Transmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.

While in Northern hemisphere countries, the pandemic H1N1 virus (H1N1pdm) was introduced outside of the typical influenza season, Southern hemisphere countries experienced a single wave of transmission during their 2009 winter season. This provides a unique opportunity to compare the spread of a sin...

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Autores principales:	Lulla Opatowski, Christophe Fraser, Jamie Griffin, Eric de Silva, Maria D Van Kerkhove, Emily J Lyons, Simon Cauchemez, Neil M Ferguson
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2011
Materias:	Immunologic diseases. Allergy RC581-607 Biology (General) QH301-705.5
Acceso en línea:	https://doaj.org/article/23f9d6aaa46b457d96e8dbcffe4be415
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spelling	oai:doaj.org-article:23f9d6aaa46b457d96e8dbcffe4be4152021-11-18T06:03:01ZTransmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.1553-73661553-737410.1371/journal.ppat.1002225https://doaj.org/article/23f9d6aaa46b457d96e8dbcffe4be4152011-09-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/21909272/?tool=EBIhttps://doaj.org/toc/1553-7366https://doaj.org/toc/1553-7374While in Northern hemisphere countries, the pandemic H1N1 virus (H1N1pdm) was introduced outside of the typical influenza season, Southern hemisphere countries experienced a single wave of transmission during their 2009 winter season. This provides a unique opportunity to compare the spread of a single virus in different countries and study the factors influencing its transmission. Here, we estimate and compare transmission characteristics of H1N1pdm for eight Southern hemisphere countries/states: Argentina, Australia, Bolivia, Brazil, Chile, New Zealand, South Africa and Victoria (Australia). Weekly incidence of cases and age-distribution of cumulative cases were extracted from public reports of countries' surveillance systems. Estimates of the reproduction numbers, R(0), empirically derived from the country-epidemics' early exponential phase, were positively associated with the proportion of children in the populations (p = 0.004). To explore the role of demography in explaining differences in transmission intensity, we then fitted a dynamic age-structured model of influenza transmission to available incidence data for each country independently, and for all the countries simultaneously. Posterior median estimates of R₀ ranged 1.2-1.8 for the country-specific fits, and 1.29-1.47 for the global fits. Corresponding estimates for overall attack-rate were in the range 20-50%. All model fits indicated a significant decrease in susceptibility to infection with age. These results confirm the transmissibility of the 2009 H1N1 pandemic virus was relatively low compared with past pandemics. The pattern of age-dependent susceptibility found confirms that older populations had substantial--though partial--pre-existing immunity, presumably due to exposure to heterologous influenza strains. Our analysis indicates that between-country-differences in transmission were at least partly due to differences in population demography.Lulla OpatowskiChristophe FraserJamie GriffinEric de SilvaMaria D Van KerkhoveEmily J LyonsSimon CauchemezNeil M FergusonPublic Library of Science (PLoS)articleImmunologic diseases. AllergyRC581-607Biology (General)QH301-705.5ENPLoS Pathogens, Vol 7, Iss 9, p e1002225 (2011)
institution	DOAJ
collection	DOAJ
language	EN
topic	Immunologic diseases. Allergy RC581-607 Biology (General) QH301-705.5
spellingShingle	Immunologic diseases. Allergy RC581-607 Biology (General) QH301-705.5 Lulla Opatowski Christophe Fraser Jamie Griffin Eric de Silva Maria D Van Kerkhove Emily J Lyons Simon Cauchemez Neil M Ferguson Transmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.
description	While in Northern hemisphere countries, the pandemic H1N1 virus (H1N1pdm) was introduced outside of the typical influenza season, Southern hemisphere countries experienced a single wave of transmission during their 2009 winter season. This provides a unique opportunity to compare the spread of a single virus in different countries and study the factors influencing its transmission. Here, we estimate and compare transmission characteristics of H1N1pdm for eight Southern hemisphere countries/states: Argentina, Australia, Bolivia, Brazil, Chile, New Zealand, South Africa and Victoria (Australia). Weekly incidence of cases and age-distribution of cumulative cases were extracted from public reports of countries' surveillance systems. Estimates of the reproduction numbers, R(0), empirically derived from the country-epidemics' early exponential phase, were positively associated with the proportion of children in the populations (p = 0.004). To explore the role of demography in explaining differences in transmission intensity, we then fitted a dynamic age-structured model of influenza transmission to available incidence data for each country independently, and for all the countries simultaneously. Posterior median estimates of R₀ ranged 1.2-1.8 for the country-specific fits, and 1.29-1.47 for the global fits. Corresponding estimates for overall attack-rate were in the range 20-50%. All model fits indicated a significant decrease in susceptibility to infection with age. These results confirm the transmissibility of the 2009 H1N1 pandemic virus was relatively low compared with past pandemics. The pattern of age-dependent susceptibility found confirms that older populations had substantial--though partial--pre-existing immunity, presumably due to exposure to heterologous influenza strains. Our analysis indicates that between-country-differences in transmission were at least partly due to differences in population demography.
format	article
author	Lulla Opatowski Christophe Fraser Jamie Griffin Eric de Silva Maria D Van Kerkhove Emily J Lyons Simon Cauchemez Neil M Ferguson
author_facet	Lulla Opatowski Christophe Fraser Jamie Griffin Eric de Silva Maria D Van Kerkhove Emily J Lyons Simon Cauchemez Neil M Ferguson
author_sort	Lulla Opatowski
title	Transmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.
title_short	Transmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.
title_full	Transmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.
title_fullStr	Transmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.
title_full_unstemmed	Transmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.
title_sort	transmission characteristics of the 2009 h1n1 influenza pandemic: comparison of 8 southern hemisphere countries.
publisher	Public Library of Science (PLoS)
publishDate	2011
url	https://doaj.org/article/23f9d6aaa46b457d96e8dbcffe4be415
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Transmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.

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