Medication · Vaccines

Influenza vaccine

Also known as: flu vaccine, flu jab, seasonal influenza vaccine, flu shot

The yearly flu vaccine: an inactivated or live attenuated vaccine reformulated each season to match circulating influenza strains, offered to people at higher risk of severe flu and to those who care for them.

Open in the 3D explorerLungs anatomyCheck interactions
3D model of the Lungs in the Anatomy Nexus anatomy atlas
Interactive 3D model: Lungs. Orbit, zoom and click the structures.Load the 3D model
Generic name
Influenza vaccine
Active ingredient
Influenza vaccine
Product type
Vaccine
Drug class
Influenza vaccines
Brand names
UK Fluenz (nasal spray), Fluad, Flucelvax, Supemtek · US Fluzone, Flublok, FluMist
Routes
Intramuscular, Intranasal (Intramuscular injection; intranasal spray (live attenuated vaccine))
Dosage forms
Prefilled syringe, Nasal spray
Also known as
flu vaccine, flu jab, seasonal influenza vaccine, flu shot
Forms
Single-dose prefilled syringe once each season (two doses for some young children in their first season); nasal spray for children
Onset and duration
Protection develops over about 10-14 days and lasts through the season.
Terminology
ATC J07BB
Monitoring
No tests; eligible groups are offered the vaccine every season and the strains are reviewed annually by WHO and national bodies.

Availability by country

CountryStatusNoteSource
UKPrescription onlyGiven free on the NHS to eligible groups each autumn; also available privately from pharmacies UK

Legal status differs between countries and can change; each row cites the document it was taken from and applies only to the country named.

What it is used for

  • Preventing seasonal influenza and its complications (pneumonia, hospital admission, worsening of heart and lung disease)
  • Protecting people around those at highest risk, including health and care workers

How it works in the body

The vaccine presents the immune system with the surface protein haemagglutinin from the influenza strains expected that season (or, in the nasal spray, weakened live viruses that grow only in the cooler nose). Over about two weeks the body makes antibodies and memory cells; if the real virus arrives, the antibodies block it from entering airway cells and the infection is prevented or made milder. Because the virus drifts each year and immunity wanes, the vaccine is reformulated and given annually.

Common side effects

  • A sore arm, mild fever, aches and tiredness for a day or two
  • A blocked or runny nose after the nasal spray

Serious: seek help

  • A severe allergic reaction, which is rare and treated on the spot
  • Guillain-Barré syndrome has been reported very rarely after influenza vaccination

Cautions and interactions

  • A previous severe allergic reaction to the vaccine or an ingredient
  • The live nasal spray is not given to people who are significantly immunosuppressed, are pregnant, or have severe asthma, and is delayed if wheezy
  • Vaccination is postponed during a feverish illness
  • The inactivated vaccine cannot cause flu; it does not protect against colds or other viruses

Interactions

Check interactions

Taking Influenza vaccine with other medicines? Add them to the checker to see what the official sources say about each pair: the mechanism, general management and monitoring, never a bare "safe".

Check Influenza vaccine interactions

Interactions documented in the official sources cited on each card. The list covers the medicines represented on this site and is not exhaustive; how the interaction data is compiled.

No pair records for this medicine are in the sources currently represented by Anatomy Nexus. Absence from this list does not mean no interaction exists.

Vaccine profile

Disease targets
Seasonal influenza
Platform
Inactivated (killed) whole organism
Antigen
Haemagglutinin of the influenza A and B strains recommended for the season (inactivated split-virion or subunit vaccines; a live attenuated nasal spray for children)
Combination vaccine
No
Age indication
From 6 months; the product used depends on age (a live attenuated nasal spray for most children, adjuvanted or high-dose inactivated vaccines for older adults)
Formulation
Prefilled syringe for injection; nasal spray (live attenuated)
Schedule. Offered every autumn to people at higher risk of complications (older adults, pregnant women, long-term conditions, care-home residents), to children in the eligible age groups, and to health and social care workers; the strains change each year so last season's vaccine does not cover this season. GLOBAL Schedules change; this note is versioned against the cited guidance and dated on this page.

Same-class and related medicines

Same class: Influenza vaccines

adjuvanted inactivated influenza vaccinehigh-dose inactivated influenza vaccineinactivated influenza vaccinelive attenuated influenza vaccine (nasal)recombinant influenza vaccine

Medicines that share the class of Influenza vaccine. They are separate medicines with their own licences, doses and interactions, not alternative names for Influenza vaccine.

Educational content. Anatomy Nexus provides medical education and does not replace professional medical advice, diagnosis, treatment, prescribing or pharmacist review. Doses, choices and monitoring are decided by a prescriber for an individual; never start, stop or change a medicine on the basis of this page.