Meeyai Aronrag, Cooper Ben, Coker Richard, Pan-Ngum Wirichada, Akarasewi Pasakorn, Iamsirithaworn Sopon
Department of Epidemiology, Faculty of Public Health, Mahidol University; Communicable Diseases Policy Research Group, London School of Hygiene & Tropical Medicine, Bangkok, Thailand.
Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
WHO South East Asia J Public Health. 2012 Jan-Mar;1(1):59-68. doi: 10.4103/2224-3151.206915.
Developing a quantitative understanding of pandemic influenza dynamics in South-East Asia is important for informing future pandemic planning. Hence, transmission dynamics of influenza A/H1N1 were determined across space and time in Thailand.
Dates of symptom onset were obtained for all daily laboratory-confirmed cases of influenza A/H1N1pdm in Thailand from 3 May 2009 to 26 December 2010 for four different geographic regions (Central, North, North-East, and South). These data were analysed using a probabilistic epidemic reconstruction, and estimates of the effective reproduction number, R(t), were derived by region and over time.
Estimated R(t) values for the first wave peaked at 1.54 (95% CI: 1.42-1.71) in the Central region and 1.64 (95% CI: 1.38-1.92) in the North, whilst the corresponding values in the North-East and the South were 1.30 (95% CI: 1.17-1.46) and 1.39 (95% CI: 1.32-1.45) respectively. As the R(t) in the Central region fell below one, the value of R(t) in the rest of Thailand increased above one. R(t) was above one for 30 days continuously through the first wave in all regions of Thailand. During the second wave R(t) was only marginally above one in all regions except the South.
In Thailand, the value of R(t) varied by region in the two pandemic waves. Higher R(t) estimates were found in Central and Northern regions in the first wave. Knowledge of regional variation in transmission potential is needed for predicting the course of future pandemics and for analysing the potential impact of control measures.
对东南亚大流行性流感动态进行定量理解，对于为未来大流行规划提供信息很重要。因此，在泰国确定了甲型H1N1流感的传播动态在空间和时间上的情况。
获取了2009年5月3日至2010年12月26日泰国四个不同地理区域（中部、北部、东北部和南部）所有每日实验室确诊的甲型H1N1pdm流感病例的症状出现日期。使用概率性疫情重建方法对这些数据进行分析，并按区域和随时间推导出有效再生数R(t)的估计值。
第一波的估计R(t)值在中部地区峰值为1.54（95%置信区间：1.42 - 1.71），在北部为1.64（95%置信区间：1.38 - 1.92），而东北部和南部的相应值分别为1.30（95%置信区间：1.17 - 1.46）和1.39（95%置信区间：1.32 - 1.45）。当中部地区的R(t)降至1以下时，泰国其他地区的R(t)值升至1以上。在泰国所有地区，第一波期间R(t)连续30天高于1。在第二波期间，除南部外，所有地区的R(t)仅略高于1。
在泰国，两次大流行波中R(t)值因地区而异。第一波中中部和北部地区的R(t)估计值较高。预测未来大流行的进程以及分析控制措施的潜在影响需要了解传播潜力的区域差异。
