Due to the weekly report of the EISS (European Influenza Surveillance Scheme) the total number of positive specimens has steadily increased from less than 100 in week 50/2006 to 626 cases in week 3/2007 and are expected to peak at between 1,000 and 2,000 as the virus will affect more European countries.
This year´s season starts a little bit earlier than the season 2005/2006, which had its high-level period from mid-February to late April. In contrast to last year, most of the cases reported to the EISS were tested positive for influenza A H3, the more virulent compared to influenza B. Influenza A has 2 subtypes which are important for humans: A(H3N2) and A(H1N1), of which the former is currently associated with most deaths.
In annual influenza epidemics 5-15% of the population are affected with upper respiratory tract infections. Hospitalization and deaths mainly occur in high-risk groups (elderly, chronically ill).
Therefore the WHO recommends that “elderly persons, and persons of any age who are considered at “high risk” for influenza-related complications due to underlying health conditions, should be vaccinated. Among the elderly, vaccination is thought to reduce influenza-related morbidity by 60% and influenza-related mortality by 70-80%. Among healthy adults the vaccine is very effective (70-90%) in terms of reducing influenza morbidity, and vaccination has been shown to have substantial health-related and economic benefits in this age group. The effectiveness of influenza vaccine depends primarily on the age and immunocompetence of the vaccine recipient and the degree of similarity between the viruses in the vaccine and those in circulation. Influenza vaccination can reduce both health-care costs and productivity losses associated with influenza illness.”
Further information: http://www.eiss.org/index.cgi