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We investigated potential sources of infection for 6 confirmed influenza A (H5N1) patients who resided in urban areas of People's Republic of China. None had known exposure to sick poultry or poultry that died from illness, but all had visited wet poultry markets before illness. [ABSTRACT FROM AUTHOR]

Problem In 2003, China's handling of the early stages of the epidemic of severe acute respiratory syndrome (SARS) was heavily criticized and generally considered to be suboptimal. Approach Following the SARS outbreak, China made huge investments to improve surveillance, emergency preparedness and response capacity and strengthen public health institutions. In 2013, the return on these investments was evaluated by investigating China's early response to the emergence of avian influenza A(H7N9) virus in humans. Local setting Clusters of human infection with a novel influenza virus were detected in China--by national surveillance of pneumonia of unknown etiology--on 26 February 2013. Relevant changes On 31 March 2013, China notified the World Health Organization (WHO) of the first recorded human infections with A(H7N9) virus. Poultry markets--which were rapidly identified as a major source of transmission of A(H7N9) to humans--were closed down in the affected areas. Surveillance in humans and poultry was heightened and technical guidelines were quickly updated and disseminated. The health authorities collaborated with WHO in risk assessments and risk communication. New cases were reported promptly and publicly. Lessons learnt The relevant infrastructures, surveillance systems and response capacity need to be strengthened in preparation for future emergencies caused by emerging or existing disease threats. Results of risk assessments and other data should be released promptly and publicly and such release should not jeopardize future publication of the data in scientific journals. Coordination between public health and veterinary services would be stronger during an emergency if these services had already undertaken joint preparedness planning. [ABSTRACT FROM AUTHOR]

Background: H7N9 human cases were first detected in mainland China in March 2013. Circulation of this virus has continued each year shifting to typical winter months. We compared the clinical and epidemiologic characteristics for the first three waves of virus circulation. Methods: The first wave was defined as reported cases with onset dates between March 31-September 30, 2013, the second wave was defined as October 1, 2013-September 30, 2014 and the third wave was defined as October 1, 2014-September 30, 2015. We used simple descriptive statistics to compare characteristics of the three distinct waves of virus circulation. Results: In mainland China, 134 cases, 306 cases and 219 cases were detected and reported in first three waves, respectively. The median age of cases was statistically significantly older in the first wave (61 years vs. 56 years, 56 years, p < 0.001) compared to the following two waves. Most reported cases were among men in all three waves. There was no statistically significant difference between case fatality proportions (33, 42 and 45%, respectively, p = 0.08). There were no significant statistical differences for time from illness onset to first seeking healthcare, hospitalization, lab confirmation, initiation antiviral treatment and death between the three waves. A similar percentage of cases in all waves reported exposure to poultry or live poultry markets (87%, 88%, 90%, respectively). There was no statistically significant difference in the occurrence of severe disease between the each of the first three waves of virus circulation. Twenty-one clusters were reported during these three waves (4, 11 and 6 clusters, respectively), of which, 14 were considered to be possible human-to-human transmission. Conclusion: Though our case investigation for the first three waves found few differences between the epidemiologic and clinical characteristics, there is continued international concern about the pandemic potential of this virus. Since the virus continues to circulate, causes more severe disease, has the ability to mutate and become transmissible from human-to-human, and there is limited natural protection from infection in communities, it is critical that surveillance systems in China and elsewhere are alert to the influenza H7N9 virus. [ABSTRACT FROM AUTHOR]

Objective To estimate influenza-associated mortality in urban China. Methods Influenza-associated excess mortality for the period 2003-2008 was estimated in three cities in temperate northern China and five cities in the subtropical south of the country. The estimates were derived from models based on negative binomial regressions, vital statistics and the results of weekly influenza virus surveillance. Findings Annual influenza-associated excess mortality, for all causes, was 18.0 (range: 10.9-32.7) deaths per 100 000 population in the northern cities and 11.3 (range: 7.3-17.8) deaths per 100 000 in the southern cities. Excess mortality for respiratory and circulatory disease was 12.4 (range: 7.4-22.2) and 8.8 (range: 5.5-13.6) deaths per 100 000 people in the northern and southern cities, respectively. Most (86%) deaths occurred among people aged ≥ 65 years. Influenza-associated excess mortality was higher in B-virus-dominant seasons than in seasons when A(H3N2) or A(H1N1) predominated, and more than half of all influenza-associated mortality was associated with influenza B virus. Conclusion Between 2003 and 2008, seasonal influenza, particularly that caused by the influenza B virus, was associated with substantial mortality in three cities in the temperate north of China and five cities in the subtropical south of the country. [ABSTRACT FROM AUTHOR]

Background. Glucocorticoids increase the risk of developing critical disease from viral infections. However, primary care practitioners in China use them as antipyretics, potentially exposing hundreds of millions to this risk. Methods. We enrolled all patients with confirmed pandemic influenza A (pH1N1) virus infection aged ⩾3 years with available medical records at 4 Shenyang City hospitals from 20 October to 30 November 2009. A critical patient was any confirmed, hospitalized pH1N1 patient who developed ⩾1 of the following: death, respiratory failure, septic shock, failure or insufficiency of ⩾2 nonpulmonary organs, mechanical ventilation, or ICU admission. In a retrospective cohort study, we evaluated the risk of developing critical illness in relation to early (⩽72 hours of influenza-like illness [ILI] onset) glucocorticoids treatment. Results. Of the 83 hospitalized case-patients, 46% developed critical illness, 17% died, and 37% recovered and were discharged. Critically ill and other patients did not differ by underlying conditions and severity, median temperature at first clinic visit, and other measured risk factors. Of 17 patients who received early glucocorticoid treatment, 71% subsequently developed critical disease compared with 39% of 66 patients who received late (>72 hours) or no glucocorticoid treatment (RRM-H 5 1.8, 95% CI 5 1.2-2.8, after adjusting for 2 summary variables; ie, presence of underlying diseases and presence of underlying risk factors). Proportional hazards modeling showed that use of glucocorticoids tripled the hazard of developing critical disease (hazard ratio [HR] 5 2.9, 95% CI 5 1.3-6.2, after adjusting for the same summary variables). Conclusions. Early use of parenteral glucocorticoids therapy for fever reduction and pneumonia prevention increases the risk for critical disease or death from pH1N1 infection. We recommend that guidelines on glucocorticoid use be established and enforced. [ABSTRACT FROM AUTHOR]

Background The next influenza pandemic will create a surge in demand for health resources in China, with its current population of >1·3 billion persons and under-developed medical care and public health system. However, few pandemic impact data are available for China. Objectives We estimated the effects of a future influenza pandemic in China by examining pandemic scenarios of varying severity and described the time distribution of cases during a first wave. Methods  We used a Monte-Carlo simulation model and death rates, hospitalizations and outpatient visits for 1918- and 1968-like pandemic scenarios and data from the literature or experts’ opinion to estimate four health outcomes: deaths, hospitalizations, outpatient medical visits and clinical illness for which medical care was not sought. For each of the two scenarios we estimated outcomes by week using a normal distribution. Results We estimated that a 1968 scenario in China would result in 460 000–700 000 deaths, 1·94–2·27 million hospitalizations, 111–117 million outpatient visits and 192–197 million illnesses for which medical care was not sought. Fifty-two percent of hospitalizations occurred during the two-peak weeks of the first wave. We estimated that patients at high-risk of influenza complications (10–17% of the population) would account for 61–75% of all deaths. For a 1918 scenario, we estimated that 4·95–6·95 million deaths, 20·8–22·7 million hospitalizations and 101–108 million outpatient visits could occur. Conclusion Even a 1968 pandemic scenario will pose substantial challenges for the medical and public health system in China, and planning to manage these challenges is essential. [ABSTRACT FROM AUTHOR]

Background. In China, 30 human cases of avian influenza A (H5N1) virus infection were identified through July 2008. We conducted a retrospective case-control study to identify risk factors for influenza H5N1 disease in China. Methods. A questionnaire about potential influenza H5N1 exposures was administered to 28 patients with influenza H5N1 and to 134 randomly selected control subjects matched by age, sex, and location or to proxies. Conditional logistic regression analyses were performed. Results. Before their illness, patients living in urban areas had visited wet poultry markets, and patients living in rural areas had exposure to sick or dead backyard poultry. In multivariable analyses, independent risk factors for influenza H5N1 were direct contact with sick or dead poultry (odds ratio [OR], 506.6 [95% confidence interval {CI}, 15.7-16319.6]; P < .001), indirect exposure to sick or dead poultry (OR, 56.9 [95% CI, 4.3-745.6]; P = .002), and visiting a wet poultry market (OR, 15.4 [95% CI, 3.0-80.2]; P = .001). Conclusions. To prevent human influenza H5N1 in China, the level of education about avoiding direct or close exposures to sick or dead poultry should be increased, and interventions to prevent the spread of influenza H5N1 at live poultry markets should be implemented. [ABSTRACT FROM AUTHOR]