Protect yourself from Influenza
Influenza vaccination helps (2008-2009)

What is influenza?
Influenza is an infectious disease caused by various types of influenza virus. The virus mainly spreads by respiratory droplets. The disease is characterised by fever, sore throat, cough, headache, muscle pains, runny nose and general tiredness. It is usually self-limiting with recovery in two to seven days. However, it can be a serious illness to the weak and frail, or elderly persons, and may be complicated by bronchitis, pneumonia or even death in the most serious cases.

Why is influenza vaccination important?
Influenza vaccination is one of the effective means to prevent influenza and its complications.

Who should receive influenza vaccination?
In 2008-2009, the Scientific Committee on Vaccine Preventable Diseases recommends the following target groups for influenza vaccination in Hong Kong:
- Elderly persons living in residential care homes                        
- Long-stay residents of institutions for the disabled
- Elderly persons aged 65 years or above                                   
- Persons with chronic illnesses*
- Children between the age of 6 months and less than 6 years      
- All pregnant women
- Health care workers
- Poultry workers

Members of the other groups who wish to obtain influenza vaccine for their personal protection can consult their general practitioners.
* People with chronic illnesses mainly refer to those who have chronic cardiovascular (except hypertension without complication), lung, metabolic or kidney disease, who are immunocompromised, children and adolescents (aged 6 months to 18 years) on long-term aspirin therapy, and those with chronic neurological condition that can compromise respiratory function or the handling of respiratory secretions or that can increase the risk for aspiration or those who lack the ability to care for themselves.

Who should not receive influenza vaccination?
People who are allergic to eggs, a previous dose of influenza vaccine or other vaccine components (e.g. neomycin, polymyxin) are not suitable to have the influenza vaccination. If an individual suffers from fever on the day of vaccination, the vaccination should be deferred till recovery.

Can pregnant women receive influenza vaccination?
The World Health Organization considers inactivated influenza vaccine safe in pregnancy and there is no evidence showing such vaccine can cause abnormality in foetus even if given during the first trimester. Pregnant women should consult obstetric doctors for any queries.

What are the possible side effects of the vaccine?
Influenza vaccine is very safe and usually well tolerated apart from occasional soreness, redness or swelling at the injection site. Some recipients may experience fever, muscle and joint pains, and tiredness beginning 6 to 12 hours after vaccination and lasting up to two days. If fever or discomforts persist, please consult a doctor. Immediate severe allergic reactions like hives, swelling of the lips or tongue, and difficulties in breathing are rare and require emergency consultation.
The influenza vaccine may rarely cause serious adverse events such as Guillain-Barre syndrome (1 to 2 case per million vaccinees), meningitis or encephalopathy (1 in 3 million doses distributed) and severe allergic reaction (anaphylaxis) (9 in 10 million doses distributed).

Does the vaccine work right away?
No. It takes about two weeks for antibodies to develop in the body and provide protection against influenza virus.

How much protection does the vaccine provide?
The vaccine currently in use helps to reduce the chance of influenza and its complications, but it does not offer 100% protection. Vaccinated persons may still develop influenza, especially when the circulating influenza viruses differ significantly from the vaccine strains. For prevention against influenza, vaccinated individuals should still maintain good personal and environmental hygiene practices, balanced diet, regular exercise, adequate rest, and no smoking.

Should I need to get vaccinated for influenza every year?
Yes. The circulating influenza strains may change from time to time. In accordance to the circulating strains, there will be an update of the vaccine composition each year to enhance protection. Moreover, the immunity built up in a vaccinated person will decrease over time and may become too low to provide protection after one year.

How to get further information?
For more health information, please:
- Visit the website of the Centre for Health Protection www.chp.gov.hk
- Call the 24-Hour Health Education Hotline of the Department of Health 2833 0111
The public can consult a doctor for influenza vaccination.