Boëlle P Y, Bernillon P, Desenclos J C
INSERM, Institut National de la Santé et de la Recherche Medicale (National Institute of Health and Medical Research), U707, Paris, France.
Euro Surveill. 2009 May 14;14(19):19205. doi: 10.2807/ese.14.19.19205-en.
As of 12 May 2009, 5,251 cases of the new influenza A(H1N1) have been officially reported to the World Health Organization (WHO) from 30 countries, with most of the identified cases exported from Mexico where a local epidemic has been going on for the last two months. Sustained human-to-human transmission is necessary to trigger influenza pandemic and estimating the reproduction ratio (average number of secondary cases per primary case) is necessary for forecasting the spread of infection. We use two methods to estimate the reproduction ratio from the epidemic curve in Mexico using three plausible generation intervals (the time between primary and secondary case infection). As expected, the reproduction ratio estimates were highly sensitive to assumptions regarding the generation interval, which remains to be estimated for the current epidemic. Here, we suggest that the reproduction ratio was less than 2.2 - 3.1 in Mexico, depending on the generation interval. Monitoring and updating the reproduction ratio estimate as the epidemic spreads outside Mexico into different settings should remain a priority for assessing the situation and helping to plan public health interventions.
截至2009年5月12日，已有30个国家向世界卫生组织（WHO）正式报告了5251例新型甲型H1N1流感病例，其中大多数确诊病例来自墨西哥，在过去两个月里墨西哥一直在发生局部疫情。持续的人际传播是引发流感大流行的必要条件，而估计繁殖率（每例原发病例继发病例的平均数量）对于预测感染传播至关重要。我们使用两种方法，利用三个合理的代间隔（原发病例与继发病例感染之间的时间），根据墨西哥的疫情曲线来估计繁殖率。正如预期的那样，繁殖率估计对代间隔的假设高度敏感，而目前疫情的代间隔仍有待估计。在此，我们认为，根据代间隔的不同，墨西哥的繁殖率低于2.2 - 3.1。随着疫情从墨西哥蔓延到不同地区，监测并更新繁殖率估计值应始终是评估形势和帮助规划公共卫生干预措施的优先事项。
