Japan’s flu cases surge; travel warnings and treatment options take focus

February 13, 2025

“Flu” takes the spotlight

Before Korean pop, or K-pop, there was the Flower 4, or F4—a group of four wealthy, handsome, yet haughty boys from the internationally acclaimed 2001 TV series,Meteor Garden, a live-action adaptation of the Japanese manga, Boys Over Flowers (Hana Yori Dango). The iconic quartet would not be complete without the story’s heroine, Shancai, played by Taiwanese actress Barbie Hsu. More than two decades after the show first aired, Hsu has made headlines for a tragic reason—while traveling in Japan with her family this month, the actress reportedly contracted the flu and succumbed to influenza-related pneumonia within days.¹

As fans worldwide questioned the sudden turn of events, another case emerged—a Malaysian tourist who contracted the flu while visiting Japan reported facing steep hospital costs, estimated at US$3,300 per day. Unable to afford the expenses, she chose to return to Malaysia for treatment. Upon arrival, her condition had worsened, with dangerously low oxygen levels requiring urgent medical care. After five days of treatment, including multiple inhalation therapies, she was discharged.²

Japan’s biggest flu outbreak in 25 years

In late December 2024, Japan’s health authorities reported the country’s most severe influenza outbreak since record-keeping began in 1999.Between December 23 and 29, an estimated 317,812 people were diagnosed with the flu, based on data from 5,000 medical clinics nationwide. This figure is nearly three times the 104,612 cases recorded during the same period in 2023.³

With an average of 64.39 flu patients per clinic in the final week of December, Japan’s health ministry reported a nationwide increase in cases, with all 47 prefectures seeing a rise the previous week. Tokyo logged an average of 56.52 cases per clinic.⁴

H1N1 influenza, a subtype of influenza A, is a viral illness that affects the upper and sometimes lower respiratory tract. Symptoms include runny nose, chills, muscle pain, headache, fever, and loss of appetite, with some cases leading to gastrointestinal issues or lower respiratory infections. In rare instances, it can cause acute respiratory distress syndrome or secondary bacterial sepsis. A pandemic variant, known as “swine flu,” emerged from a mix of swine, avian, and human influenza strains, leading to a global outbreak that affected millions and disrupted industries like food and tourism.– National Library of Medicine

Travel warnings

This development has alerted health authorities and travelers alike. Concern continues to grow as more Asian countries urge their citizens to take precautions when traveling to Japan.

The Philippines’ Department of Health (DOH) has warned Filipino travelers to Japan about the rising flu cases. DOH’s Asec Albert Domingo attributed the surge to the winter season, noting an increase in cases as early as November 2024, with a decline expected starting January. While cases are rising, he clarified that there is no outbreak. Domingo urged travelers to take proper precautions, including handwashing, wearing face masks, covering their mouths when coughing, and resting in their hotels if they experience cough, colds, or general body weakness.⁵

In Thailand, authorities are urging tourists to reconsider travel to Japan as flu cases have surpassed 9 million over the past 144 days—an average of more than 66,000 cases per day from September 2 to January 26, according to Japan’s National Institute of Infectious Diseases.

Dr Jade Boonyawongwiroj, assistant director of Maharat Nakhon Ratchasima Hospital, advised travelers to Japan to carry anti-influenza medication like Oseltamivir. If ineffective, he said some patients may need Favipiravir, also used for Covid-19.⁶

Meanwhile, Vietnam’s Ministry of Health reported that Japan’s seasonal flu outbreak is mainly driven by influenza A, though influenza B remains a concern. To reduce infections, officials advise covering the mouth and nose when coughing or sneezing, wearing masks in crowded areas and public transport, washing hands regularly, and seeking medical care instead of self-medicating for symptoms like cough, fever, runny nose, headache, or fatigue.⁷

Vietnam has flu cases on the rise too

Vietnam is also experiencing a flu surge, with hospitals reporting a rise in severe cases requiring intensive care. Many patients suffer respiratory failure, and experts warn that the virus poses serious risks, especially for those with underlying health conditions.

According to Dr. Vo Duc Linh from the National Hospital for Tropical Diseases noted that influenza A is particularly dangerous for individuals with chronic obstructive pulmonary disease, as the virus directly affects the lungs. Those with pre-existing lung damage are more prone to severe complications.

Dr. Pham Van Phuc, Deputy Director of the hospital’s Intensive Care Center, added that people with chronic illnesses, the elderly, and those with weakened immune systems are particularly vulnerable to the flu, which can lead to severe complications such as bacterial superinfection, myocarditis, multi-organ failure, and death. Early detection and treatment can help prevent severe outcomes, and annual flu vaccinations, along with strict personal protective measures, are recommended.

Flu cases in northern Vietnam have risen due to cold weather, with the Lunar New Year heightening risks from travel and gatherings, Dr. Phuc noted. Influenza A and B are the most common strains, with flu viruses circulating year-round and causing periodic outbreaks.⁸

In a related news, in April 2024, Vietnam reported its first human case of low pathogenic avian influenza (H9N2), a different subtype from the highly pathogenic H5N1, which is causing poultry and cattle outbreaks in the U.S..⁹

H1N1 and cases spike explained

According to Japan’s Ministry of Health, Labor and Welfare, influenza A (H1N1) spreads in two ways: Droplet infection – A healthy person can become infected by inhaling the virus released through saliva or other respiratory droplets when an infected person coughs, sneezes, or spits; or through “Contact” infection-The virus can spread when an infected person touches surfaces after coughing or sneezing, and a healthy person then touches those surfaces before touching their eyes, nose, or mouth.¹⁰

Symptoms may include cough, runny nose, sudden high fever, body fatigue, headache, muscle aches, and other flu-like symptoms. As H1N1 can alter typical flu symptoms, they may vary with new cases.¹¹

Type B flu affects only humans, typically causes milder illness than type A, but can still be dangerous and does not trigger pandemics. – WebMD

Difference with conventional Influenza Strains

Since no one has immunity to H1N1, it may spread more easily than conventional flu strains, leading to higher infection rates. Preventive measures are essential to control its spread.

An influenza virus particle is about 100 nm in diameter and infects roughly 5% of Japan’s population annually. Its symptoms are harder to distinguish from the common cold. In children and the elderly, flu can lead to severe complications like pneumonia and encephalitis, with higher fatality risks for those over 65. Influenza A tends to be more severe than influenza B in adults.– TAIKO

Patients have treatment options, primarily antiviral drugs like Tamiflu and Relenza. Japan currently has a Tamiflu stockpile sufficient for approximately 33.8 million people, according to MHLW.¹²

Precautionary measures like gargling, handwashing, wearing masks, and maintaining distance may help prevent the virus’s spread. National and municipal governments provide updates on the H1N1 outbreak as needed, making it important to stay informed.

“Please do not be misled by unreliable information or rumors. Instead, seek accurate information and respond calmly without panic. Since anyone can contract Influenza A (H1N1), avoid prejudice or discrimination against those affected,” the MHLW advised.¹³