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Case-based reported mortality associated with laboratory-confirmed influenza A(H1N1) 2009 virus infection in the Netherlands: the 2009-2010 pandemic season versus the 2010-2011 influenza season.

van Gageldonk-Lafeber RA, Riesmeijer RM, Friesema IH, Meijer A, Isken LD, Timen A, van der Sande MA - BMC Public Health (2011)

Bottom Line: During the pandemic season, the population mortality rates peaked in persons aged 0-15 and 55-64 years.During the 2010-2011 influenza season, the height of first peak was lower compared to that during the pandemic season.Underlying immunological disorders were more common in the pandemic season compared to the 2010-2011 season (p = 0.02), and cardiovascular disorders were more common in the 2010-2011 season (p = 0.005).

View Article: PubMed Central - HTML - PubMed

Affiliation: National Institute for Public Health and the Environment, RIVM, Centre for Infectious Disease Control, Bilthoven, the Netherlands. rianne.van.gageldonk@rivm.nl

ABSTRACT

Background: In contrast to seasonal influenza epidemics, where the majority of deaths occur amongst elderly, a considerable part of the 2009 pandemic influenza related deaths concerned relatively young people. In the Netherlands, all deaths associated with laboratory-confirmed influenza A(H1N1) 2009 virus infection had to be notified, both during the 2009-2010 pandemic season and the 2010-2011 influenza season. To assess whether and to what extent pandemic mortality patterns were reverting back to seasonal patterns, a retrospective analyses of all notified fatal cases associated with laboratory-confirmed influenza A(H1N1) 2009 virus infection was performed.

Methods: The notification database, including detailed information about the clinical characteristics of all notified deaths, was used to perform a comprehensive analysis of all deceased patients with a laboratory-confirmed influenza A(H1N1) 2009 virus infection. Characteristics of the fatalities with respect to age and underlying medical conditions were analysed, comparing the 2009-2010 pandemic and the 2010-2011 influenza season.

Results: A total of 65 fatalities with a laboratory-confirmed influenza A(H1N1) 2009 virus infection were notified in 2009-2010 and 38 in 2010-2011. During the pandemic season, the population mortality rates peaked in persons aged 0-15 and 55-64 years. In the 2010-2011 influenza season, peaks in mortality were seen in persons aged 0-15 and 75-84 years. During the 2010-2011 influenza season, the height of first peak was lower compared to that during the pandemic season. Underlying immunological disorders were more common in the pandemic season compared to the 2010-2011 season (p = 0.02), and cardiovascular disorders were more common in the 2010-2011 season (p = 0.005).

Conclusions: The mortality pattern in the 2010-2011 influenza season still resembled the 2009-2010 pandemic season with a peak in relatively young age groups, but concurrently a clear shift toward seasonal patterns was seen, with a peak in mortality in the elderly, i.e. ≥ 75 years of age.

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Population mortality rates for laboratory-confirmed influenza A(H1N1) 2009 virus infection per 100, 000 persons for the pandemic season 2009-2010 and the following season 2010-2011.
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Figure 1: Population mortality rates for laboratory-confirmed influenza A(H1N1) 2009 virus infection per 100, 000 persons for the pandemic season 2009-2010 and the following season 2010-2011.

Mentions: The mean age of the deceased patients in 2009/2010 was lower compared to that in 2010/2011, respectively 41 and 53 years (p = 0.02). Figure 1 shows the mortality rate per age group based on the total Dutch population in 2009 and 2010. During the pandemic season, the population mortality rates peaked in children aged between 0 and 15 years of age and in persons aged between 55 and 64 years. In the 2010-2011 influenza season, the first peak was considerably lower, while the second peak shifted to persons aged between 75 and 84 years.


Case-based reported mortality associated with laboratory-confirmed influenza A(H1N1) 2009 virus infection in the Netherlands: the 2009-2010 pandemic season versus the 2010-2011 influenza season.

van Gageldonk-Lafeber RA, Riesmeijer RM, Friesema IH, Meijer A, Isken LD, Timen A, van der Sande MA - BMC Public Health (2011)

Population mortality rates for laboratory-confirmed influenza A(H1N1) 2009 virus infection per 100, 000 persons for the pandemic season 2009-2010 and the following season 2010-2011.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3198709&req=5

Figure 1: Population mortality rates for laboratory-confirmed influenza A(H1N1) 2009 virus infection per 100, 000 persons for the pandemic season 2009-2010 and the following season 2010-2011.
Mentions: The mean age of the deceased patients in 2009/2010 was lower compared to that in 2010/2011, respectively 41 and 53 years (p = 0.02). Figure 1 shows the mortality rate per age group based on the total Dutch population in 2009 and 2010. During the pandemic season, the population mortality rates peaked in children aged between 0 and 15 years of age and in persons aged between 55 and 64 years. In the 2010-2011 influenza season, the first peak was considerably lower, while the second peak shifted to persons aged between 75 and 84 years.

Bottom Line: During the pandemic season, the population mortality rates peaked in persons aged 0-15 and 55-64 years.During the 2010-2011 influenza season, the height of first peak was lower compared to that during the pandemic season.Underlying immunological disorders were more common in the pandemic season compared to the 2010-2011 season (p = 0.02), and cardiovascular disorders were more common in the 2010-2011 season (p = 0.005).

View Article: PubMed Central - HTML - PubMed

Affiliation: National Institute for Public Health and the Environment, RIVM, Centre for Infectious Disease Control, Bilthoven, the Netherlands. rianne.van.gageldonk@rivm.nl

ABSTRACT

Background: In contrast to seasonal influenza epidemics, where the majority of deaths occur amongst elderly, a considerable part of the 2009 pandemic influenza related deaths concerned relatively young people. In the Netherlands, all deaths associated with laboratory-confirmed influenza A(H1N1) 2009 virus infection had to be notified, both during the 2009-2010 pandemic season and the 2010-2011 influenza season. To assess whether and to what extent pandemic mortality patterns were reverting back to seasonal patterns, a retrospective analyses of all notified fatal cases associated with laboratory-confirmed influenza A(H1N1) 2009 virus infection was performed.

Methods: The notification database, including detailed information about the clinical characteristics of all notified deaths, was used to perform a comprehensive analysis of all deceased patients with a laboratory-confirmed influenza A(H1N1) 2009 virus infection. Characteristics of the fatalities with respect to age and underlying medical conditions were analysed, comparing the 2009-2010 pandemic and the 2010-2011 influenza season.

Results: A total of 65 fatalities with a laboratory-confirmed influenza A(H1N1) 2009 virus infection were notified in 2009-2010 and 38 in 2010-2011. During the pandemic season, the population mortality rates peaked in persons aged 0-15 and 55-64 years. In the 2010-2011 influenza season, peaks in mortality were seen in persons aged 0-15 and 75-84 years. During the 2010-2011 influenza season, the height of first peak was lower compared to that during the pandemic season. Underlying immunological disorders were more common in the pandemic season compared to the 2010-2011 season (p = 0.02), and cardiovascular disorders were more common in the 2010-2011 season (p = 0.005).

Conclusions: The mortality pattern in the 2010-2011 influenza season still resembled the 2009-2010 pandemic season with a peak in relatively young age groups, but concurrently a clear shift toward seasonal patterns was seen, with a peak in mortality in the elderly, i.e. ≥ 75 years of age.

Show MeSH
Related in: MedlinePlus