Spatial and temporal characteristics of the 2009 A/H1N1 influenza Pandemic in Peru

Gerardo Chowell, Cécile Viboud, Cesar V. Munayco, Jorge Gómez, Lone Simonsen, Mark A. Miller, James Tamerius, Victor Fiestas, Eric S. Halsey, Victor A. Laguna-Torres

Research output: Contribution to journalArticle

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Abstract

Background: Highly refined surveillance data on the 2009 A/H1N1 influenza pandemic are crucial to quantify the spatial and temporal characteristics of the pandemic. There is little information about the spatial-temporal dynamics of pandemic influenza in South America. Here we provide a quantitative description of the age-specific morbidity pandemic patterns across administrative areas of Peru. Methods: We used daily cases of influenza-like-illness, tests for A/H1N1 influenza virus infections, and laboratory-confirmed A/H1N1 influenza cases reported to the epidemiological surveillance system of Peru's Ministry of Health from May 1 to December 31, 2009. We analyzed the geographic spread of the pandemic waves and their association with the winter school vacation period, demographic factors, and absolute humidity. We also estimated the reproduction number and quantified the association between the winter school vacation period and the age distribution of cases. Results: The national pandemic curve revealed a bimodal winter pandemic wave, with the first peak limited to school age children in the Lima metropolitan area, and the second peak more geographically widespread. The reproduction number was estimated at 1.6-2.2 for the Lima metropolitan area and 1.3-1.5 in the rest of Peru. We found a significant association between the timing of the school vacation period and changes in the age distribution of cases, while earlier pandemic onset was correlated with large population size. By contrast there was no association between pandemic dynamics and absolute humidity. Conclusions: Our results indicate substantial spatial variation in pandemic patterns across Peru, with two pandemic waves of varying timing and impact by age and region. Moreover, the Peru data suggest a hierarchical transmission pattern of pandemic influenza A/H1N1 driven by large population centers. The higher reproduction number of the first pandemic wave could be explained by high contact rates among school-age children, the age group most affected during this early wave.

Original languageEnglish (US)
Article numbere21287
JournalPLoS One
Volume6
Issue number6
DOIs
StatePublished - 2011

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Peru
Pandemics
pandemic
influenza
Human Influenza
vacations
Atmospheric humidity
Reproduction
Viruses
Age Distribution
Humidity
Health
winter
humidity
H1N1 Subtype Influenza A Virus
South America
monitoring
Virus Diseases
Orthomyxoviridae
Population Density

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Chowell, G., Viboud, C., Munayco, C. V., Gómez, J., Simonsen, L., Miller, M. A., ... Laguna-Torres, V. A. (2011). Spatial and temporal characteristics of the 2009 A/H1N1 influenza Pandemic in Peru. PLoS One, 6(6), [e21287]. https://doi.org/10.1371/journal.pone.0021287

Spatial and temporal characteristics of the 2009 A/H1N1 influenza Pandemic in Peru. / Chowell, Gerardo; Viboud, Cécile; Munayco, Cesar V.; Gómez, Jorge; Simonsen, Lone; Miller, Mark A.; Tamerius, James; Fiestas, Victor; Halsey, Eric S.; Laguna-Torres, Victor A.

In: PLoS One, Vol. 6, No. 6, e21287, 2011.

Research output: Contribution to journalArticle

Chowell, G, Viboud, C, Munayco, CV, Gómez, J, Simonsen, L, Miller, MA, Tamerius, J, Fiestas, V, Halsey, ES & Laguna-Torres, VA 2011, 'Spatial and temporal characteristics of the 2009 A/H1N1 influenza Pandemic in Peru', PLoS One, vol. 6, no. 6, e21287. https://doi.org/10.1371/journal.pone.0021287
Chowell G, Viboud C, Munayco CV, Gómez J, Simonsen L, Miller MA et al. Spatial and temporal characteristics of the 2009 A/H1N1 influenza Pandemic in Peru. PLoS One. 2011;6(6). e21287. https://doi.org/10.1371/journal.pone.0021287
Chowell, Gerardo ; Viboud, Cécile ; Munayco, Cesar V. ; Gómez, Jorge ; Simonsen, Lone ; Miller, Mark A. ; Tamerius, James ; Fiestas, Victor ; Halsey, Eric S. ; Laguna-Torres, Victor A. / Spatial and temporal characteristics of the 2009 A/H1N1 influenza Pandemic in Peru. In: PLoS One. 2011 ; Vol. 6, No. 6.
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abstract = "Background: Highly refined surveillance data on the 2009 A/H1N1 influenza pandemic are crucial to quantify the spatial and temporal characteristics of the pandemic. There is little information about the spatial-temporal dynamics of pandemic influenza in South America. Here we provide a quantitative description of the age-specific morbidity pandemic patterns across administrative areas of Peru. Methods: We used daily cases of influenza-like-illness, tests for A/H1N1 influenza virus infections, and laboratory-confirmed A/H1N1 influenza cases reported to the epidemiological surveillance system of Peru's Ministry of Health from May 1 to December 31, 2009. We analyzed the geographic spread of the pandemic waves and their association with the winter school vacation period, demographic factors, and absolute humidity. We also estimated the reproduction number and quantified the association between the winter school vacation period and the age distribution of cases. Results: The national pandemic curve revealed a bimodal winter pandemic wave, with the first peak limited to school age children in the Lima metropolitan area, and the second peak more geographically widespread. The reproduction number was estimated at 1.6-2.2 for the Lima metropolitan area and 1.3-1.5 in the rest of Peru. We found a significant association between the timing of the school vacation period and changes in the age distribution of cases, while earlier pandemic onset was correlated with large population size. By contrast there was no association between pandemic dynamics and absolute humidity. Conclusions: Our results indicate substantial spatial variation in pandemic patterns across Peru, with two pandemic waves of varying timing and impact by age and region. Moreover, the Peru data suggest a hierarchical transmission pattern of pandemic influenza A/H1N1 driven by large population centers. The higher reproduction number of the first pandemic wave could be explained by high contact rates among school-age children, the age group most affected during this early wave.",
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