Professional Reference 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).
For the 2015/16 season children aged 2, 3 and 4 years and all children in school years 1 and 2 are also included in the routine programme.
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.
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.
- 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.
- 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.
Method of administration
- 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.
- 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.
- 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.
The percentage uptake for patients aged 65 years and over in England in 2013/2014 was 73%. Vaccine uptake in risk groups aged under 65 years was approximately 52% in England.
Storage, presentation and disposal
- 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.Dispose of the vaccination equipment in a sealable, puncture-proof sharps box (UN-approved BN7390).
Types of vaccine
Most of the currently available vaccines are grown in embryonic hens' eggs and then chemically inactivated and purified. There are three types available:
- '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. 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.
Dosage and schedule
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 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 (including HIV infection, regardless of CD4 count) should be given influenza vaccine in accordance with the recommendations below. They 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 inactivated trivalent vaccine and not live vaccine.
Recommendations for use
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 (JCVI) recommended that the programme should be extended to all children aged 2 to 16 years. The phased introduction of this extension began in 2013 with the inclusion of children aged 2 and 3 years in the routine programme. In the 2015/16 flu season, flu vaccine should be offered to all children who are 2, 3 and 4 years old on 31 August 2015 and to all children of school years 1 and 2 age.
|Clinical risk groups||Examples (decision based on clinical judgement)|
|Chronic respiratory disease|
|Chronic heart disease|
|Chronic liver disease|
|Chronic neurological disease|
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 Pneumococcal Vaccination article), 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 and 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.
Contra-indications to all influenza vaccinations
There are few contra-indications.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.
Egg allergy: a confirmed anaphylactic hypersensitivity to egg products, as the vaccines are prepared in hens' eggs. It has now been advised that, except for those with severe anaphylaxis to egg, which has previously required intensive care, children with an egg allergy can be safely vaccinated with Fluenz Tetra®. An egg-free vaccine is available and can be given.
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:
- 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.
- Guillain-Barré syndrome has (very rarely) been reported (1-2 cases per million vaccinated people).
- Encephalomyelitis, neuritis (mainly optic) and vasculitis have also (very rarely) been reported but a definite 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.
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Further reading & references
- Flu Plan Winter 2015/16; Public Health England, Dept of Health, NHS England
- The national flu immunisation programme 2015/16 - training for healthcare professionals; Public Health England
- Immunizations - seasonal influenza; NICE CKS, February 2015 (UK access only)
- Turner PJ, Southern J, Andrews NJ, et al; Safety of live attenuated influenza vaccine in atopic children with egg allergy. J Allergy Clin Immunol. 2015 Aug 136(2):376-81. doi: 10.1016/j.jaci.2014.12.1925. Epub 2015 Feb 13.
- Influenza: the Green Book, Chapter 19; Public Health England (August 2015)
- 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.
- British National Formulary; NICE Evidence Services (UK access only)
- Chor JS, Pada SK, Stephenson I, et al; Seasonal influenza vaccination predicts pandemic H1N1 vaccination uptake among healthcare workers in three countries. Vaccine. 2011 Oct 6 29(43):7364-9. Epub 2011 Jul 30.
- 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.
- Summary of Product Characteristics (SPC) - Fluenz® nasal spray suspension Influenza vaccine (live attenuated nasal); AstraZeneca UK. Updated August 2015.
- 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.
- Online reporting site for the Yellow Card Scheme; Medicines and Healthcare products Regulatory Agency (MHRA)
- Amantadine, oseltamivir and zanamivir for the treatment of influenza; NICE Technology Appraisal Guidance, February 2009
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