Swine flu vaccination

• prior to the swine flu pandemic, vaccine manufacturers had developed and tested new types of influenza vaccines that could be adapted when a pandemic arose. These monovalent (i.e. single strain) vaccines were developed with antigen from H5N1 influenza viruses - a virus to which most people have no immunity
  • influenza A(H1N1)v vaccines are, therefore, the same as these H5N1 vaccines except that the virus antigen comes from the WHO pandemic declared strain A/California/07/2009
• there are two influenza A(H1N1)v vaccine products available for use in the UK
  • Pandemrix®, manufactured by GlaxoSmithKline, is a split virion, inactivated, adjuvanted vaccine. It is a monovalent vaccine containing 3.75 micrograms of antigen. The antigen used is A/California/07/2009 (H1N1)v-like strain (X-179A), propagated in fertilised hens�' eggs
    • vaccine contains an adjuvant (AS03) to help boost the immune response
  • Celvapan ®, manufactured by Baxter Healthcare, is a whole virion, inactivated, vero cell derived vaccine containing 7.5 micrograms of antigen
    • the antigen used is the wild-type A/California/07/2009 H1N1 strain
    • the whole virion is inactivated both by formaldehyde and UV-irradiation
    • does not contain an adjuvant
  • both vaccines are inactivated, do not contain live viruses and cannot cause flu
  • pregnant women
    • pregnant women should be offered Pandemrix® in preference to Celvapan®
      • this is because a one-dose schedule of Pandemrix® gives adequate levels of antibodies and thereby confers more rapid protection than would be afforded by the two-dose Celvapan® schedule at a time when pandemic influenza viruses are circulating
  • Clinical risk groups who should receive the influenza immunisation

• Notes:
  • some immunocompromised patients may have a suboptimal immunological response to the vaccine
  • the examples within each group are not meant to be an exhaustive and exclusive list. It is not possible to list all conditions likely to be at higher risk. Healthcare practitioners should also use clinical judgement and 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
  • The groups have been prioritised for vaccination in the following order:
    • i. Individuals aged six months and up to 65 years in the clinical at-risk groups (see Table above )
    • ii. All pregnant women
    • iii. Household contacts of immunocompromised individuals
    • iv.Individuals aged 65 years and over in the clinical at-risk groups (see Table above)
  • frontline health and social care workers should also receive the influenza A(H1N1)v vaccine as they are at increased risk of exposure to the virus and increased risk of transmitting the virus to vulnerable patients and to others including their own family members. Frontline staff are those who have regular clinical contact with patients and who are directly involved in patient care

For more detailed guidance then consult the Pandemic influenza A (H1N1) chapter in the Green Book (1).

Reference:

• (1) Department of Health. The Green Book. Pandemic influenza A(H1N1)v 2009.