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The first wave of pandemic influenza (H1N1) 2009 in Germany: from initiation to acceleration.

Poggensee G, Gilsdorf A, Buda S, Eckmanns T, Claus H, Altmann D, RKI Working Group Pandemic InfluenzaKrause G, Haas W - BMC Infect. Dis. (2010)

Bottom Line: Furthermore, young children (0 to 2 years) (OR = 2.8 [95% CI: 1.5; 5.2]) and persons with influenza-like illness (ILI, OR = 1.4 [95% CI: 1.0; 2.1]) had a higher risk to develop pneumonia compared to other age groups and individuals without ILI.The spread of disease did not result in change of risk groups or severity.Our results show that analyses of case-based information can advise future public health measures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Infectious Disease Epidemiology, Robert Koch Institute, DGZ-Ring 1, 13086 Berlin, Germany.

ABSTRACT

Background: The first imported case of pandemic influenza (H1N1) 2009 in Germany was confirmed in April 2009. However, the first wave with measurable burden of disease started only in October 2009. The basic epidemiological and clinical characteristics of the pandemic were analysed in order to understand the course of the pandemic in Germany.

Methods: The analysis was based on data from the case-based, mandatory German surveillance system for infectious diseases. Cases notified between 27 April and 11 November 2009 and fulfilling the case definition were included in the study.

Results: Two time periods with distinct epidemiologic characteristics could be determined: 23,789 cases (44.1%) occurred during the initiation period (IP, week 18 to 41), and 30,179 (55.9%) during the acceleration period (AP, week 42 to 45). During IP, coinciding with school summer holidays, 61.1% of cases were travel-related and one death occurred. Strict containment efforts were performed until week 32. During AP the majority of cases (94.3%) was autochthonous, 12 deaths were reported. The main affected age group shifted from 15 to 19 years in IP to 10 to 14 years in AP (median age 19 versus 15 years; p < 0.001). The proportion of cases with underlying medical conditions increased from 4.7% to 6.9% (p < 0.001). Irrespective of the period, these cases were more likely to be hospitalised (OR = 3.6 [95% CI: 3.1; 4.3]) and to develop pneumonia (OR = 8.1 [95% CI: 6.1; 10.7]). Furthermore, young children (0 to 2 years) (OR = 2.8 [95% CI: 1.5; 5.2]) and persons with influenza-like illness (ILI, OR = 1.4 [95% CI: 1.0; 2.1]) had a higher risk to develop pneumonia compared to other age groups and individuals without ILI.

Conclusion: The epidemiological differences we could show between summer and autumn 2009 might have been influenced by the school summer holidays and containment efforts. The spread of disease did not result in change of risk groups or severity. Our results show that analyses of case-based information can advise future public health measures.

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Activity of acute respiratory illness and school holiday density between week 18 and 45, Germany 2009. Weekly data of Practice index in Germany. Threshold >115. (dotted line) Arbeitsgemeinschaft Influenza, Robert Koch Institute. Light blue columns indicate the vacation density for each week.
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Figure 2: Activity of acute respiratory illness and school holiday density between week 18 and 45, Germany 2009. Weekly data of Practice index in Germany. Threshold >115. (dotted line) Arbeitsgemeinschaft Influenza, Robert Koch Institute. Light blue columns indicate the vacation density for each week.

Mentions: Weeks 18 through 28 were characterised by low numbers of reported cases. From week 29 to 35 an increased number of cases was reported with a peak of more than 3,500 cases in week 31. The peak was followed by a lower plateau with 850 to 1,500 newly reported cases per week (week 36 to 41). From week 42 onwards the number of reported cases started to increase steeply forming the first wave of autochthonous transmission of pandemic influenza (H1N1) 2009 in Germany (figure 1). During the summer no increased influenza activity was detected by the syndromic sentinel surveillance, however, from week 42 onwards the nationwide ARI activity was for the first time above the baseline activity threshold with pronounced increased activity in the southern part of Germany, especially in Bavaria (figure 2).


The first wave of pandemic influenza (H1N1) 2009 in Germany: from initiation to acceleration.

Poggensee G, Gilsdorf A, Buda S, Eckmanns T, Claus H, Altmann D, RKI Working Group Pandemic InfluenzaKrause G, Haas W - BMC Infect. Dis. (2010)

Activity of acute respiratory illness and school holiday density between week 18 and 45, Germany 2009. Weekly data of Practice index in Germany. Threshold >115. (dotted line) Arbeitsgemeinschaft Influenza, Robert Koch Institute. Light blue columns indicate the vacation density for each week.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2902478&req=5

Figure 2: Activity of acute respiratory illness and school holiday density between week 18 and 45, Germany 2009. Weekly data of Practice index in Germany. Threshold >115. (dotted line) Arbeitsgemeinschaft Influenza, Robert Koch Institute. Light blue columns indicate the vacation density for each week.
Mentions: Weeks 18 through 28 were characterised by low numbers of reported cases. From week 29 to 35 an increased number of cases was reported with a peak of more than 3,500 cases in week 31. The peak was followed by a lower plateau with 850 to 1,500 newly reported cases per week (week 36 to 41). From week 42 onwards the number of reported cases started to increase steeply forming the first wave of autochthonous transmission of pandemic influenza (H1N1) 2009 in Germany (figure 1). During the summer no increased influenza activity was detected by the syndromic sentinel surveillance, however, from week 42 onwards the nationwide ARI activity was for the first time above the baseline activity threshold with pronounced increased activity in the southern part of Germany, especially in Bavaria (figure 2).

Bottom Line: Furthermore, young children (0 to 2 years) (OR = 2.8 [95% CI: 1.5; 5.2]) and persons with influenza-like illness (ILI, OR = 1.4 [95% CI: 1.0; 2.1]) had a higher risk to develop pneumonia compared to other age groups and individuals without ILI.The spread of disease did not result in change of risk groups or severity.Our results show that analyses of case-based information can advise future public health measures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Infectious Disease Epidemiology, Robert Koch Institute, DGZ-Ring 1, 13086 Berlin, Germany.

ABSTRACT

Background: The first imported case of pandemic influenza (H1N1) 2009 in Germany was confirmed in April 2009. However, the first wave with measurable burden of disease started only in October 2009. The basic epidemiological and clinical characteristics of the pandemic were analysed in order to understand the course of the pandemic in Germany.

Methods: The analysis was based on data from the case-based, mandatory German surveillance system for infectious diseases. Cases notified between 27 April and 11 November 2009 and fulfilling the case definition were included in the study.

Results: Two time periods with distinct epidemiologic characteristics could be determined: 23,789 cases (44.1%) occurred during the initiation period (IP, week 18 to 41), and 30,179 (55.9%) during the acceleration period (AP, week 42 to 45). During IP, coinciding with school summer holidays, 61.1% of cases were travel-related and one death occurred. Strict containment efforts were performed until week 32. During AP the majority of cases (94.3%) was autochthonous, 12 deaths were reported. The main affected age group shifted from 15 to 19 years in IP to 10 to 14 years in AP (median age 19 versus 15 years; p < 0.001). The proportion of cases with underlying medical conditions increased from 4.7% to 6.9% (p < 0.001). Irrespective of the period, these cases were more likely to be hospitalised (OR = 3.6 [95% CI: 3.1; 4.3]) and to develop pneumonia (OR = 8.1 [95% CI: 6.1; 10.7]). Furthermore, young children (0 to 2 years) (OR = 2.8 [95% CI: 1.5; 5.2]) and persons with influenza-like illness (ILI, OR = 1.4 [95% CI: 1.0; 2.1]) had a higher risk to develop pneumonia compared to other age groups and individuals without ILI.

Conclusion: The epidemiological differences we could show between summer and autumn 2009 might have been influenced by the school summer holidays and containment efforts. The spread of disease did not result in change of risk groups or severity. Our results show that analyses of case-based information can advise future public health measures.

Show MeSH
Related in: MedlinePlus