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Vaccines are the leading pharmacological measure for limiting the impact of pandemic influenza in the community.15
While pandemic influenza vaccines are only available some months after an outbreak starts, seasonal influenza vaccinations are developed each year. Candidate pandemic vaccines are also available for particular strains.
Seasonal influenza vaccination will not protect an individual against a pandemic influenza strain; however, it can reduce circulating influenza virus in the community and the chances that seasonal influenza will be confused with an outbreak of a novel strain.
Seasonal influenza vaccination is encouraged according to the current immunisation guidelines as outlined in the National Health and Medical Research Council (NHMRC)’s Immunisation handbook (10th edition).
Influenza vaccine is the only vaccine reformulated each year to optimise the match between vaccine and circulating virus strains. The WHO issues recommendations for the different strains of influenza viruses (type A and type B) which are included in the vaccine based on the prevailing strains in the northern and southern hemispheres. Once the recommendation is made, vaccine producers require at least 6 months to manufacture and distribute the vaccine.16 Unfortunately, not all influenza vaccines (especially influenza A) have high vaccine effectiveness.17
In the case of pandemic influenza, once the viral strain has been identified it takes at least 3–6 months for vaccination development.
The development of a vaccine that could block all strains of influenza virus is an intense area of research. There have been some promising leads but there is no vaccine for the foreseeable future.18