A patient waits at a hospital in Yongin, Gyeonggi Province. (Yonhap)
A patient waits at a hospital in Yongin, Gyeonggi Province. (Yonhap)

With the South Korean health authorities continuing to emphasize the importance of vaccination, especially with a higher risk of infection during the Lunar New Year holiday which begins on Jan. 25, concerns are growing over handling the flu epidemic that just reached its peak.

According to Korea Disease Control and Prevention Agency data, the recent flu outbreak saw the highest level of infected patients since 2016. The agency’s hospitalization surveillance data from 220 sample hospitals showed that 1,627 patients were hospitalized for the flu in the second week of January -- a 10.8 percent increase from 1,468 the previous week.

By age group, flu infections were most commonly observed among children aged 7 to 12, with 149.5 cases per 1,000 individuals, followed by 13 to 18-year-olds (141.5 cases), and 19 to 49-year-olds (110 cases), and children aged between 1 and 6 (83.4 cases).

While both A(H1N1)pdm09 and A(H3N2) flu strains are circulating concurrently, health authorities said such variants are closely matched to this season’s vaccines, meaning that vaccination can provide significant protection.

So is it still important to get vaccinated if the epidemic has peaked, or is it too late?

No mutations affecting antiviral resistance have been detected, but experts say getting vaccinated is still important.

“While the number of flu cases has started to decline since the peak in the first week of 2025, the activity level remains higher than in previous years. It is crucial to get vaccinated as soon as possible,” according to the KDCA official Ji Young-mi.

Experts encourage the public to follow respiratory infection prevention measures, especially with the Lunar New Year holiday around the corner. Some basic steps for prevention -- including handwashing before and after going out, practicing cough etiquette, wearing masks when feeling symptoms and ventilating indoor spaces for at least 10 minutes every two hours-- are necessary, along with vaccinations.

The country’s nationwide flu vaccination program targets high-risk groups, including children aged 6 months to 13 years, pregnant women, and seniors aged 65 and older. Designated medical institutions and public health centers offering vaccination can be found on the KDCA's vaccination helper website at nip.kdca.go.kr.

Symptoms of the latest flu epidemic include high fever, severe sore throat, cough with phlegm, fatigue and body aches.

Some say that this season's flu has become stronger, but according to Dr. Yoon-Sun Park, an infectious disease specialist at Gachon University Gil Medical Center, it is not so true.

“It’s not that the virus itself has become stronger, but the speed of flu spread has been very rapid this season. This may also be due to less awareness toward the flu in recent years due to COVID-19.”

Patients wait their turn at a hospital in Seongbuk-gu in Seoul. (Yonhap)
Patients wait their turn at a hospital in Seongbuk-gu in Seoul. (Yonhap)

Here are some other common misconceptions about the current flu outbreak:

1. Is it true that if I have had the flu already, I have antibodies and don’t need a vaccine?

No. The flu virus evolves with variations in key proteins called hemagglutinin (H) and neuraminidase (N), creating different strains. Currently, H1N1 and H3N2 (subtypes of Influenza A) are circulating. Flu vaccines are designed annually based on statistic-based predictions of prevalent strains. Even if you have already had the flu, vaccination is still necessary to protect against other strains.

Since both influenza A and B are spreading concurrently, the current quadrivalent vaccine provides immunity against four strains: two A subtypes and two B subtypes. This means that even if you’ve had one flu type, vaccination can protect you against the remaining three strains.

Health authorities recommend waiting one to two weeks after recovering from the flu before getting vaccinated.

2. Is it normal to get the flu right after vaccination because the immunity built by the vaccine caused it?

No. Doctors say flu vaccines are inactivated, meaning they are made with killed or altered pathogens. They don’t have any function to cause the flu.

Live attenuated vaccines — such as MMR, BCG or intranasal flu sprays — weaken but do not fully kill the virus. However, such vaccines rarely cause infections among healthy people. However, MMR live vaccines should not be given to pregnant women because they can harm the fetus.

3. Do I need another dose of vaccine if I catch the flu after being vaccinated?

No. If you contract the flu after vaccination and are treated with antivirals like Tamiflu (oseltamivir) or Peramivir (peramivir), there’s no need for additional vaccination.

According to doctors, flu vaccines help the body form antibodies. Antiviral treatments kill the virus, but they don’t eliminate the antibodies formed by the vaccine. Thus, no further vaccination is necessary.

This article is part of a series that delves into the health and well-being of people in South Korea, highlighting the latest developments in health care needs and the services available to meet them. -- Ed.