Why is seasonal influenza vaccination important?

Seasonal influenza vaccination (SIV) is one of the effective means in preventing influenza and its complications together with reduction in influenza-associated hospitalisation and death.

Given that SIV offers protection against clinical influenza and severe cases do occur in previously healthy persons, all members of the public aged 6 months or above, except those with known contraindications, should receive SIV annually for personal protection.

When should I get vaccinated?

The Scientific Committee on Vaccine Prevention Diseases (SCVPD) recommended that October-November is the most optimal time for vaccination. Since it takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection, it is advised to get vaccinated at least two weeks before the onset of the main influenza season. However, even if seasonal influenza vaccination is not received before the recommended period, it can still be received as soon as possible.

What are the possible side effects following inactivated influenza vaccine administration?

The most common side effects following inactivated influenza vaccine administration are local reactions, which include pain, redness or swelling at the injection site. Some recipients may experience fever, chills, muscle pain and tiredness.

Side effects are generally mild and temporary. If you experience persistent fever, severe allergic reactions (e.g. difficulty in breathing, swelling of the lip or tongue, hives, etc.) or other adverse events after receiving vaccination, please consult a doctor immediately.

Who should not receive inactivated influenza vaccine?

People who have a history of severe allergic reaction to any vaccine component or a previous dose of any influenza 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 seasonal influenza vaccination in primary care setting, provided they undergo a 30-minute observation period following vaccination. Individuals with a history of anaphylaxis to egg should have seasonal influenza vaccine administered by healthcare professionals in appropriate medical facilities with capacity to recognise and manage severe allergic reactions. Influenza vaccine contains ovalbumin (an egg protein), but the vaccine manufacturing process involves repeated purification and the ovalbumin content is very low. Even people who are allergic to eggs are generally safe to receive vaccination.

Those with bleeding disorders or on anticoagulants should consult their doctors for advice. If an individual suffers from fever on the day of vaccination, vaccination should be deferred till recovery. Please consult your doctor for details.

Is it necessary to get vaccinated against seasonal influenza every year?

Seasonal influenza vaccination requires annual administration. Evidence on repeated influenza vaccination shows that vaccination in the current and prior season provides better protection than no vaccination or being vaccinated in the prior season only. Furthermore, the circulating seasonal influenza strains may change from time to time and the vaccine composition is updated every year in accordance with the circulating strains to enhance protection.

Can pneumococcal vaccine be given together with seasonal influenza vaccine?

Yes. Pneumococcal vaccine can be given with seasonal influenza vaccine at the same clinic visit, but should be administered with a different syringe and at a different injection site if inactivated influenza vaccine is used.

Can COVID-19 vaccine be given together with seasonal influenza vaccine?

COVID-19 vaccines can be co-administered with seasonal influenza vaccine on the same visit under informed consent for administrative convenience and achieving better coverage.

For details on seasonal influenza vaccination programme, please refer to Centre for Health Protection's Vaccination Schemes page.