Abstract
BackgroundVaccination is generally considered to be the best primary prevention measure against influenza virus infection. Many countries encourage specific target groups of people to undertake vaccination, often with financial subsidies or a priority list. To understand differential patterns of national target groups for influenza vaccination before, during and after the 2009 influenza pandemic, we reviewed and analyzed the country-specific policies in the corresponding time periods.MethodsInformation on prioritized groups targeted to receive seasonal and pandemic influenza vaccines was derived from a multi-step internet search of official health department websites, press releases, media sources and academic journal articles. We assessed the frequency and consistency of targeting 20 different groups within populations which are associated with age, underlying medical conditions, role or occupations among different countries and vaccines. Information on subsidies provided to specific target groups was also extracted.ResultsWe analyzed target groups for 33 (seasonal 2009 and 2009-10 vaccines), 72 (monovalent pandemic 2009-10 vaccine) and 34 (seasonal 2010 and 2010-11 vaccines) countries. In 2009-10, the elderly, those with chronic illness and health care workers were common targets for the seasonal vaccine. Comparatively, the elderly, care home residents and workers, animal contacts and close contacts were less frequently targeted to receive the pandemic vaccine. Pregnant women, obese persons, essential community workers and health care workers, however, were more commonly targeted. After the pandemic, pregnant women, obese persons, health care and care home workers, and close contacts were more commonly targeted to receive the seasonal vaccine compared to 2009-10, showing continued influence from the pandemic. Many of the countries provided free vaccines, partial subsidies, reimbursements or national health insurance coverage to specific target groups and over one-third of the countries offered universal subsidy regarding the pandemic vaccine. There was also some inconsistency between countries in target groups.ConclusionsDifferences in target groups between countries may reflect variable objectives as well as uncertainties regarding the transmission dynamics, severity and age-specific immunity against influenza viruses before and after vaccination. Clarification on these points is essential to elucidate optimal and object-oriented vaccination strategies.
Highlights
Vaccination is generally considered to be the best primary prevention measure against influenza virus infection
In the pandemic it was reported that existing seasonal influenza vaccinations including the 2009-10 trivalent seasonal influenza vaccine were not likely to provide substantial protection against the pandemic H1N1 virus, while the prevalence of pre-existing cross-reactive antibody against pH1N1, likely indicative of some degree of protection against infection, was very low in most age groups except the elderly [7]
To investigate differential patterns of vaccination targets and subsidy by different vaccines and countries, we report and compare groups targeted in different regions of the world to receive the monovalent pH1N1 vaccine, the 2009 (Southern Hemisphere) and 2009-10 (Northern Hemisphere) seasonal vaccines which included a seasonal A/Brisbane/59/2007(H1N1)like virus, and the post-pandemic seasonal vaccines in 2010 and 2010-11 that included a A/California/7/2009 (H1N1)-like virus
Summary
Vaccination is generally considered to be the best primary prevention measure against influenza virus infection. The World Health Organization (WHO) issues recommendations on influenza vaccine composition in February for the Northern Hemisphere, and September for the Southern Hemisphere. It usually takes around 6 months after the recommendation meeting for the vaccines to become available. In the pandemic it was reported that existing seasonal influenza vaccinations including the 2009-10 trivalent seasonal influenza vaccine were not likely to provide substantial protection against the pandemic H1N1 (pH1N1) virus, while the prevalence of pre-existing cross-reactive antibody against pH1N1, likely indicative of some degree of protection against infection, was very low in most age groups except the elderly [7]. The pH1N1 virus subsequently replaced the seasonal A(H1N1) virus in the 2010 trivalent seasonal influenza vaccine in the Southern Hemisphere, and the 2010-11 trivalent seasonal influenza vaccine in the Northern Hemisphere
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