2016-01-29
- What is the recommended 2015/16 seasonal influenza vaccine composition?
- How many shots of influenza vaccination will persons with intellectual disability need?
- Can a child given a full adult dose be waived a second dose?
- When is the optimal time for persons with intellectual disability to receive influenza vaccination?
- What kinds of seasonal influenza vaccines are covered in PIDVSS?
- Who should not receive inactivated seasonal influenza vaccination?
- Is seasonal influenza vaccine safe? What are the possible side effects of the inactivated seasonal influenza vaccine?
- How to choose the trivalent or quadrivalent vaccine? How much is the difference in protection between them?
1. What is the recommended 2015/16 seasonal influenza vaccine composition?
The vaccine recommended by the Scientific Committee on Vaccine Preventable Diseases (SCVPD) in 2015/16 contains the following:
- an A/California/7/2009 (H1N1) pdm09-like virus
- an A/Switzerland/9715293/2013 (H3N2)-like virus
- a B/ Phuket/3073/2013-like virus
If quadrivalent influenza vaccine is being used, it shall contain the above three viruses and a B/Brisbane/60/2008-like virus.
2. How many shots of influenza vaccination will persons with intellectual disability need?
Persons aged 9 years or above are recommended to receive one dose of 2015/16 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 of seasonal influenza vaccine with a minimum interval of 4 weeks. Children who have received seasonal influenza vaccine in the 2014/15 season or before are recommended to receive one dose in the 2015/16 season.
3. Can a child given a full adult dose be waived a second dose?
No. A full adult dose of influenza vaccine cannot substitute a second dose. To ensure adequate immunity against influenza, children under 9 years old who have never received any influenza vaccine are recommended to have 2 doses of influenza vaccine with a minimum interval of 4 weeks.
4. When is the optimal time for persons with intellectual disability to receive influenza vaccination?
As it usually takes about two weeks after vaccination for antibodies to develop in the body and provide protection against seasonal influenza virus, parents / guardians are advised to bring their children / wards to participating private medical doctors’ clinics for vaccination as early as possible.
5. What kinds of seasonal influenza vaccines are covered in PIDVSS?
The PIDVSS will cover the types of seasonal influenza vaccines recommended by the SCVPD that are registered for use and supplied in Hong Kong.
6. Who should not receive inactivated seasonal influenza vaccination?
People who are allergic to a previous dose of inactivated influenza vaccine or other vaccine components (please refer to the insert of the vaccine) are not suitable to have inactivated seasonal influenza vaccination. Individuals with mild egg allergy who are considering an influenza vaccination can be given inactivated influenza vaccine in primary care. Individuals with diagnosed or suspected severe egg allergy should be seen by an allergist/immunologist for evaluation of egg allergy and for administration of inactivated influenza vaccine if clinically indicated. Those with bleeding disorders or on anticoagulants may receive the vaccine by deep subcutaneous injection*. If an individual suffers from fever on the day of vaccination, the vaccination should be deferred till recovery.
(* Note: All doctors are advised to read carefully the product information of the vaccine they have procured, noting especially the contra-indications, route of administration, dosage for children and expiry date.)
7. Is seasonal influenza vaccine safe? What are the possible side effects of the inactivated seasonal influenza vaccine?
Inactivated seasonal 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.
Influenza vaccination may be rarely followed by serious adverse events such as Guillain-Barré syndrome (1.03 cases per million vaccinees), meningitis or encephalopathy (1 in 3 million doses distributed) and severe allergic reaction (anaphylaxis) (9 in 10 million doses distributed). However, influenza vaccination may not necessarily have causal relations with these adverse events. The risk of Guillian-Barré Syndrome after influenza infection (17.20 per million) is higher than after influenza vaccination (1.03 per million).