Department of Public Health and Center for Infectious Disease Epidemiology Research, China Medical University, Taichung, Taiwan.
Influenza Other Respir Viruses. 2010 Jul;4(4):187-97. doi: 10.1111/j.1750-2659.2010.00147.x.
Countries in the southern hemisphere experienced sizable epidemics of pandemic influenza H1N1 in their winter season during May-August, 2009.
We make use of the Richards model to fit the publicly available epidemic data (confirmed cases, hospitalizations, and deaths) of six southern hemisphere countries (Argentina, Brazil, Chile, Australia, New Zealand, and South Africa) to draw useful conclusions, in terms of its reproduction numbers and outbreak turning points, regarding the new pH1N1 virus in a typical winter influenza season.
The estimates for the reproduction numbers of these six countries range from a high of 1.53 (95% CI: 1.22, 1.84) for confirmed case data of Brazil to a low of 1.16 (1.09, 1.22) for pH1N1 hospitalizations in Australia. For each country, model fits using confirmed cases, hospitalizations, or deaths data always yield similar estimates for the reproduction number. Moreover, the turning points for these closely related outbreak indicators always follow the correct chronological order, i.e., case-hospitalization-death, whenever two or more of these three indicators are available.
The results suggest that the winter pH1N1 outbreaks in the southern hemisphere were similar to the earlier spring and later winter outbreaks in North America in its severity and transmissibility, as indicated by the reproduction numbers. Therefore, the current strain has not become more severe or transmissible while circulating around the globe in 2009 as some experts had cautioned. The results will be useful for global preparedness planning of possible tertiary waves of pH1N1 infections in the fall/winter of 2010.
南半球国家在 2009 年 5 月至 8 月的冬季经历了大流行流感 H1N1 的疫情。
我们利用 Richards 模型拟合六个南半球国家（阿根廷、巴西、智利、澳大利亚、新西兰和南非）公开的流行病情数据（确诊病例、住院和死亡），以得出有关新 pH1N1 病毒在典型冬季流感季节中的繁殖数量和爆发转折点的有用结论。
这六个国家的繁殖数量估计值从巴西确诊病例数据的 1.53（95%置信区间：1.22，1.84）到澳大利亚 pH1N1 住院数据的 1.16（1.09，1.22）不等。对于每个国家，使用确诊病例、住院或死亡数据进行模型拟合总是会得出繁殖数量的相似估计值。此外，这些密切相关的爆发指标的转折点总是遵循正确的时间顺序，即病例-住院-死亡，只要这三个指标中的两个或更多个可用。
结果表明，南半球的冬季 pH1N1 疫情在严重程度和传染性方面与北美早期的春季和后期的冬季疫情相似，如繁殖数量所示。因此，与一些专家警告的不同，2009 年在全球传播期间，该病毒株并没有变得更严重或更具传染性。这些结果将有助于为 2010 年秋季/冬季可能出现的 pH1N1 感染的第三次浪潮做好全球准备计划。
