What is influenza?
Influenza commonly referred to as flu which is an infectious disease caused by influenza viruses. Influenza is transmitted through droplet in the air by person to person during coughing or sneezing.
2022-2023 influenza vaccine (flu shot and nasal spray) is available. You may consider receiving the vaccine by nasal spray depending on your health condition and need. Please consult a doctor if you have any questions.
Under the Vaccination Subsidy Scheme (VSS) 2022/23, subsidised seasonal influenza vaccination will be provided to eligible Hong Kong residents starting from 6th Oct, 2022.
Flexibility could be exercised to provide seasonal influenza vaccine with COVID-19 vaccines on the same visit under informed consent.
If you have the following symptoms, call your doctor or get the person to a doctor right away and tell the doctor what happened, the date and time it happened, and when the vaccination was given.
- High fever
- Behavioral changes
- Difficulty in breathing
- Hoarseness of voice
- Fast heart beats
The viruses in inactivated influenza vaccine have been killed, severe problems from influenza vaccine are very rare.
- Redness, pain, swelling at injection site
- Fever, aches
(If these problems occur, they usually last 1 or 2 days)
Some people should not get inactivated influenza vaccine or should wait before getting it.
- Guillain-Barre Syndrome (a severe paralytic illness, also called GBS) - You may be able to get the vaccine, but your doctor should help you make the decision.
- If you are not feeling well - You should wait until recover before getting the flu vaccine. If you are ill, talk to your doctor or nurse about whether to reschedule the vaccination. People with a mild illness can usually get the vaccine.
- Any severe or life-threatening allergies (allergic reactions to influenza vaccine are rare)
- Influenza vaccine virus is grown in eggs. People with severe egg allergy should not get the vaccine.
- A severe allergy to any vaccine component is also a reason not to get the vaccine
- If you have had a severe reaction after a previous dose of influenza vaccine, tell your doctor
- 1 dose - Children age 9 years or above & Adult
- 2 dose - Children younger than 9 years of age getting influenza vaccine for the first time should have 2 doses (at least 4 weeks apart)
Persons aged 9 years or above are recommended to receive one dose of 2022-23 influenza vaccine. To ensure adequate immunity against seasonal influenza, children under 9 years old who have never received any seasonal influenza vaccine are recommended to be given 2 doses with a minimum interval of 4 weeks in the 2022-23 season. Children who have received at least one dose of seasonal influenza vaccine in the 2022-23 season or before are recommended to receive one dose in the 2022-23 season.
- Everyone from the age of 6 months
High risk groups are highly recommended to get vaccinated, they are:
- Pregnant women
- Patients with chronic illness (such as the heart, lung, kidney disease, metabolic disease and immune insufficiency)
- Healthcare providers
- Poultry workers
- Pig farmers
- Old age home residents
- Those living in residential care homes for the disabled
The best time to get influenza vaccine is from September every year.
In Hong Kong, seasonal influenza is usually more common in periods from January to March or April and from July to August. Getting the vaccine in December, or even later, will still be beneficial in most years.
It takes about 2 weeks for protection to develop after the vaccination, and protection can last up to a year.
Influenza viruses are always changing. Therefore, influenza vaccines are updated every year, and an annual vaccination is recommended.
Other illnesses have the same symptoms and are often mistaken for influenza. But only the influenza virus can cause influenza. For most people, the following symptoms can last only a few days, but some people get much sicker. Influenza can lead to pneumonia and can be dangerous for people with heart or breathing conditions. It can cause high fever and seizures in children.
- muscle ache
- sore throat