Clinical Notes : Pharmacology

172. Seasonal influenza vaccination

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The objectives of the influenza immunisation programme are to protect those who are most at risk of serious illness or death should they develop influenza and to reduce transmission of the infection, thereby contributing to the protection of vulnerable patients who may have a suboptimal response to their own immunisations

Influenza vaccine should be offered, ideally before influenza viruses start to circulate, to:

  • all those aged 65 years or older (for definition please see the annual flu letter for the coming/current season)

  • all those aged 6 months or older in the clinical risk groups shown in the table below​


  • children not in clinical risk groups that are eligible for vaccination as part of the ongoing phased roll out of the extension of the programme to all children aged 2 to less than 17 years old


Offer vaccination from early October, and continue for the duration of the influenza season.

Children aged 6 months through 8 years who need two doses should get their first dose at the earliest opportunity so they can receive the second dose, which must be given at least 4 weeks later, by the end of October.


Clinical risk groups who should receive the influenza immunisation.

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Other groups

The list above is not exhaustive, and the medical practitioner should apply clinical judgment to take into account the risk of influenza exacerbating any underlying disease that a patient may have, as well as the risk of serious illness from influenza itself

Vaccination should also be offered to household contacts of immunocompromised individuals, i.e. individuals who expect to share living accommodation on most days over the winter and therefore for whom continuing close contact is unavoidable. This may include carers (see below)

In addition to the above, immunisation should be provided to healthcare and social care workers in direct contact with patients/clients to protect them and to reduce the transmission of influenza within health and social care premises, to contribute to the protection of individuals who may have a suboptimal response to their own immunisations, and to avoid disruption to services that provide their care.


This would include:

  • health and social care staff directly involved in the care of their patients or clients


  • 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 of an elderly or disabled person whose welfare may be at risk if the carer falls ill. Vaccination should be given on an individual basis at the GP’s discretion in the context of other clinical risk groups in their practice


  • others involved directly in delivering health and social care such that they and vulnerable patients/clients are at increased risk of exposure to influenza (further information is provided in guidance from UK health departments)

The key changes to the vaccines available for the 2019/20 flu season are:


1. All those aged 65 years and over

  • Three vaccines are available

    • The adjuvanted trivalent inactivated influenza vaccine (aTIV) introduced in 2018/19

    • The Quadrivalent influenza cell culture vaccine (IVc), licensed in December 2018

    • The high-dose trivalent inactivated influenza vaccine (TIV-HD), licensed in January 2019


  • Evidence suggests that these three vaccines are all superior to standard egg-based inactivated trivalent and quadrivalent vaccines (


  • TIVe/QIVe) in terms of effectiveness for those aged 65 years and over


  • There is not enough data accumulated to express a preference for the use of any single vaccine to date, therefore all three are advised for use in 2019/20

2. Adults aged 18 to under 65 years old in clinical risk groups (including pregnant women and all health care workers in this age group)


  • Two vaccines will be licenced and available

    • The egg grown quadrivalent inactivated influenza vaccine (QIVe)

    • The newly licenced quadrivalent influenza cell culture vaccine (QIVc)


  • Overall there is not enough data accumulated to express a preference for the use of either vaccine in this age group. Therefore both will be recommended and available for use in 2019/20


Inform people you vaccinate that after immunisation

it may take up to 14 days to achieve protective immune responses



  • The inactivated influenza vaccines should normally be given into the upper arm (or anterolateral thigh in infants) preferably by intramuscular injection. Influenza vaccines licensed for intramuscular or subcutaneous administration may alternatively be administered by the subcutaneous route


  • Individuals on stable anticoagulation therapy, including individuals on warfarin who are up-to-date with their scheduled International Normalised Ratio (INR) testing and whose latest INR was below the upper threshold of their therapeutic range, can receive intramuscular vaccination

    • a fine needle (23 or 25 gauge) should be used for the vaccination, followed by firm pressure applied to the site (without rubbing) for at least 2 minutes

    • if in any doubt, consult with the clinician responsible for prescribing or monitoring the individual’s anticoagulant therapy


  • Individuals with bleeding disorders may be vaccinated intramuscularly if, in the opinion of a doctor familiar with the individual’s bleeding risk, vaccines or similar small volume intramuscular injections can be administered with reasonable safety by this route

    • a fine needle (23 or 25 gauge) should be used for the vaccination, followed by firm pressure applied to the site (without rubbing) for at least 2 minutes

    • the individual/parent/carer should be informed about the risk of haematoma from the injection


  • The live attenuated influenza vaccine (LAIV) is administered by the intranasal route (Fluenz Tetra®) and is supplied in an applicator that allows a divided dose to be administered in each nostril (total dose of 0.2 ml, 0.1 ml in each nostril):

    • administration of either dose does not need to be repeated if the patient sneezes or blows their nose following administration

    • as heavy nasal congestion might impede delivery of the vaccine to the nasopharyngeal mucosa, deferral of administration until resolution of the nasal congestion should be considered, or if appropriate, an alternative intramuscularly administered influenza vaccine


  • Inactivated influenza vaccines can be given at the same time as other vaccines. LAIV can also be given at the same time as other live or inactivated vaccines


  • Intramuscular and intradermal vaccines should be given at separate sites, preferably in a different limb. If given in the same limb, they should be given at least 2.5 cm apart


  • After immunisation, protective immune responses may be achieved within 14 days


  • influenza activity is not usually significant in the UK (and ROI) before the middle of November, the influenza season can start early, therefore the ideal time for immunisation is between September and early November

Influenza vaccines for the 2019/20 influenza season



  • The summaries of product characteristics for individual products should always be referred to when deciding which vaccine to give.

There are very few individuals who cannot receive any influenza vaccine.

When there is doubt, appropriate advice should be sought promptly from the screening and immunisation team in the NHS England area team, a consultant in communicable disease control or a consultant paediatrician, so that the period the individual is left unvaccinated is minimised


  • None of the influenza vaccines should be given to those who have had:

  • a confirmed anaphylactic reaction to a previous dose of the vaccine, or

  • a confirmed anaphylactic reaction to any component of the vaccine (other than ovalbumin—see the precautions section of the full guideline)


Children 2 years through 4 years who have asthma or who have had a history of wheezing in the past 12 months should not get the

nasal spray vaccine.

People of any age with asthma might be at increased risk for wheezing after getting the nasal spray flu vaccine.


Adverse reactions


  • Pain, swelling or redness at the injection site, low grade fever, malaise, shivering, fatigue, headache, myalgia and arthralgia are among the commonly reported symptoms after intramuscular or intradermal vaccination

  • A small painless nodule (induration) may also form at the injection site. These symptoms usually disappear within one to two days without treatment. Nasal congestion/rhinorrhoea, reduced appetite, weakness, and headache are common adverse reactions following administration of LAIV

  • Immediate reactions such as urticaria, angio-oedema, bronchospasm, and anaphylaxis can occur


Summary of influenza immunisation guidance

Guidelines in Practice

3 May 2019



Influenza vaccines for the 2019-20 season (UK)

Public Health England. Gov.UK

January 2019 update

Flu vaccination: increasing uptake

NICE guideline [NG103]

Published date: August 2018


Influenza: the green book, chapter 19


Published 20 March 2013
Last updated 23 April 2019


Influenza (Flu). 

Centers for Disease Control and Prevention (CDC).

June 2019.


Recommendations for Prevention and Control of Influenza in Children, 2018–2019

Committee on Infectious Diseases, American Academy of Pediatrics


October 2018, VOLUME 142 / ISSUE 4


Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenza.

Uyeki TM, Bernstein HH, Bradley JS, et al.

Clin Infect Dis. 2018 Dec 19.


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