Q: When is the influenza season in Hong Kong?
In Hong Kong, influenza is most prevalent in January-March/April and July-August.
Q: How is influenza spread?
The flu is transmitted, or spread, when a person who has the flu coughs, sneezes, or spits, thus sending the droplets with flu virus into the air, where other people may inhale the virus. The virus then enters the nose, throat, or lungs of a person and begins to multiply, causing symptoms of influenza.
Q: Who are the people at high risk for developing complications from influenza?
The following groups are at increased risk for serious complications from or transmission of the flu:
- Persons aged >50 years
- Children aged 6 months to 5 years
- Residents of nursing homes and other long-term care facilities that house persons of any age who have long-term illnesses
- Adults or children > 6 months of age who have chronic heart or lung conditions, including asthma
- Adults or children > 6 months of age who need regular medical care or had to be in a hospital because of metabolic diseases (like diabetes), chronic kidney disease, obese individuals with body mass index > 30, or weakened immune system (including immune system problems caused by medicine or human immunodeficiency virus)
- Children and teenagers (aged 6 months to 18 years) who are on long-term aspirin therapy and therefore could develop Reye’s Syndrome after the flu
- Pregnant women at all stages
- Healthcare workers and other workers in a healthcare facility including clinics, hospitals and elderly homes
- Poultry workers, pig farmers and pig-slaughtering industry personnel
Q: Why do I need to get vaccinated every year?
The circulating seasonal influenza strains change from year to year; hence the influenza vaccine is updated each year to include the circulating strains to enhance protection. The natural protection or immunity you develop after catching a particular strain of influenza virus does not necessarily protect you against another strain of influenza virus. Besides, after you get a flu shot, your immunity to the flu declines over time and may not provide adequate protection after one year.
Q: Can severe problems occur after receiving the influenza vaccine?
Life-threatening allergic reactions are rare. These reactions tend to occur among persons with a severe allergy to eggs, because the viruses used in the inactivated influenza vaccines (IIV) and Live-attenuated influenza Vaccine (LAIV) are grown in chicken eggs. People who have had a severe reaction to eggs or to flu shot in the past, should not be vaccinated with IIV or LAIV before consulting a doctor.
Guillain–Barré syndrome (GBS) is a condition characterized by fever, nerve damage and muscle weakness. GBS can develop following a variety of infections, including influenza. So far, there is no conclusive evidence supporting a causal relationship between seasonal influenza vaccine and GBS.
Q: Can I take influenza vaccine together with other vaccines?
For Inactivated influenza vaccine (IIV) or recombinant influenza vaccine (RIV), they can be given at the same time or at any time before or after other inactivated vaccine (e.g. Pneumococcal Vaccine) or live vaccine (e.g. Measles, mumps and rubella vaccine). Different vaccines should be given with a different syringe and at a different injection site if IIV and other vaccines are given at the same time.
For live attenuated influenza vaccine (LAIV), any other live vaccines should be administered at least four weeks apart.
