Have you ever experienced the debilitating symptoms of influenza? The high fever, body aches, and extreme fatigue that make even the simplest tasks seem impossible? Influenza, commonly known as the flu, is a highly contagious respiratory illness caused by the influenza viruses. It can affect people of all ages, but certain groups, such as the elderly, young children, and individuals with compromised immune systems, are more susceptible to severe complications. In recent years, influenza has become a global concern, with various strains causing widespread outbreaks.


What is Influenza?

Influenza is caused by the influenza viruses, a family of viruses that primarily affects the respiratory system. The virus spreads through respiratory droplets when an infected person coughs, sneezes, or talks. It can also be contracted by touching surfaces contaminated with the virus and then touching the nose, mouth, or eyes. Once the influenza virus enters the body, it targets the respiratory tract, specifically the nose, throat, and lungs. This leads to inflammation and the characteristic symptoms of the flu.

The symptoms of influenza can vary from mild to severe. Common symptoms include sudden onset of fever/chills, muscle or body aches, fatigue, cough, sore throat, runny or stuffy nose, and headaches. In some cases, people may also experience vomiting and diarrhea, although these symptoms are more common in children than adults.

One of the reasons influenza is so challenging to control is its ability to mutate. Each year, new strains of the virus emerge, escaping from the immune system’s memory. New flu vaccines are produced each year based on the global surveillance of circulating influenza virus at the end of previous season.

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Several treatment options can help alleviate symptoms and reduce the duration of illness.

  • Over-the-counter pain relievers, such as acetaminophen or ibuprofen, can help reduce fever and relieve body aches.
  • Antiviral medications, such as oseltamivir (Tamiflu) or zanamivir (Relenza), may be prescribed by a healthcare provider for individuals at high risk of complications or those with severe symptoms.
  • Keep hydrated and ensure adequate rest.

Early treatment with antiviral medications ( < 48 hours after symptoms onset) can help shorten the duration of illness and reduce the risk of complications e.g. pneumonia.


Preventive Measures and Seasonal Influenza Vaccine

Prevention is key when it comes to influenza. Practicing good hygiene (especially before and after touching the mouth, nose or eyes) such as washing hands frequently with soap and water, using hand sanitizers, and covering your mouth and nose when coughing or sneezing, can significantly reduce the risk of infection.

Seasonal Influenza Vaccination is one of the effective means in preventing influenza and its complications together with reduction in influenza-associated hospitalisation and death.

There are 3 types of registered Seasonal Influenza Vaccines in Hong Kong.

  1. Inactivated influenza vaccines (IIV)
  2. Live attenuated influenza vaccine (LAIV) (nasal spray)
  3. Recombinant influenza vaccine (RIV).


Of these vaccines, there are two further types, providing different protections against the virus. The trivalent vaccine protects against three strains of influenza (two influenza A strains and one influenza B strain), while the quadrivalent vaccine protects against an additional influenza B strain.

Who can receive the influenza vaccine? The Centers for Disease Control and Prevention (CDC) recommends that everyone aged six months and older to receive an annual influenza vaccination, with rare exceptions for individuals with specific medical conditions. Vaccination is especially crucial for individuals in high-risk groups, including pregnant women, young children, older adults, and individuals with chronic health conditions.

By getting vaccinated, you contribute to the overall health and well-being of your community.

Let’s get vaccinated!

Learn more about Matilda’s influenza vaccine prices

*The Scientific Committee on Vaccine Preventable Diseases (SCVPD)

Articles on this website are informative only and not intended to be a substitute for professional medical advice, diagnosis or treatment. They should not be relied upon for specific medical advice.

Information provided by:
Dr. CHUNG Sze Ting, Annie, Specialist in Family Medicine