Relative incidence and individual-level severity of seasonal influenza A H3N2 compared with 2009 pandemic H1N1.
Relative incidence and individual-level severity of seasonal influenza A H3N2 compared with 2009 pandemic H1N1.
复制标题
DOI：
10.1186/s12879-017-2432-7
复制
发表时间：
2017-05-11
影响因子：
3.7
通讯作者：
Cowling BJ
中科院分区：
文献类型：
--
作者：
Kwok KO;Riley S;Perera RAPM;Wei VWI;Wu P;Wei L;Chu DKW;Barr IG;Malik Peiris JS;Cowling BJ
甲型流感有两种亚型：季节性H3 N2（sH 3 N2，1968年出现）和大流行性H1N1（pH 1 N1，2009年出现）。虽然已经详细研究了pH 1 N1初始波的流行病学特征，但对其在后续波期间的感染动力学或其相对于sH 3 N2的严重程度知之甚少。即使在2009年之前，也很少有数据可用于估计感染一种流行流感毒株后相对于另一种流行流感毒株的严重后果风险。我们分析了2009年7月至2011年12月期间从香港收集的四份血清中的抗体，这一时期包括三次不同的流感病毒流行。我们使用这些检测数据估计感染发生率，然后使用人群范围内的临床数据估计每种感染的严重结局率。在第一次pH 1 N1流行中，儿童的累积感染率很高。从第一次到第二次流行，pH 1 N1感染的年龄分布向老年组变化，第二次流行的pH 1 N1的年龄分布与sH 3 N2的年龄分布更相似。我们没有发现任何血清学证据表明，个人感染了两波pH 1 N1。在整个研究期间，sH 3 N2的感染条件下的超额死亡率风险高于pH 1 N1，所有原因的年龄标准化风险比为2.6 [95%CI：1.8，3.7]，呼吸原因的年龄标准化风险比为1.5 [95%CI：1.0，2.1]。pH 1 N1临床发病率的总体增加和大流行后老年人中更高的严重率与感染向老年组的年龄转移一致。没有重复感染是很好的证据，表明免疫力减弱并没有引起第二波。尽管自1968年以来在人类中传播，但sH 3 N2每次感染比pH 1 N1菌株严重得多。基于感染的个人水平严重程度估计在评估新出现的毒株方面发挥着作用;更新季节性疫苗成分;以及优化疫苗接种计划。本文的在线版本（doi：10.1186/s12879-017-2432-7）包含补充材料，可供授权用户使用。
Two subtypes of influenza A currently circulate in humans: seasonal H3N2 (sH3N2, emerged in 1968) and pandemic H1N1 (pH1N1, emerged in 2009). While the epidemiological characteristics of the initial wave of pH1N1 have been studied in detail, less is known about its infection dynamics during subsequent waves or its severity relative to sH3N2. Even prior to 2009, few data was available to estimate the risk of severe outcomes following infection with one circulating influenza strain relative to another. We analyzed antibodies in quadruples of sera from individuals in Hong Kong collected between July 2009 and December 2011, a period that included three distinct influenza virus epidemics. We estimated infection incidence using these assay data and then estimated rates of severe outcomes per infection using population-wide clinical data. Cumulative incidence of infection was high among children in the first epidemic of pH1N1. There was a change towards the older age group in the age distribution of infections for pH1N1 from the first to the second epidemic, with the age distribution of the second epidemic of pH1N1 more similar to that of sH3N2. We found no serological evidence that individuals were infected in both waves of pH1N1. The risks of excess mortality conditional on infection were higher for sH3N2 than for pH1N1, with age-standardized risk ratios of 2.6 [95% CI: 1.8, 3.7] for all causes and 1.5 [95% CI: 1.0, 2.1] for respiratory causes throughout the study period. Overall increase in clinical incidence of pH1N1 and higher rates of severity in older adults in post pandemic waves were in line with an age-shift in infection towards the older age groups. The absence of repeated infection is good evidence that waning immunity did not cause the second wave. Despite circulating in humans since 1968, sH3N2 is substantially more severe per infection than the pH1N1 strain. Infection-based estimates of individual-level severity have a role in assessing emerging strains; updating seasonal vaccine components; and optimizing of vaccination programs. The online version of this article (doi:10.1186/s12879-017-2432-7) contains supplementary material, which is available to authorized users.