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Frequently Asked Questions on Seasonal Influenza Vaccine (Southern Hemisphere) and Vaccination

Frequently Asked Questions on Seasonal Influenza Vaccine (Southern Hemisphere) and Vaccination
2015-05-07
  1. Why should Seasonal Influenza Vaccine (SIV) be needed in Hong Kong? What is the benefit?
  2. Who should receive the southern hemisphere SIV? What are the target / high risk / priority groups? Should I receive SIV (southern hemisphere) if I have already been vaccinated with SIV 2014/15 (northern hemisphere)?
  3. Is seasonal influenza vaccine safe and effective? Any side-effect?
  4. What is the recommended interval between injection of two SIVs (southern hemisphere SIV and northern hemisphere SIV)?
  5. What is the component of the SIV (southern hemisphere)?
  6. Does the SIV (southern hemisphere) work right away? How long does it take to develop antibodies?
  7. Can the SIV (southern hemisphere) be received with other vaccine?
  8. Does the SIV (southern hemisphere) contain human swine influenza virus?
  9. Does the SIV (southern hemisphere) contain the circulating influenza virus (H3N2 Inf (A) virus)? Do I have enough protection against influenza virus if I receive both SIVs from northern and southern hemisphere?
  10. Who should not receive SIV (southern hemisphere)? What are the contra-indications?
  11. Is SIV (southern hemisphere) a live attenuated or inactivated vaccine? 
  12. What is the difference between the components of SIV 2014/15 (northern hemisphere) and SIV 2015 (southern hemisphere)?
  13. Can the recipient be vaccinated with SIV (southern hemisphere) if he is not feeling well on the day of vaccination?
  14. Some of the residents/elders have already been infected with influenza A (H3N2). Should they be vaccinated with SIV (southern hemisphere)?
  15. Can one receive southern hemisphere SIV when taking or having taken Tamiflu?
  16. Can the SIV (southern hemisphere) be received with pneumococcal vaccine at the same time?
  17. Would it be safe to receive both SIVs of northern and southern hemisphere at the same time if the resident/elder has not received the SIV (northern hemisphere) yet? If not, which SIV (northern or southern) to take?

1. Why should Seasonal Influenza Vaccine (SIV) be needed in Hong Kong? What is the benefit?

Seasonal influenza vaccination is one of the effective means to prevent seasonal influenza and its complications together with reduction in influenza related hospitalisation and death.

Vaccination is especially important for people at higher risk of serious influenza complications, and for people who live with or care for high risk individuals.

2. Who should receive the southern hemisphere SIV? What are the target / high risk / priority groups? Should I receive SIV (southern hemisphere) if I have already been vaccinated with SIV 2014/15 (northern hemisphere)?

The SIV (southern hemisphere), when available, will be given by phases to the elderly, starting from the oldest age group, such as those aged 85 or above, in the community first as they are at higher risk of developing severe illness after infecting influenza. The SIV (southern hemisphere) will also be given to residents of Residential Care Homes for the Elderly.

The SIV (southern hemisphere) will be offered to these target / priority groups regardless of whether they have received the SIV 2014/15 (northern hemisphere).

3. Is seasonal influenza vaccine safe and effective? Any side-effect?

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 to 2 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 Scientific Committee on Vaccine Preventable Diseases (SCVPD) had conducted two meetings to discuss the use of SIV (southern hemisphere) in February and March 2015. The Committee concluded that the SIV (southern hemisphere) is safe.

Seasonal influenza vaccine is about 70 to 90% effective in preventing illness from seasonal influenza in healthy adults when the vaccine and circulating viruses are well-matched. For prevention against influenza, vaccinated individuals should also maintain good personal and environmental hygiene practices, balanced diet, regular exercise, adequate rest, and no smoking.

4. What is the recommended interval between injection of two SIVs (southern hemisphere SIV and northern hemisphere SIV)?

The Scientific Committee on Vaccine Preventable Diseases (SCVPD) recommended two doses of inactivated seasonal influenza vaccines to be separated by at least 4 weeks.

5. What is the component of the SIV (southern hemisphere)?

The trivalent SIV (southern hemisphere) we use contain the following viruses:

  • an A/California/7/2009 (H1N1)pdm09-like virus
  • an A/Switzerland/9715293/2013 (H3N2)-like virus
  • a B/Phuket/3073/2013-like virus

6. Does the SIV (southern hemisphere) work right away? How long does it take to develop antibodies?

No. It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection. For prevention against influenza, vaccinated individuals should still maintain good personal and environmental hygiene practices, balanced diet, regular exercise, adequate rest, and no smoking.

7. Can the SIV (southern hemisphere) be received with other vaccine?

Yes, it can be administered at the same time as other vaccines, but the vaccines should be administered with different syringes at different injection sites.

8. Does the SIV (southern hemisphere) contain human swine influenza virus?

Yes. The trivalent SIV (southern hemisphere) we use contain the following viruses:

  • an A/California/7/2009 (H1N1)pdm09-like virus (human swine influenza virus)
  • an A/Switzerland/9715293/2013 (H3N2)-like virus
  • a B/Phuket/3073/2013-like virus

9. Does the SIV (southern hemisphere) contain the circulating influenza virus (H3N2 Inf (A) virus)? Do I have enough protection against influenza virus if I receive both SIVs from northern and southern hemisphere?

The trivalent SIV (southern hemisphere) we use contains the following viruses:

  • an A/California/7/2009 (H1N1)pdm09-like virus
  • an A/Switzerland/9715293/2013 (H3N2)-like virus
  • a B/Phuket/3073/2013-like virus

Seasonal influenza vaccine is about 70 to 90% effective in preventing illness from seasonal influenza in healthy adults when the vaccine and circulating viruses are well-matched. For prevention against influenza, vaccinated individuals should also maintain good personal and environmental hygiene practices, balanced diet, regular exercise, adequate rest, and no smoking.

10. Who should not receive SIV (southern hemisphere)? What are the contra-indications?

Those with severe hypersensitivity to egg proteins or any components of the vaccine or life-threatening reactions after previous administration of any influenza vaccine should not receive seasonal influenza vaccine. Those with bleeding disorders or on warfarin, or with a history of Guillain-Barré Syndrome should consult doctor before vaccinations.

11. Is SIV (southern hemisphere) a live attenuated or inactivated vaccine?

The trivalent SIV (southern hemisphere) we use is inactivated seasonal influenza vaccine.

12. What is the difference between the components of SIV 2014/15 (northern hemisphere) and SIV 2015 (southern hemisphere)?

The trivalent SIV 2015 (southern hemisphere) we use 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

The trivalent SIV 2014/15 (northern hemisphere) contains the following:

  • an A/California/7/2009 (H1N1)pdm09-like virus
  • an A/Texas/50/2012 (H3N2)-like virus
  • a B/Massachusetts/2/2012-like virus

Quadrivalent SIV 2014/15 (northern hemisphere) contains the above three viruses and a B/Brisbane/60/2008-like virus.

13. Can the recipient be vaccinated with SIV (southern hemisphere) if he is not feeling well on the day of vaccination?

Minor illnesses such as upper respiratory tract infections are not contraindications to vaccination. Vaccination may also be deferred until symptoms subside in case of any worry.

14. Some of the residents/elders have already been infected with influenza A (H3N2). Should they be vaccinated with SIV (southern hemisphere)?

Residents/elders who have already had influenza should still receive SIV because SIV contain several different viruses so it may protect against influenza caused by different viruses.

15. Can one receive southern hemisphere SIV when taking or having taken Tamiflu?

Taking or having taken Tamiflu is not a contraindication to be vaccinated with SIV (southern hemisphere).

16. Can the SIV (southern hemisphere) be received with pneumococcal vaccine at the same time?

Yes, it can be administered at the same time as other vaccines, but the vaccines should be administered with different syringes at different injection sites.

17. Would it be safe to receive both SIVs of northern and southern hemisphere at the same time if the resident/elder has not received the SIV (northern hemisphere) yet? If not, which SIV (northern or southern) to take?

Residents/elders who have not received the SIV 2014/15 (northern hemisphere) should receive SIV 2015 (southern hemisphere) now.