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Ann Intern Med. Deaths Associated with Avian Influenza A(H7N9) Virus in China

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  • Ann Intern Med. Deaths Associated with Avian Influenza A(H7N9) Virus in China

    [Source: Annals of Internal Medicine, full text: (LINK). Abstract, edited.]
    Letters | 4 June 2013

    Deaths Associated with Avian Influenza A(H7N9) Virus in China


    Yuehua Ke, PhD, MD; Yufei Wang, PhD, MD; Wenyi Zhang, MD; Liuyu Huang, PhD; and Zeliang Chen, PhD, MD

    Ann Intern Med. Published online 4 June 2013



    A novel avian influenza A(H7N9) virus has recently emerged in China. The first human cases were characterized by rapidly progressive pneumonia, respiratory failure, the acute respiratory distress syndrome, and fatal outcome. As of 30 April 2013, 126 cases of human infection resulting in 24 deaths have been reported in 10 Chinese provinces.


    To describe the characteristics of the 24 fatal cases.


    We obtained information from the National Surveillance System and the National Health and Family Planning Commission. Cases were confirmed with reverse transcription polymerase chain reaction assays of upper respiratory secretions using methods and reagents developed by the Chinese Center for Disease Control and Prevention. Close contacts were defined as people who came within 1 meter of an infected patient or had direct contact with respiratory secretions or fecal material from the day before illness onset to hospital isolation. Close contacts were monitored daily by telephone or in person, and throat swabs were collected from persons with fever or respiratory symptoms and tested at the Chinese Center for Disease Control and Prevention. We used SPSS 17.0 (SPSS, Chicago, Illinois) to calculate descriptive statistics.


    The 24 deaths occurred in 4 provinces in eastern China: Shanghai (n = 13), Zhejiang (n = 6), Jiangsu (n = 4), and Anhui (n = 1). For the rest of our analyses, we excluded 2 deaths confirmed as H7N9 illness because other information was not available. Among the remaining deaths, 16 were male and aged 60 years or older. The median age of the 22 deaths was 68 years (interquartile range [IQR], 51.0 to 78.5 years). At the time that the diagnosis was confirmed, 8 patients had died, 2 were critically ill, 8 were severely ill, and 4 were stable. We calculated the number of days from symptom onset to first medical care visit (median, 2 days [IQR, 0 to 4.0 days]), to hospitalization (median, 5 days [IQR, 2.75 to 6.25 days]), to confirmation of the diagnosis (median, 9.5 days [IQR, 6.25 to 14.5 days]), and to death (median, 13 days [IQR, 8.50 to 16.0 days]). We also calculated the number of days from first medical care visit to death (median, 11 days [IQR, 4.5 to 16.0 days]), from hospitalization to death (median, 10 days [IQR, 1.75 to 14.5 days]), and from confirmation of the diagnosis to death (median, 5 days [IQR, 1.0 to 9.5 days]). In addition, 14 patients with available information had 330 close contacts. None of the contacts was infected with H7N9 virus during 7 days of monitoring, which is 1 incubation period.


    Infection of humans by novel influenza A viruses that are distinct from circulating viruses and produce severe disease can lead to sporadic human infections or influenza pandemics. Therefore, the recent discovery of the H7N9 virus is of great public health interest. Because most of the deaths we report occurred in patients aged 60 or older, it is reasonable to consider this demographic at high risk while we learn more about age distribution. In addition, the illness progresses rapidly after symptoms first appear; therefore, in suspected cases clinicians should plan to test for the diagnosis and treat early. The current case-fatality rate for H7N9 infection is 19%, which is much higher than that for seasonal influenza and pandemic H1N1 influenza (0.1% to 1%), but lower than that for avian influenza H5N1 (40% to 60%). However, the case-fatality rate for H7N9 infection should decrease as we learn more about the disease because cases with more severe illnesses are identified earlier in the study of most new diseases. Moreover, no H7N9 virus infections were found among close human contacts of the patients who died, which may allow us to worry a little less about human-to-human transmission of this virus.

    Collectively, our data suggest that H7N9 virus infection has a relatively high case-fatality rate and progresses rapidly from symptom onset to severe illness and death. Therefore, clinicians should start antiviral treatment when infection with H7N9 virus is first suspected.

    From Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing, China.

    Editor's Note: This is an online-first article. This version will have minor typographical differences from the final, printed version.

    Note: Drs. Ke, Wang, Zhang, and Huang contributed equally to this work.

    Grant Support: By the National Key Program for Infectious Diseases of China (2013ZX10004-203, 2013ZX10004-217-002, 2013ZX10004805-006).

    Potential Conflicts of Interest: None disclosed.

    This article was published at on 4 June 2013.

  • #2
    Re: Ann Intern Med. Deaths Associated with Avian Influenza A(H7N9) Virus in China

    Ann Intern Med. 2013 Aug 20;159(4):308. doi: 10.7326/0003-4819-159-4-201308200-00021.
    Correction: Deaths Associated With Avian Influenza A(H7N9) Virus in China.
    [No authors listed]

    [PubMed - as supplied by publisher]