Influenza Vaccination

oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

Influenza is a major cause of morbidity and mortality each year in the UK. Vaccination has been available since the late 1960s. It is offered annually to patients aged 65, and all those aged 6 months and over in clinical risk groups identified by the Department of Health (DH).[1] In addition, from September 2013 all 2-year-old children will be offered nasal influenza immunisation, with roll-out to pre-school and primary school children in 2014. Secondary schools will be piloted in 2014, with roll-out in 2015.

A Cochrane review found that the available evidence regarding the safety, efficacy or effectiveness of influenza vaccines for people aged 65 years or older is of poor quality and provides no guidance.[2] 

The World Health Organization (WHO) monitors influenza viruses throughout the world and recommends which strains are to be included in the current year's vaccine.

The UK generally uses trivalent vaccines (against two strains of influenza A and one of B), which give about 70-80% protection as long as the virus matches the strains against which the vaccine was prepared. From September 2013, a live, attenuated vaccine (Fluenz®) will be offered to all children aged 2 years. All take 10-14 days to produce active antibody levels.[1] 

  • Protection may be less in the elderly, but immunisation has been shown to reduce the incidence of bronchopneumonia, mortality and hospital admission.
  • In children, Fluenz® has been shown to provide greater protection than the inactivated vaccine.[1] 
  • The vaccine needs to be given annually to provide protection from the antigenically changed nature of the prevailing virus. In the event of a major antigenic shift liable to cause an epidemic or pandemic, it is likely that a monovalent vaccine would be prepared.
  • Immunisation should be carried out between September and early November. Although most cases occur from mid-November, it is not unknown for the influenza season to start earlier.
  • Vaccines are normally given intramuscularly (IM) into the upper arm or anterolateral thigh.
  • Intanza® is also available as an intradermal preparation. Fluenz® is a nasal spray used for children aged 2-18 years.[3] 
  • If patients have a bleeding disorder (eg, haemophilia), deep subcutaneous injection is appropriate.
  • Children require a second dose of vaccine four weeks after the first, if they are receiving the vaccine for the first time, to achieve optimum antibody levels.
  • Influenza vaccine can be given with other vaccines, preferably in different limbs. If both vaccines have to be given in the same limb, the sites should be at least 2.5 cm apart.[1] 
  • The batch numbers and sites of the vaccines should be recorded in the patient's notes.
  • If the vaccine is given for employment purposes, the employer should also keep a record.[1]

The percentage uptake for patients aged 65 years and over in England in 2010/2011 was 73%. Vaccine uptake in risk groups aged under 65 years was approximately 50% in England.[4] Uptake has been noted to be low in healthcare workers.[5][6]

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  • Store at 2-8°C and protect from light.
  • Discard if frozen.
  • Extremes of temperature can reduce potency. Freezing can cause hairline cracks in the container.
  • All vaccines are supplied in the inactive form in pre-filled syringes (or a nasal applicator) which should be shaken before use.[1] Dispose of the vaccination equipment in a sealable, puncture-proof sharps box (UN-approved BN7390).

All currently available vaccines are grown in embryonic hens' eggs and then chemically inactivated and purified. There are three types available:[1]

  • 'Split virion, inactivated' or 'disrupted virus' vaccines - the whole virus is inactivated by exposing to organic solvents or detergents.
  • 'Surface antigen, inactivated' vaccines - these contain haemagglutinin and neuraminidase antigens prepared from disrupted viruses.
  • A live, attenuated vaccine - Fluenz®, which is preferred for children aged 2-18 years because it provides a higher level of protection.

There is no difference between the first two types of vaccines in efficacy or adverse reactions.[1] Being inactivated, they do not cause the diseases against which they protect. Fluenz® should not be given to pregnant women. The live attenuated vaccine has been shown to have increased efficacy in children aged 2-18 years.[1] 

Children not in a clinical risk group only require one dose of the vaccine. Children in clinical risk groups aged 2 years or older but under 9 years who have not received influenza vaccine before should receive a second dose of vaccine at least four weeks later.

Immunocompetent patients

  • Immunocompetent adults, including pregnant women, and children aged 13 years and over should be given a single dose of trivalent vaccine.
  • Children NOT in clinical risk groups only require one dose of vaccine.
  • Children in clinical risk groups aged 2 to under 9 years who have not received influenza vaccine before should receive a second dose of vaccine at least four weeks later.
  • Vaccinated children should avoid contact with severely immunocompromised individuals for two weeks after vaccination.

Immunocompromised patients

Immunocompromised patients (including HIV infection, regardless of CD4 count) should be given influenza vaccine in accordance with the recommendations above. The may not make a full antibody response, so protection may not be as high as for immunocompetent patients. Consideration should also be given to vaccinating household contacts of immunocompromised patients, ie those sharing living accommodation on most days over the winter.

Immunocompromised children, and those living in close contact with those who are immunocompromised, should be offered trivalent vaccine.

Target group of at-risk for influenza

The national policy is that influenza vaccine should be offered to the following groups:

  • All those aged 65 years and over.
  • Residents of nursing or residential homes for the elderly and other long-stay facilities.
  • Carers of persons whose welfare may be at risk if the carer falls ill.
  • All those aged 6 months or over in a clinical risk group (listed below).

In 2012, the Joint Committee on Vaccination and Immunisation recommended that the influeza vaccination programme should be extended to all children aged 2 to 16 years:[1] 

  • The phased introduction of this extension began in September 2013 with the inclusion of children aged 2 and 3 years in the routine programme.
  • This initially includes nasal flu vaccine being offered to all children aged 2 years or 3 years, but not 4 years or older on or before 1 September 2013 (date of birth on or after 2 September 2009 and on or before 1 September 2011).
  • The programme will be fully rolled out to all pre-school and primary school-aged children from 2014. Secondary school children may be part of pilot schemes from 2014, with full roll-out planned from 2015.
Clinical risk groups Examples (decision based on clinical judgement)
Chronic respiratory disease
  • Chronic obstructive pulmonary disease (COPD), including chronic bronchitis and emphysema; bronchiectasis, cystic fibrosis, interstitial lung fibrosis, pneumoconiosis and bronchopulmonary dysplasia (BPD).
  • Asthma - with disease which requires continuous or repeated use of inhaled or systemic steroids or with previous exacerbations requiring hospital admission.
  • Children who have previously been admitted to hospital for lower respiratory tract disease.
Chronic heart disease
  • Congenital heart disease.
  • Hypertension with cardiac complications.
  • Chronic heart failure.
  • Individuals requiring regular medication and/or follow-up for ischaemic heart disease.
Chronic kidney disease
  • Chronic renal failure.
  • Nephrotic syndrome.
  • Renal transplantation.
Chronic liver disease
  • Cirrhosis.
  • Biliary atresia.
  • Chronic hepatitis.
Chronic neurological disease
  • Stroke.
  • Transient ischaemic attack (TIA).
  • Type 1 diabetes.
  • Type 2 diabetes requiring insulin or oral hypoglycaemic drugs.
  • Diet-controlled diabetes.
  • Immunosupression due to disease or treatment.
  • Patients undergoing chemotherapy leading to immunosuppression.
  • Asplenia or splenic dysfunction.
  • HIV infection.
  • Individuals treated with, or likely to be treated with, systemic steroids for more than a month at a dose equivalent to prednisolone at 20 mg or more per day (any age) or, for children under 20 kg, a dose of 1 mg or more per kg per day.
    Some immunocompromised patients may have a suboptimal immunological response to the vaccine.

All pregnant women should receive the trivalent seasonal influenza vaccine.

The target groups for a one-off pneumococcal vaccination are very similar (see the separate article on Pneumococcal Vaccine) so often both are given together in 'flu clinics'.

  • Those living in long-stay residential care homes or other long-stay care facilities, where rapid spread is likely to follow introduction of infection and cause high morbidity and mortality (this does not include prisons, young offender institutions, university halls of residence, etc).
  • Those who are in receipt of a carer's allowance, or those who are the main carer for an elderly or disabled person whose welfare may be at risk if the carer falls ill. This should be given on an individual basis, at the GP's discretion, in the context of other clinical risk groups in their practice.

GPs should take into account the risk of influenza infection exacerbating any underlying disease that a patient may have, as well as the risk of serious illness from influenza itself. GPs should consider on an individual basis the clinical needs of their patients, including individuals with:

  • Multiple sclerosis and related conditions.
  • Hereditary and degenerative diseases of the central nervous system.

NB: individuals working closely with poultry are no longer thought to be high-risk.

Employers - eg, healthcare trusts, nursing and care homes - should offer influenza vaccination to staff directly involved in patient care as an adjunct to good infection control procedures:

  • Clinicians, midwives and nurses, paramedics and ambulance drivers.
  • Occupational therapists, physiotherapists and radiographers.
  • Primary care providers such as GPs, practice nurses and district nurses.
  • Staff who look after older people in nursing and care homes.

There are few contra-indications.[1] When in doubt, seek the guidance of a local communicable disease consultant, paediatrician or immunisation co-ordinator. Vaccine should not be given to patients with:

  • A confirmed anaphylactic reaction to a previous dose of the vaccine.
  • A confirmed anaphylactic reaction to any component of the vaccine.
  • A confirmed anaphylactic hypersensitivity to egg products, as the vaccines are prepared in hens' eggs. Egg-free vaccine is available if needed.

A careful history should rule out previous non-life-threatening reactions (eg, rash, or reactions which were not truly anaphylactic). Seek the advice of a specialist when in doubt.

In addition, Fluenz® (live attenuated vaccine) is contra-indicated for those who:[7] 

  • Are clinically severely immunodeficient secondary to a condition or immunosuppressive therapy - eg, leukaemias, HIV (not on highly active antiretroviral therapy - HAART) and high-dose corticosteroids.
  • Are receiving salicylate therapy.
  • Are severely asthmatic (level 4 or above) or actively wheezing at the time of vaccination.
  • Intercurrent illness - vaccination may be postponed in the event of an acute illness, but minor illness without pyrexia or systemic upset should not be a reason for delay.
  • Premature infants - at-risk premature infants should have vaccination at the appropriate chronological age, preferably with thiomersal-free vaccine.
  • HIV infection - immunosuppressed patients should be given the vaccine, irrespective of CD4 count. A full antibody response may not be produced. See above also for Fluenz®.

NB: side-effects may be more pronounced if both seasonal influenza and swine influenza vaccinations are co-administered.

  • Angio-oedema, urticaria, bronchospasm and anaphylaxis can occur. This is an immediate reaction, usually due to hypersensitivity to residual egg protein.
  • Neuralgia, paraesthesiae, convulsions and transient thrombocytopenia have been reported rarely.[1]
  • Guillain-Barré syndrome has been reported very rarely (1-2 cases per million vaccinated people).[8] 
  • Encephalomyelitis, neuritis (mainly optic) and vasculitis have also been reported very rarely but a definitie causal relationship with influenza vaccine has not been established.
  • All suspected reactions in children and severe suspected reactions in adults should be reported using the Yellow Card Scheme to the Commission on Human Medicines.[9]
The National Institute for Health and Care Excellence (NICE) has recommended that zanamivir and oseltamivir can be used for the prevention and treatment of influenza - but are not a substitute for vaccination.[1][10] See the separate related article on Influenza.

Further reading & references

  1. Immunisation against infectious disease - the Green Book (latest edition); Public Health England
  2. Jefferson T, Di Pietrantonj C, Al-Ansary LA, et al; Vaccines for preventing influenza in the elderly. Cochrane Database Syst Rev. 2010 Feb 17;(2):CD004876. doi: 10.1002/14651858.CD004876.pub3.
  3. British National Formulary
  4. Seasonal Influenza Vaccine Uptake amongst GP Patient Groups in England 2010/11; Dept of Health, September 2011
  5. Chor JS, Pada SK, Stephenson I, et al; Seasonal influenza vaccination predicts pandemic H1N1 vaccination uptake among Vaccine. 2011 Oct 6;29(43):7364-9. Epub 2011 Jul 30.
  6. Daugherty EL, Speck KA, Rand CS, et al; Perceptions and influence of a hospital influenza vaccination policy. Infect Control Hosp Epidemiol. 2011 May;32(5):449-55.
  7. Summary of Product Characteristics (SPC) - Fluenz® nasal spray suspension Influenza vaccine (live attenuated nasal); AstraZeneca UK. Updated August 2012.
  8. Fiore AE, Bridges CB, Cox NJ; Seasonal influenza vaccines. Curr Top Microbiol Immunol. 2009;333:43-82. doi: 10.1007/978-3-540-92165-3_3.
  9. On-line reporting site for the Yellow Card Scheme; Medicines and Healthcare products Regulatory Agency (MHRA)
  10. Amantadine, oseltamivir and zanamivir for the treatment of influenza; NICE Technology Appraisal, February 2009

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Laurence Knott
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Last Checked:
Document ID:
342 (v11)