Kile James C, Ren Ruiqi, Liu Liqi, Greene Carolyn M, Roguski Katherine, Iuliano A Danielle, Jang Yunho, Jones Joyce, Thor Sharmi, Song Ying, Zhou Suizan, Trock Susan C, Dugan Vivien, Wentworth David E, Levine Min Z, Uyeki Timothy M, Katz Jacqueline M, Jernigan Daniel B, Olsen Sonja J, Fry Alicia M, Azziz-Baumgartner Eduardo, Davis C Todd
MMWR Morb Mortal Wkly Rep. 2017 Sep 8;66(35):928-932. doi: 10.15585/mmwr.mm6635a2.
Among all influenza viruses assessed using CDC's Influenza Risk Assessment Tool (IRAT), the Asian lineage avian influenza A(H7N9) virus (Asian H7N9), first reported in China in March 2013,* is ranked as the influenza virus with the highest potential pandemic risk (1). During October 1, 2016-August 7, 2017, the National Health and Family Planning Commission of China; CDC, Taiwan; the Hong Kong Centre for Health Protection; and the Macao CDC reported 759 human infections with Asian H7N9 viruses, including 281 deaths, to the World Health Organization (WHO), making this the largest of the five epidemics of Asian H7N9 infections that have occurred since 2013 (Figure 1). This report summarizes new viral and epidemiologic features identified during the fifth epidemic of Asian H7N9 in China and summarizes ongoing measures to enhance pandemic preparedness. Infections in humans and poultry were reported from most areas of China, including provinces bordering other countries, indicating extensive, ongoing geographic spread. The risk to the general public is very low and most human infections were, and continue to be, associated with poultry exposure, especially at live bird markets in mainland China. Throughout the first four epidemics of Asian H7N9 infections, only low pathogenic avian influenza (LPAI) viruses were detected among human, poultry, and environmental specimens and samples. During the fifth epidemic, mutations were detected among some Asian H7N9 viruses, identifying the emergence of high pathogenic avian influenza (HPAI) viruses as well as viruses with reduced susceptibility to influenza antiviral medications recommended for treatment. Furthermore, the fifth-epidemic viruses diverged genetically into two separate lineages (Pearl River Delta lineage and Yangtze River Delta lineage), with Yangtze River Delta lineage viruses emerging as antigenically different compared with those from earlier epidemics. Because of its pandemic potential, candidate vaccine viruses (CVV) were produced in 2013 that have been used to make vaccines against Asian H7N9 viruses circulating at that time. CDC is working with partners to enhance surveillance for Asian H7N9 viruses in humans and poultry, to improve laboratory capability to detect and characterize H7N9 viruses, and to develop, test and distribute new CVV that could be used for vaccine production if a vaccine is needed.
在中国疾病预防控制中心（CDC）的流感风险评估工具（IRAT）评估的所有流感病毒中，2013年3月首次在中国报告的亚洲系甲型H7N9禽流感病毒（亚洲H7N9）*被列为大流行风险最高的流感病毒（1）。在2016年10月1日至2017年8月7日期间，中国国家卫生和计划生育委员会、台湾疾病预防控制中心、香港卫生防护中心以及澳门疾病预防控制中心向世界卫生组织（WHO）报告了759例人类感染亚洲H7N9病毒的病例，其中包括281例死亡病例，这是自2013年以来发生的五起亚洲H7N9感染疫情中规模最大的一次（图1）。本报告总结了在中国发生的亚洲H7N9第五波疫情期间发现的新病毒特征和流行病学特征，并总结了为加强大流行防范而正在采取的措施。在中国大部分地区，包括与其他国家接壤的省份，均报告了人类和家禽感染情况，表明该病毒正在广泛且持续地进行地理传播。对普通公众的风险非常低，而且大多数人类感染过去是、现在仍然是与接触家禽有关，尤其是在中国内地的活禽市场。在亚洲H7N9感染的前四波疫情中，在人类、家禽和环境标本及样本中仅检测到低致病性禽流感（LPAI）病毒。在第五波疫情期间，在一些亚洲H7N9病毒中检测到了变异，确认出现了高致病性禽流感（HPAI）病毒以及对推荐用于治疗的流感抗病毒药物敏感性降低的病毒。此外，第五波疫情病毒在基因上分化为两个独立的谱系（珠江三角洲谱系和长江三角洲谱系），与早期疫情中的病毒相比，长江三角洲谱系病毒在抗原性上有所不同。由于其大流行潜力，2013年生产了候选疫苗病毒（CVV），这些病毒已被用于制备针对当时流行的亚洲H7N9病毒的疫苗。美国疾病预防控制中心正在与合作伙伴合作，加强对人类和家禽中亚洲H7N9病毒的监测，提高检测和鉴定H7N9病毒的实验室能力，并研发、测试和分发新的候选疫苗病毒，如果需要，可以用于生产疫苗。
