Comparative community burden and severity of seasonal and pandemic influenza: results of the Flu Watch cohort study

Abstract

Medical Research Council and the Wellcome Trust.

Estimation of influenza‐attributable medically attended acute respiratory illness by influenza type/subtype and age, Germany, 2001/02–2014/15

“…The two child age groups mostly have a rather high attack rate, then it drops and stays rather constant in “younger” adulthood (15‐59 years) before it drops again in old age. Several other population‐based studies or analyses of surveillance data have observed that medically attended respiratory illnesses on primary care level decline with age 1, 21, 22, 23, 24. What this study adds is the additional information of the comprehensive burden of all‐influenza cases in primary care, be they mild or more severe, not only by age, but also by type/subtype, over a long time period.…”

“…Part of the challenge is that influenza cases are both frequent and may present clinically as a variety of syndromes. While the common notion is that influenza presents with fever and systemic symptoms, such as headache or myalgia, it is now well known that a large proportion of influenza disease may present also as a mild form, indistinguishable from the illness caused by other respiratory viruses 1. Thus, syndromic (combined with virological) surveillance systems have been put in place in many countries to monitor intensity and spread of influenza.…”

“…As a result, ILI case definitions are more specific, but less sensitive compared to ARI, and as a corollary surveillance systems using ILI see more pronounced illness waves and peaks during influenza epidemics. However, because only a portion of all symptomatic influenza cases are captured by ILI case definitions,1, 5, 6, 7, 8, 9 ILI surveillance systems are less well suited to describe and capture the burden of disease of influenza.…”

Trivalent and quadrivalent influenza vaccination effectiveness in Australia and South Africa: results from a modelling study

“…The best estimates available6, 9 are based on surveys that correlate serological RNA RT‐PCR testing and prospective community surveillance. However, these studies cover at most 5 years and we have chosen to apply average values from these studies to all 11 years considered in our study.…”

“…estimated an average annual infection rate of 21·5% and a symptomatic attack rate of 3·17% over 3 years (2007, 2008 and 2010); this study gives an estimate in a setting (Vietnam) where no seasonal influenza vaccination was used. Hayward et al 6. estimated an annual infection rate 18%, with 25% of illnesses being asymptomatic, averaged over 5 years (2006–2011).…”