrease in urination; ▲pale or bluish lips or face; ▲a fever that returns after subsiding, accompanied by worsening cough or breathing difficulty; ▲fever in an infant younger than 3 months; or ▲influenza-like symptoms in a high-risk child with chronic heart or lung disease, neurological disease, immunosuppression, or a similar condition.
Choi Yong-jae, president of the Korean Association of Pediatric Hospitals and director of Uijeongbu Ttunteun Children’s Hospital, said, "When we recommend influenza vaccination, people respond, 'But my child got it even after being vaccinated.'" He added, "That statement is not wrong. The misunderstanding is about what the vaccine is designed to do."
He continued, "The purpose of influenza vaccination is not to prevent infection altogether. It is to prevent death and keep the illness from progressing to severe complications such as myocarditis or encephalopathy." He emphasized, "Domestic statistics also show that the effect of preventing severe illness and death is much greater than the effect of preventing infection. A vaccine is not an umbrella that keeps influenza away; it is more like a seat belt that protects against the worst."
Choi also urged, "Nearly half of the children who died of influenza had been healthy, with no underlying disease. That is the hardest situation to endure in clinical practice." He added, "The outbreak began more than a month earlier than usual. Vaccinations begin on September 21, so please check your child’s vaccination schedule today. In particular, make sure that children who need two doses do not receive only one and stop there."
Jang Jong-ho, bellho@sportschosun.com
This article has been translated by GripLabs Mingo AI.
