Currently, three drugs are licensed for influenza treatment in Korea: Tamiflu (oseltamivir), a five-day oral medication; Xofluza (baloxavir marboxil), a single oral dose; and Peramiflu (peramivir), a single intravenous administration.

Ironically, the most sought-after flu treatment in Korea this year is an IV therapy based on peramivir. This raises the question: why has a treatment requiring a 15-minute intravenous needle insertion gained more traction than a convenient pill?

One primary reason is the severity of this year's influenza epidemic in Korea.

Speaking on the YouTube channel “I am a doctor,” Professor Lee Jae-gap, an infectious disease specialist at Hallym University Kangnam Sacred Heart Hospital, noted that "(Flu patients) are so tired that they can't even go to the pharmacy to get their medication," highlighting the epidemic's intensity as a factor driving the popularity of hospital-administered IV fluids in Korea.

Another contributing factor is a distinct cultural preference among Koreans for injectable flu medications. "Koreans have a strong preference for injections," Professor Lee said.

Tamiflu is covered by insurance, so the price is much lower at 10,000 won ($7.3). But the injection costs more than 100,000 won, and other pills cost 80,000 to 100,000 won, which is almost 10 times the cost of Tamiflu. People say they can’t take Tamiflu for five days. When asked to choose between injections and pills, 70 percent of patients in Korea choose injections, Lee pointed out.

So, does an IV flu shot provide the best symptom relief compared to Tamiflu, which lasts five days, or Xofluza, which is a single shot? Not necessarily.

“A single shot is about the same or slightly better than five days of Tamiflu,” Lee says. He explained that a single pill is about the same or slightly better than five days of Tamiflu, but the three drugs are about the same in reducing symptoms.

Some clinical studies have shown that a single dose is better at reducing the flu virus or blocking transmission or that the other two drugs work faster than Tamiflu in terms of treatment, but it's hard to tell.

“Regarding the effectiveness of reducing the virus and blocking transmission, a single dose is the best so far,” Professor Lee said. “In clinical studies, there are phase 3 results that show that a single injection or oral medication is a little faster, but it is not measured accurately.”

Can nutritional fluids help people with the flu? They are not effective for all flu patients.

“There are some patients, especially among older adults, who have a very high fever and lose a lot of appetite and can't eat for two to three days or more. For these patients, IV nutritional fluids can be helpful for the duration of the illness, but it is not a routine medical practice,” Lee said.