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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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2011-09-01
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| Series: | PLoS Pathogens |
| Online Access: | https://journals.plos.org/plospathogens/article/file?id=10.1371/journal.ppat.1002225&type=printable |
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| 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 |
| collection | DOAJ |
| 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 |
| id | doaj-art-23f9d6aaa46b457d96e8dbcffe4be415 |
| institution | DOAJ |
| issn | 1553-7366 1553-7374 |
| language | English |
| publishDate | 2011-09-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Pathogens |
| spelling | doaj-art-23f9d6aaa46b457d96e8dbcffe4be4152025-08-20T03:09:47ZengPublic Library of Science (PLoS)PLoS Pathogens1553-73661553-73742011-09-0179e100222510.1371/journal.ppat.1002225Transmission characteristics of the 2009 H1N1 influenza pandemic: comparison of 8 Southern hemisphere countries.Lulla OpatowskiChristophe FraserJamie GriffinEric de SilvaMaria D Van KerkhoveEmily J LyonsSimon CauchemezNeil M FergusonWhile 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.https://journals.plos.org/plospathogens/article/file?id=10.1371/journal.ppat.1002225&type=printable |
| spellingShingle | 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. PLoS Pathogens |
| title | 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_short | 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 |
| url | https://journals.plos.org/plospathogens/article/file?id=10.1371/journal.ppat.1002225&type=printable |
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