WHO Consultation on Applying Surveillance Information in the Tropics and Subtropics
Bangkok, Thailand, 26–28 April 2016
The historical and continuing under-use of seasonal influenza vaccines in low- and middle-income countries, particularly in the tropics and subtropics, increasingly represents a missed opportunity to substantially reduce associated disease and economic burdens. Renewed efforts are now needed to greatly expand access to seasonal influenza vaccines in such settings, particularly among key groups at high risk such as pregnant women. The current consultation was the culmination of a series of meetings and related WHO activities intended to support countries in tropical and subtropical regions looking to introduce or expand national seasonal influenza vaccination programmes.
Despite differences in the timing and patterns of influenza seasonality in the tropics and subtropics, there is no evidence to suggest that the predominantly circulating viruses differ from those seen in temperate zones. As the same influenza viruses appear to circulate globally there would appear to be no need for a special seasonal vaccine to be produced for the tropics and subtropics. There is growing consensus that tropical and subtropical countries should instead use the most recent vaccine (northern or southern hemisphere) that best matches national patterns of seasonality and is available 2–3 months prior to the peak of the influenza season. However, despite significant capacity-building efforts in recent years, many countries still lack sufficient surveillance data, both epidemiological and virological, to inform decisions on which of the two biannual WHO-recommended vaccine compositions to use and when.