4-Valent Influenza Vaccine 2025/26

What is influenza? Influenza, commonly known as the flu, is a disease caused by viruses and is highly contagious. In Hong Kong, the peak seasons for the flu are usually from January to March and from July to August. The flu is caused by various types of viruses, categorized into three main types: Type A, Type B, and Type C, with Type A being the most prevalent. In Hong Kong, the two most common strains of Type A flu viruses are H1N1 and H3N2. The flu virus constantly mutates, giving rise to new variants and facilitating rapid transmission within communities. As a result, the viral components of the flu vaccine change each year.
How does the flu virus spread? What are the symptoms? The flu is an acute respiratory disease primarily transmitted through the air or respiratory droplets in crowded, enclosed environments. It can also spread through direct contact with the secretions of infected individuals. Symptoms include: - Fever - Headache - Muscle pain - Runny nose - Cough - Sore throat - Fatigue Milder cases generally recover within two to seven days on their own. However, elderly individuals and those with weakened immune systems who contract the flu are at risk of severe symptoms, and complications such as bronchitis or pneumonia may arise, with the most severe cases leading to death.
Why receive a flu vaccine annually? When is the best time to get vaccinated? Receiving the flu vaccine is one of the effective methods to prevent the flu and reduce its complications. To prepare for the upcoming flu peak season and the latest strains of flu viruses, individuals should get vaccinated at least two weeks before the peak season arrives. This allows sufficient time for the body to develop antibodies. Especially for high-risk groups (such as those with chronic illnesses, individuals aged 65 or above, children aged six months or above, and healthcare workers), considering vaccination is highly recommended.