Influenza

Peer-reviewed literature

07 October 2011

Influenza vaccination is recognized as the most effective method of influenza prevention, but influenza vaccines are currently not available to most of the world’s populations. National level evidence-based decision making about policies for the use of influenza vaccines among different age groups is, ideally, based on estimates of the potential impact of proposed influenza vaccine programs. Dawood et al. (2011) use Thailand as a case-study to present a model that uses surveillance data, published vaccine effectiveness estimates, and vaccination coverage assumptions to estimate the impact of influenza vaccination on pediatric influenza pneumonia hospitalizations.

Since 2007, the Thailand Ministry of Public Health has recommended the use of, and subsidized, influenza vaccination for adults aged 65 years and older. Surveillance data presented from 20 hospitals in two Thai provinces was extrapolated to estimate the average number of clinical pneumonia hospitalizations across the country. Nationally, influenza was estimated to result in 12–42 hospitalizations for clinical pneumonia per 100,000 persons, with 52% of these hospitalizations occurring in children aged less than 15 years; based on results in the current paper, 53,133 (range 44,137-65,258) hospitalizations for influenza pneumonia occur among children 7 months to 17 years of age, 56% of which is in children 7 months to 4 years of age. The methodology in this paper indicates that expansion of the Thai influenza vaccination program to include children 7 months to 4 years of age, with coverage similar to that for other vaccines, could prevent up to 30% of all pediatric influenza pneumonia hospitalizations, and prevent one hospitalization for every 210 doses of influenza vaccine administered.

Comment:

This paper highlights the use of surveillance data for informing public policy decisions. Using a well-designed surveillance system, and relatively simple models, the authors are able to use their data to estimate the potential public health impact of implementing an intervention to prevent influenza. This model can easily be applied in other countries that have hospital-based surveillance systems to estimate the burden of influenza-related hospitalizations, and importantly, incorporate measures of the uncertainty of such estimates, including the sensitivity and specificity of laboratory confirmation of influenza.

Reference:

Dawood, F.S. et al. A method for estimating vaccine-preventable pediatric influenza pneumonia hospitalizations in developing countries: Thailand as a case study Original Research Article. Vaccine; 29(26): 4416-4421.

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