Assessment of Effectiveness of the Influenza Vaccine for the Season 2016/2017 in US
Published on 2 August 2016
Vaccination is the most effective way to prevent infection with seasonal influenza viruses. Generally, the World Health Organization (WHO) recommends the vaccine for the Northern Hemisphere in February and production begins once the FDA approves it. Evolution of influenza viruses between the time of vaccine selection and the beginning of the flu season (week 40 for the Northern Hemisphere) can seriously hamper vaccine efficacy. For this reason, in most years, the flu vaccine is 50% to 70% effective. The meta-analysis of 56 studies showed persistently low flu vaccine effectiveness for the H3N2 strain over multiple seasons1. According to this analysis, effectiveness against H3N2 for antigenically matched viruses was 33% and for variant viruses was 23%. This result shows that the current approach, which is based on the structural compatibility between antigens of vaccine and circulating influenza viruses, is not efficient accurate enough to provide a highly effective seasonal flu vaccine.
Recently, it was propose a new bioinformatics approach for analysis of influenza viruses which could be used as an efficient tool for selection of vaccine viruses, assessment of the effectiveness of seasonal influenza vaccines, and prediction of the epidemic/pandemic potential of novel influenza viruses2. We compared using this bioinformatics tool hemagglutinin from all human H3N2 influenza viruses isolated in US in the period March-July 20163 and the H3N2 virus A/Hong Kong/4801/2014 which is selected by WHO as the vaccine virus for the 2016/2017 flu season.
Results of the ISM-based phylogenetic analysis2 presented in Figure 1 show that 306 analyzed H3N2 viruses are clusterized in two groups: group A and group B which encompasses 218 (71%) and 88 (29%) viruses, respectively. The vaccine virus A/Hong Kong/4801/2014 belongs to the smallest group B, suggesting that vaccine will be efficient against viruses from this group but not from the group A.
Figure 1. The ISM-base phylogenetic analysis of H3N2 influenza viruses isolated in US in the period March-July 2016.
(Figure 1 in high resolution)
This result indicates that
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