This year’s flu season has arrived with unusual intensity; however, many people are mistaking severe infections for a common cold, leading to delays in treatment.

On the “Health 1+1” program, Peng Tzu Liu, deputy director of the Health Management Center at Taiwan’s Shin Kong Wu Ho-Su Memorial Hospital, discussed key warning signs that necessitate prompt medical attention, preventive measures for high-risk groups, and protective strategies for travelers.

The influenza virus mutates almost every year, Liu noted. Based on his clinical observations and experience, this year’s flu season differs from previous ones, with an earlier-than-usual outbreak.

Flu cases typically start rising in November, as large gatherings and holiday celebrations toward the end of the year facilitate virus spread and increase the risk of mutations. As a result, flu activity usually peaks between January and February before gradually declining by late March or early April.

However, this year, cases began increasing as early as October, coinciding with the rollout of the flu vaccination campaign—indicating an early outbreak.

Common Flu Symptoms

Influenza typically causes the following symptoms, Liu said:

• High Fever: Most patients develop a high fever, with body temperature ranging from 101 to 102°F (38.5 to 39°C).


• Respiratory Symptoms: Common respiratory issues include sore throat, cough, and runny nose. In severe cases, a lower respiratory tract infection may develop, leading to increased coughing and phlegm production.


• Gastrointestinal Symptoms: Some patients may experience gastrointestinal issues, including vomiting and diarrhea.


• Muscle Aches: Muscle pain from the flu is typically more severe than that of a common cold.

Warning Signs of Severe Flu

Liu cautioned against equating the following warning signs with a common cold. If you experience any of these symptoms after contracting the flu, seek medical attention immediately:

• Persistent High Fever: A high fever lasting more than two days.


• Severe Respiratory Symptoms: Possible signs include low blood oxygen, difficulty breathing, or, in patients with chronic lung disease, rapid breathing, chest tightness, and chest pain.


• Persistent Vomiting: This could indicate severe gastrointestinal symptoms leading to dehydration or, in some cases, a sign of inflammation of the brain.


• Altered Consciousness: Symptoms may include confusion, drowsiness, or changes in mental status.


• Seizures or Convulsions: These could suggest potential central nervous system impairment.


• Low Blood Oxygen Levels: Readings below 94 percent indicate insufficient oxygen supply.

High-Risk Groups

People with the following conditions are at higher risk for severe flu complications, according to Liu:

• Cardiovascular or cerebrovascular diseases.


• Chronic diseases affecting major organs, such as liver cirrhosis, kidney failure requiring dialysis, or chronic obstructive pulmonary disease (COPD).


• Asthma.


• Central nervous system disorders, such as epilepsy, brain tumors, or other neurological conditions.


• Overweight or underweight.


• Cancer

People with weakened immune systems, including chronic heavy alcohol users, diabetics, those taking immunosuppressive medications, as well as infants, young children, and older adults are also at risk.

Each year, multiple strains of the influenza virus circulate, but the flu vaccine is formulated to target only those strains that surveillance data indicate are most likely to spread, Liu noted. As a result, it is still possible to contract a strain not covered by that season’s vaccine.

For high-risk groups, Liu recommends getting vaccinated annually. The primary goal of vaccination is not to completely prevent infection but to reduce the risk of severe illness.

The current quadrivalent influenza vaccine, designed to protect against two strains of influenza A and two strains of influenza B, has been shown to reduce the severity and spread of flu infections.

Severe Flu and the Risk of Cytokine Storm

Liu highlighted the case of Taiwanese actress Barbie Hsu, 48, who died from flu-induced pneumonia while traveling in Japan. Analyzing her situation, Liu noted potential factors that may have contributed to the severity of her illness.

Hsu had a history of mitral valve prolapse, a condition where the mitral valve doesn’t close perfectly, asthma, and epilepsy. She had also been hospitalized in the past after a fever-triggered epileptic seizure. Given these underlying conditions, she was considered high-risk, making her more susceptible to flu complications.

Liu stated that Hsu’s illness progressed rapidly, potentially due to a cytokine storm—an excessive immune response. She developed “white lung” pneumonia, a condition marked by severe lung inflammation, and was later diagnosed with sepsis, indicating that her body had entered a state of excessive immune response.

A cytokine storm occurs when the immune system overreacts, attacking both the virus and the host, leading to widespread inflammation and organ damage.  This phenomenon is sometimes seen in younger adults, where a highly aggressive infection causes sudden and rapid deterioration.

Liu cautioned that severe flu is not just a result of weak immunity—in some cases, an overactive immune response can damage vital organs, increasing the risk of life-threatening complications.

Should You Travel If You Have Flu Symptoms?

If you develop flu symptoms before a trip—whether for leisure or business—should you cancel your plans? Liu offers the following advice:

• Evaluate Your Symptoms: If you are unsure about their severity, consult a doctor to assess whether it is safe to travel.


• Mild Symptoms: If you lack a persistent high fever, severe respiratory issues, or gastrointestinal symptoms and feel well overall, you may proceed with your trip after obtaining medical advice and the appropriate medications.


• Don’t Self-Prescribe: For proper treatment, it is best to follow a doctor’s guidance, as the need and timing of certain medications may depend on the severity of your condition.

Managing a Flu Infection While Traveling

For travelers concerned about contracting the flu during a trip, Liu recommends the following precautions:

• Bring Necessary Medications: Inform your doctor about travel plans to ensure you have sufficient medication for your trip.


• Discuss Your Destination: Talk about potential health risks related to your travel location with your doctor. If risks are low, they may prescribe medications for symptom management.


• Carry Cold Medicine. Basic cold relief medications can be purchased from a pharmacy to manage mild symptoms.


• Don’t Self-Medicate: Antibiotics or antiviral drugs should only be taken under a doctor’s guidance.


• Seek Help If Symptoms Worsen. If you develop severe flu symptoms while traveling, do not delay seeking medical care.


• Consider Travel Insurance. To avoid unexpected medical expenses, purchase travel insurance prior to departure and keep medical documentation for potential claims.