Estimated MAARI baselines in different age groups for regions of Germany.

<p>Estimated MAARI baselines in different age groups for regions of Germany.</p

(Sensitivity analysis 2) Comparison of estimated total excess MAARI during epidemic periods depending on data of more seasons being available starting from 2006/07 to estimate the MAARI baseline.

<p>(Sensitivity analysis 2) Comparison of estimated total excess MAARI during epidemic periods depending on data of more seasons being available starting from 2006/07 to estimate the MAARI baseline.</p

Estimates of Excess Medically Attended Acute Respiratory Infections in Periods of Seasonal and Pandemic Influenza in Germany from 2001/02 to 2010/11

<div><p>Background</p><p>The number of patients seeking health care is a central indicator that may serve several different purposes: (1) as a proxy for the impact on the burden of the primary care system; (2) as a starting point to estimate the number of persons ill with influenza; (3) as the denominator data for the calculation of case fatality rate and the proportion hospitalized (severity indicators); (4) for economic calculations. In addition, reliable estimates of burden of disease and on the health care system are essential to communicate the impact of influenza to health care professionals, public health professionals and to the public.</p><p>Methodology/Principal Findings</p><p>Using German syndromic surveillance data, we have developed a novel approach to describe the seasonal variation of medically attended acute respiratory infections (MAARI) and estimate the excess MAARI attributable to influenza. The weekly excess inside a period of influenza circulation is estimated as the difference between the actual MAARI and a MAARI-baseline, which is established using a cyclic regression model for counts. As a result, we estimated the highest ARI burden within the last 10 years for the influenza season 2004/05 with an excess of 7.5 million outpatient visits (CI95% 6.8–8.0). In contrast, the pandemic wave 2009 accounted for one third of this burden with an excess of 2.4 million (CI95% 1.9–2.8). Estimates can be produced for different age groups, different geographic regions in Germany and also in real time during the influenza waves.</p></div

Begin and end of the period of influenza circulation per season based on virological data collected by the NRCI, Germany.

<p>Begin and end of the period of influenza circulation per season based on virological data collected by the NRCI, Germany.</p

Estimated total positive and negative excess MAARI [in Million] in epidemic and non-epidemic periods of influenza.

<p>Estimated total positive and negative excess MAARI [in Million] in epidemic and non-epidemic periods of influenza.</p

Estimated total excess MAARI inside epidemic periods as percentage of the population by season and region.

<p>Estimated total excess MAARI inside epidemic periods as percentage of the population by season and region.</p

Prospective estimation of total excess MAARI: Changes after end of epidemic period depending on the data set.

<p>Prospective estimation of total excess MAARI: Changes after end of epidemic period depending on the data set.</p

Course of positivity rate and MAARI in season 2008/09.

<p>(A) Positivity rate of influenza in samples investigated by the NRCI. Weeks of the epidemic period are colored red, whereas all other weeks are green; (B) MAARI incidence in percent of the population of the southern region, in age group (15–34); the black horizontal lines indicate the beginning and end of the epidemic period.</p

(Sensitivity analysis 2) Comparison of estimated MAARI baseline for 5–14 year old children in the southern region depending on the data set used.

<p>(Sensitivity analysis 2) Comparison of estimated MAARI baseline for 5–14 year old children in the southern region depending on the data set used.</p

Projected MAARI (darkgreen) with 95% confidence interval (green) and estimated MAARI baseline (red) with 95% prediction interval (dotted red line) for age group (5–14) in the southern region, starting from season 2006/07, vertical lines indicate beginning and end of epidemic periods.

<p>Projected MAARI (darkgreen) with 95% confidence interval (green) and estimated MAARI baseline (red) with 95% prediction interval (dotted red line) for age group (5–14) in the southern region, starting from season 2006/07, vertical lines indicate beginning and end of epidemic periods.</p