ABSTRACT
Two methodologies are used for describing and estimating influenza-related mortality: Individual-based methods, which use death certification and laboratory diagnosis and predominately determine patterns and risk factors for mortality, and population-based methods, which use statistical and modelling techniques to estimate numbers of premature deaths. The total numbers of deaths generated from the two methods cannot be compared. The former are prone to underestimation, especially when identifying influenza-related deaths in older people. The latter are cruder and have to allow for confounding factors, notably other seasonal infections and climate effects. There is no routine system estimating overall European influenza-related premature mortality, apart from a pilot system EuroMOMO. It is not possible at present to estimate the overall influenza mortality due to the 2009 influenza pandemic in Europe, and the totals based on individual deaths are a minimum estimate. However, the pattern of mortality differed considerably between the 2009 pandemic in Europe and the interpandemic period 1970 to 2008, with pandemic deaths in 2009 occurring in younger and healthier persons. Common methods should be agreed to estimate influenza-related mortality at national level in Europe, and individual surveillance should be instituted for influenza-related deaths in key groups such as pregnant women and children.
Subject(s)
Influenza, Human/mortality , Pandemics , Population Surveillance/methods , Adult , Age Distribution , Age Factors , Aged , Cause of Death , Child , Death Certificates , Europe/epidemiology , Female , Health Surveys , Humans , Influenza A Virus, H1N1 Subtype/isolation & purification , Influenza, Human/diagnosis , Influenza, Human/epidemiology , Male , Outcome Assessment, Health Care , Pandemics/statistics & numerical data , Pregnancy , Pregnancy Complications, Infectious/mortality , Risk Factors , SeasonsABSTRACT
The 2011 influenza season (May to October) in the southern hemisphere was dominated by the A(H1N1) viruses that emerged during the 2009 influenza A(H1N1) pandemic and influenza B viruses, although the proportion of these two varied between and within countries. Some influenza A(H3N2) viruses were also seen. We discuss here the preliminary implications for Europe of the 2011 influenza season in five temperate southern hemisphere countries.
