Korea sees rise in influenza B cases amid flu epidemic

A 39-year-old office worker surnamed Kim said he was recently diagnosed with influenza B virus and suffered from a high fever of 38 degrees Celsius (100.4 degrees Fahrenheit) and severe coughing.

Patients and their caretakers wait for their turn in the waiting room to see a doctor at a hospital in Seoul on Tuesday. [NEWS1]

Influenza B is on the rise in Korea as influenza A sweeps the country.

A 39-year-old office worker surnamed Kim said he was recently diagnosed with influenza B virus and suffered from a high fever of 38 degrees Celsius (100.4 degrees Fahrenheit) and severe coughing.

"When my family contracted influenza A, nothing happened to me. Eventually, I [was diagnosed with] influenza B," Kim said.

Amid the soaring cases of influenza A, reaching a five-year peak, Korea is also reporting more cases of influenza B.

"Influenza A cases [have been] prevalent, but [now], a dual diagnosis of influenza A and B is common," a doctor who runs a clinic said.

"Some patients get influenza B after recovering from influenza A," he added.

A mother, surnamed Park, whose nine-year-old son had influenza A in October and influenza B recently, said, "My son got well a day after taking [peramivir] when he had influenza A."

"This time, with influenza B, his fever just a momentarily dropped to 37.7 degrees Celsius and rebounded back to 38.5 and 39 degrees Celsius even after receiving intravenous therapy."

"Some said influenza B has lighter symptoms than type A, but [in this case] I think it's not," Park added.

On the internet, some say that they suffered from influenza A and B in a two-week interval.

A baby gets a flu shot at a pediatrics clinic in Seoul on Dec. 7. [NEWS1]

There are three types of flu viruses: A, B and C.

Type A is associated with the winter season, usually spreading in December. Then, influenza B follows typically in spring, mostly in March or April.

The recent epidemic is mainly led by influenza A but also accompanied by influenza B, resulting in a growing number of patients.

According to the Korea Disease Control and Prevention Agency, in the second week of December, 42.2 percent of those tested for the flu tested positive. By virus type, 35.2 percent tested positive for influenza A, while seven percent tested positive for influenza B.

In 2019, the number was 4.2 percent for influenza B for the same time period.

"Different infectious diseases mingled up together after the Covid-19 pandemic," Lee Young-seok, a professor of respiratory conditions and critical care at Korea University Guro Hospital, said.

"While the type A influenza virus is the leading actor, influenza B cases are detected occasionally. No one is immune from influenza even after recovery. If the virus type alters, the person can catch the flu again."

"The person sick with the flu has trouble in their immune system. It means that they can have reinfection."

A man waits to receive a free flu shot at a hospital in Gwanak District in southern Seoul in October. [YONHAP]

Medical professionals noted the importance of getting vaccinated as the flu epidemic can continue until spring next year. They added patients should seek and accept medical treatment as soon as possible.

"As there were fewer flu cases over the last three years, [when people maintained strong quarantine measures] the flu antigens that people used to possess are a bit deteriorated. This triggered heavier and serious symptoms [that are seen today]," Lee added.

"When flu causes acute respiratory distress syndrome or makes people have difficulty breathing, patients might need to rely on extracorporeal membrane oxygenation, a medical device providing oxygen to cure their respiratory failure. At worst, it can lead to death."

"For any person older than 65 or with illnesses such as diabetes, vaccination is mandatory [as a cautionary measure.] Thankfully, there are medications for cure with no reported tolerance of the substances. Patients should take medicine or have an injection within 48 hours after their symptoms appear," he said.

"One-third of hospitalized patients [at the department] are flu patients," Chon Eun-mi, a professor and director of the respiratory center at Ewha Womans University Mokdong Hospital, said.

"Any older adult patients, even those vaccinated, should take medical treatment when they have symptoms. It would be wiser to see doctors if their symptoms last after the treatment because it could develop into pneumonia complications."

BY HWANG SU-YEON [lee.soojung1@joongang.co.kr]