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Influenza Vaccine

Influenza (flu) is a disease caused by a virus. Influenza can be caused by many types of influenza viruses. The most common types in Hong Kong are H1N1 and H3N2, which are influenza A and B viruses. The virus is mainly transmitted through respiratory droplets.

Epidemic seasonal influenza virus strains may change from time to time, and the composition of seasonal influenza vaccines must be updated annually according to the circulating strains to enhance protection.


Therefore, new influenza vaccines must be given every year. Immunity develops approximately two weeks after vaccination.


In 2019/20, the Scientific Committee on Vaccine Preventable Diseases recommends that the following people in Hong Kong receive priority vaccination:


  • Pregnant woman

  • Elders living in residential care homes;

  • Long-term boarders living in a home for the disabled;

  • Persons 50 years or older;

  • People with long-term health problems;

  • Medical staff

  • Children from 6 months to 11 years;

  • Poultry industry practitioners; and

  • Persons engaged in pig raising or slaughtering

Vaccine Type
Vaccine Type
HK Reg‭. ‬No‭.‬
Quadrivalent Vaccine





Quadrivalent Vaccine

Vaxigrip Tetra

Sanofi Pasteur 



Quadrivalent Vaccine



Influvac Tetra


Vaxigrip Tetra

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Influvac Tetra

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Q: Does the flu vaccine receive annual immunity to continue to gain immunity? Does it have any effect if we stop fighting for a year or two?

A: The flu virus types that flu vaccines prevent each year are not the same. Stopping the fight halfway is okay, but you will not be protected during this period, so it is best to fight every year.


Q: I got a flu shot in 2019. Can I get it now?

A: Yes. The first year of 2019 is the calculation of 2018-2019, and the end of 2019/2020 is the year of 2019-2020. There are differences in the types of influenza virus prevention.


Q: Can I take a shower and swim after the injection?

A: The flu needle is an intramuscular injection. The needle is fine and the shower can continue. But the needle is always a wound. If you are worried, you can avoid the needle and clean it with a damp cloth. For swimming, there is a chance of fever and tiredness after the injection, so swimming is not recommended.

Q: Is it sensitive to eggs?

A: It depends. If you are severely sensitive to eggs or even have difficulty breathing, you should not catch the flu. If the sensitivity is mild, we recommend consulting your doctor before making a decision.

Q: Can flu shots be used together with other shots?

A: Yes. Influenza can be treated with 13-valent pneumococcal vaccine or snake needles. However, be aware that doctors recommend that you get at most two vaccines in a day, or you can get other shots every two weeks.

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