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Seasonal Flu Vaccine

The flu, also known as influenza, is an acute illness affecting the respiratory system which originates from influenza viruses. In Hong Kong, H1N1 and H3N2 subtypes of influenza A virus along with influenza B virus are observed most frequently in January to March/April and July to August. Symptoms such as fever, sore throat, coughing, runny nose, headache, muscle pain and weariness usually appear due to this condition.

The virus is highly contagious and primarily transmitted through respiratory droplets and close contact. To prevent infection, it’s important to practice good personal hygiene habits such as frequent hand washing and receiving the flu vaccine.

What are the symptoms of Influenza?

Flu manifests through the typical symptoms of a sore throat, cough, runny nose, fever, fatigue and gastrointestinal distress such as vomiting or diarrhea. Most healthy individuals will recuperate within 1 week but those with severe symptoms or weakened immunity may experience them for longer periods.

How to prevent Influenza?

The occurrence of the seasonal flu could be averted through:

Get flu vaccination

Getting a flu shot is an effective measure to avoid contracting the flu. As seasonal influenza strains have the potential to mutate, annual updates are made to the components of the vaccine. Therefore, it’s advisable to receive an annual flu shot for optimal protection against contracting this illness.

Maintain personal and environmental hygiene

Regularly washing one’s hands is an effective measure for controlling the transmission of the virus, especially after being in communal spaces or coming into contact with a person infected by it. Furthermore, consistently sanitizing commonly used items such as mobile devices, furniture, and toys can effectively impede the spread of infectious diseases.

Maintain healthy lifestyle

Maintaining a healthy lifestyle can aid in enhancing the immune system, which includes consuming sufficient servings of fresh vegetables and fruits, engaging in regular physical activity, getting proper rest and more.

Quit or reduce drinking and smoking

Consumption of alcohol and tobacco can compromise the immune system, thereby increasing vulnerability to flu infection. As a result, individuals should either abstain from or limit their alcohol and tobacco intake for better health outcomes.

Get the Vaccine, Prevent Influenza

Receiving the flu vaccine is an efficacious method of protecting against influenza infection. Listed below are reasons why obtaining the flu vaccine is significant:

Prevent influenza infection

The influenza vaccine is a highly effective method for preventing seasonal flu and its associated complications. It can also significantly decrease the occurrence of hospitalizations and fatalities related to influenza infections.

Avoid severe symptoms

Receiving a flu vaccine can help prevent the development of severe symptoms and decrease the likelihood of complications, including but not limited to pneumonia, heart disease, encephalitis.

Protect high-risk groups

Individuals at a higher risk of severe influenza and its related complications are the elderly, pregnant women, infants, and those with suppressed immunity. To safeguard these vulnerable groups from flu transmission, healthy individuals can opt for influenza vaccination as it offers significant protection against the virus.

Virus transmission control

Receiving the flu shot has the potential to decrease the transmission of influenza, which could effectively manage its prevalence within the community.

Who needs to get Influenza vaccination?

The influenza vaccine is both safe and efficient, making it a recommended practice for all individuals six months of age or older. 

Furthermore, certain groups of people are at a higher risk of spreading the virus or experiencing severe symptoms themselves. These priority groups are strongly recommended to get vaccinated against influenza:

  • Healthcare workers (including care workers in Residential Care Homes for the Elderly [RCHE] and Residential Care Homes for Persons with Disabilities [RCHD])
  • Persons aged 50 years or above
  • Pregnant women
  • Residents of Residential Care Homes (such as RCHE or RCHD)
  • Persons with chronic medical problems, such as people with chronic cardiovascular, metabolic or kidney diseases, obesity, weakened immunity, etc.
  • Children aged 6 months to 11 years
  • Poultry workers
  • Pig farmers and pig-slaughtering industry personnel
  • Secondary school student

Injected Flu Vaccine & Nasal Spray Flu Shot

There exist two types of influenza vaccinations, namely the inactivated influenza vaccine (IIV), which is administered through injection, and the live attenuated influenza vaccine (LAIV), which is delivered via intranasal spray. The following are some particulars regarding each type.

Inactivated influenza vaccine (IIV) through injection

The IIV is formulated with the viruses that have been inactivated (killed) during the manufacturing process, triggering the immune responses and increasing immunity towards Influenza.

Live attenuated influenza vaccine (LAIV) through intranasal spray

LAIV contains viruses that are still alive but already attenuated (i.e. weakened/tamed). The attenuated viruses are validated by the medical science that they only trigger restricted growth in the body, and can hardly replicate themselves to manifest into the real illness.

Humansa provides Influenza vaccination

Composition of Influenza Vaccine

World Health Organization (WHO) recommends that quadrivalent vaccines for use in the 2023-2024 influenza season contain the following:
(Egg-based quadrivalent vaccines)

  • A/Victoria/4897/2022 (H1N1) pdm09-like virus
  • A/Darwin/9/2021 (H3N2)-like virus
  • B/Austria/1359417/2021 (B/Victoria lineage)-like virus
  • B/Phuket/3073/2013 (B/Yamagata lineage)-like virus

Flu Vaccine (Injection Shot)

Suitable for people aged 6 or above

Flu Vaccine (Nasal Spray)

Suitable for people aged 2 – 49

FAQs of Influenza vaccine

How likely is it to experience adverse reactions after getting the flu shot?

Receiving a flu shot is typically considered safe, although there may be some adverse reactions like tenderness and inflammation at the injection site, fever, headache or other related symptoms. It is important to note that most individuals do not experience these symptoms and they are typically temporary as well as mild in nature.

Does the immunity provided by the flu shot last forever? At what frequency should I receive influenza vaccination?

Over time, the protection acquired from vaccination diminishes and may eventually provide no safeguard against seasonal influenza. Since seasonal influenza strains may vary over time, the formulation of the vaccination is updated annually; as a result, it is highly advised to receive flu shots every year.

The above information is for reference only and shall not be considered as medical advice. Please consult with your doctor or healthcare provider for further enquiries.