Symptoms and Serious Complications of Seasonal Influenza

Seasonal flu, caused by influenza A or B viruses, tends to spike in the winter months and can range from mild to severe. In some cases, it may lead to dangerous complications such as pneumonia or respiratory failure.

Common symptoms include high fever, cough, headache, muscle aches, and fatigue. Older adults, young children, pregnant women, and individuals with chronic illnesses are especially vulnerable to severe illness.

Annual flu vaccination remains the most effective method of prevention. Read on to learn more about influenza and how to stay protected with insights from H PLUS International Medical Center.

What is seasonal influenza?

Seasonal flu is a contagious respiratory illness caused by influenza viruses that spread from person to person and reappear every year. It primarily affects the nose, throat, and lungs, and often peaks during the winter months due to several contributing factors.

• Enclosed environments: People tend to stay indoors with less ventilation during cold seasons, increasing the risk of airborne transmission.
• Weakened immunity: Reduced sunlight exposure lowers vitamin D and melatonin levels, weakening immune defense mechanisms.
• Ideal conditions for viruses: Influenza viruses survive longer and spread more easily in cold, dry air, leading to a higher rate of infection.

Understanding how the flu spreads and its seasonal patterns can help you take proactive steps to protect your health during peak months.

Who is at higher risk of flu complications?

Anyone can catch the flu—even those in good health. However, certain groups are at greater risk of developing severe complications, including:

• Adults aged 65 and older: Weakened immunity makes them more prone to pneumonia and respiratory failure
• People with compromised immune systems: Such as individuals with HIV/AIDS or cancer
• Patients with chronic diseases: Conditions like asthma, diabetes, or heart disease may worsen with flu infection
• Pregnant women: Changes in immune function and physiology increase risks for both mother and baby
• Children under 5, especially under 2 years old: Immature immune systems make them more vulnerable to serious respiratory illnesses

Flu vaccination is the best protection for these high-risk groups and should be prioritized annually.

What are the symptoms of seasonal flu?

Seasonal influenza can range in severity and may cause complications if left untreated. Unlike the common cold, the flu often strikes suddenly with multiple symptoms, including:

• High fever or chills
• Persistent cough, sore throat
• Runny or congested nose
• Muscle aches and prolonged fatigue
• Headaches and dizziness
• Vomiting or diarrhea (more common in children)

Because many flu symptoms overlap with other respiratory illnesses, it is important to seek medical advice for accurate diagnosis and timely treatment if flu is suspected.

Serious complications of seasonal flu

Most flu cases resolve within a few days to under two weeks. However, in certain cases, influenza may cause life-threatening complications such as:

• Mild to moderate complications: Ear infections, sinus infections caused by the flu virus
• Severe complications: Pneumonia due to the flu virus alone or combined with bacterial infections; inflammation of the heart (myocarditis), brain (encephalitis), muscles (myositis), and breakdown of muscle tissue (rhabdomyolysis); and sepsis, a life-threatening condition triggered by extreme inflammation
• Worsening of chronic conditions: Flu may aggravate existing medical conditions. People with asthma may experience severe attacks, while those with heart conditions may face dangerous circulatory issues

How to effectively prevent seasonal flu

Annual flu vaccination remains the most reliable way to protect yourself against influenza. The World Health Organization (WHO) recommends vaccination especially for:

• Pregnant women
• Children aged 6 months to 5 years
• Adults over 65
• People with chronic conditions
• Healthcare workers

In addition to vaccination, individual hygiene and preventive practices are essential:

• Wash hands regularly with soap and dry thoroughly
• Cover your mouth and nose with a tissue or your elbow when coughing or sneezing; discard tissues properly
• Isolate yourself if experiencing flu-like symptoms to prevent spreading illness
• Avoid close contact with sick individuals
• Refrain from touching your eyes, nose, or mouth to reduce the chance of virus entry

Protecting your health also helps reduce the spread of infection in the community.

Where to get quality flu care and vaccination

H PLUS International Medical Center offers comprehensive vaccination services, including a full range of flu vaccines to protect individuals of all ages. Each patient undergoes a pre-vaccination screening by experienced doctors, ensuring safe and tailored immunization plans in line with the latest guidelines from the Ministry of Health and WHO.

Our Korean and Vietnamese medical teams are not only highly skilled but also deeply committed to patient care. After vaccination, clients are monitored for 30 minutes to ensure safety and receive detailed guidance on post-vaccination care, including pain management methods suitable for children.

H PLUS maintains a GSP-compliant cold chain system for optimal vaccine storage. Our vaccination center is spacious, well-ventilated, and equipped with a pediatric clinic and a kid-friendly waiting area to keep children relaxed during their visit.

Parents will also receive timely reminders for their child’s next scheduled dose, and all vaccination records are automatically integrated with the National Immunization Database for easy tracking.

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Phòng khám Đa khoa Quốc tế H PLUS | H PLUS International Medical Center
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