Yang Lin, Chan Kwok Hung, Suen Lorna K P, Chan King Pan, Wang Xiling, Cao Peihua, He Daihai, Peiris J S Malik, Wong Chit Ming
School of Nursing, The Hong Kong Polytechnic University, Hong Kong.
Department of Microbiology, The University of Hong Kong, Hong Kong.
PLoS One. 2015 Apr 30;10(4):e0125447. doi: 10.1371/journal.pone.0125447. eCollection 2015.
The 2009 H1N1 influenza pandemic caused offseason peaks in temperate regions but coincided with the summer epidemic of seasonal influenza and other common respiratory viruses in subtropical Hong Kong. This study was aimed to investigate the impact of the pandemic on age-specific epidemic curves of other respiratory viruses.
Weekly laboratory-confirmed cases of influenza A (subtypes seasonal A(H1N1), A(H3N2), pandemic virus A(H1N1)pdm09), influenza B, respiratory syncytial virus (RSV), adenovirus and parainfluenza were obtained from 2004 to 2013. Age-specific epidemic curves of viruses other than A(H1N1)pdm09 were compared between the pre-pandemic (May 2004-April 2009), pandemic (May 2009-April 2010) and post-pandemic periods (May 2010-April 2013).
There were two peaks of A(H1N1)pdm09 in Hong Kong, the first in September 2009 and the second in February 2011. The infection rate was found highest in young children in both waves, but markedly fewer cases in school children were recorded in the second wave than in the first wave. Positive proportions of viruses other than A(H1N1)pdm09 markedly decreased in all age groups during the first pandemic wave. After the first wave of the pandemic, the positive proportion of A(H3N2) increased, but those of B and RSV remained slightly lower than their pre-pandemic proportions. Changes in seasonal pattern and epidemic peak time were also observed, but inconsistent across virus-age groups.
Our findings provide some evidence that age distribution, seasonal pattern and peak time of other respiratory viruses have changed since the pandemic. These changes could be the result of immune interference and changing health seeking behavior, but the mechanism behind still needs further investigations.
2009年甲型H1N1流感大流行在温带地区造成了非季节性高峰，但在亚热带的香港，它与季节性流感及其他常见呼吸道病毒的夏季流行同时发生。本研究旨在调查此次大流行对其他呼吸道病毒特定年龄流行曲线的影响。
获取了2004年至2013年每周经实验室确诊的甲型流感（季节性甲型H1N1、甲型H3N2、大流行病毒甲型H1N1pdm09亚型）、乙型流感、呼吸道合胞病毒（RSV）、腺病毒和副流感的病例。比较了大流行前（2004年5月至2009年4月）、大流行期间（2009年5月至2010年4月）和大流行后时期（2010年5月至2013年4月）除甲型H1N1pdm09之外的其他病毒的特定年龄流行曲线。
香港出现了两次甲型H1N1pdm09高峰，第一次在2009年9月，第二次在2011年2月。在两波疫情中，幼儿的感染率最高，但第二波记录的学龄儿童病例明显少于第一波。在第一波大流行期间，所有年龄组中除甲型H1N1pdm09之外的其他病毒的阳性比例显著下降。在大流行的第一波之后，甲型H3N2的阳性比例增加，但乙型流感和呼吸道合胞病毒的阳性比例仍略低于大流行前的比例。还观察到了季节性模式和流行高峰时间的变化，但在病毒-年龄组之间并不一致。
我们的研究结果提供了一些证据，表明自此次大流行以来，其他呼吸道病毒的年龄分布、季节性模式和高峰时间发生了变化。这些变化可能是免疫干扰和就医行为改变的结果，但其背后的机制仍需进一步研究。
