Increasing influenza activity in the WHO European Region

WHO/Europe, in collaboration with the European Commission and the European Centre for Disease Prevention and Control, is closely monitoring influenza activity in the Region. Influenza activity is increasing, most notably in the north-western part of the Region. This season, the most prevalent viruses have been pandemic (H1N1) 2009 and influenza B, with relatively few influenza A(H3N2) viruses being detected. In addition, several countries have reported severe and fatal cases and the burden of severe influenza has been sufficient to place considerable strain on critical care services in two western European countries. While most severe influenza cases are associated with influenza A(H1N1) 2009 virus infections, a smaller number of severe influenza B virus infections are also being reported.

As explained in the WHO Director-General’s post-pandemic announcement in August 2010, the pandemic A(H1N1) 2009 virus was expected to continue to circulate and cause local outbreaks and epidemics, as well as severe disease and deaths both in recognized higher-risk groups and in previously healthy people. Available evidence indicates that groups identified during the pandemic as at high risk for severe or fatal illness remain at heightened risk, and that most of the fatal cases had not been vaccinated.

The H1N1 2009 virus circulating in Europe corresponds with the strain included in the vaccine for the 2010/2011 season in the northern hemisphere. WHO/Europe recommends that health ministries ensure high rates of uptake of seasonal influenza vaccine by individuals who might be at risk of developing complications. In particular, authorities should reach out to pregnant women, as seasonal influenza vaccination campaigns have not traditionally targeted this group. Health care workers need to be motivated to vaccinate themselves, and mobilized to help boost vaccine acceptance among individuals at risk for severe disease. Lessons learned over the past 12–18 months show that health care workers play a significant role in communities’ response to influenza.

WHO also advises national authorities to start or enhance awareness-raising activities among individuals at risk for complications from influenza, emphasizing their need to seek medical advice or care early in the course of infection. In addition, governments need to alert family doctors, hospitals and intensive care units to the expected increase in influenza patients, so that they can start triage and early treatment of pneumonia patients, especially in resource-poor environments. Clinicians should start treatment for influenza when they suspect the illness, without relying on rapid diagnostic tests or waiting for laboratory confirmation.