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Update H7N9 AI outbreak in China, ECDC, April 11, 2013

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China is opening up and learnt from the past it seams. They started to share information, but only in relation to the human cases. Not a word about the source of the outbreaks. Not a word over where the infected farms are. Pigeons are very unlikely to spread the virus through markets. If you have to run the biggest town of China, providing the people with eggs and poultry meat, you need extremely large farms, close to the customers. Well-protected, because of the risks that the animals are going to be infected. Think what the financial consequences would be if these farms should have to e closed.

One of the things that is important when it comes to human infections is the Case Fatality Ratio, CFR ,of the virus, commonly called a case fatality rate, although it isn’t technically a rate but a proportion. On 10 April 2013, 33 human cases of infection with influenza A(H7N9) virus have been reported in four provinces of China: Shanghai (15), Jiangsu (10), Zhejiang (6) and Anhui (2). since 31 March 2013, with onset of disease between 19 February and 3 April 2013. The date of disease onset is currently unknown for five patients. Nine patients died.

That means that the current CFR = 27%, but there are still 21 are severe cases and three are mild cases. The median age is 64 years with a range between 4 and 87 years; 11 of them are females.

To calculate CFR, you can only count resolved cases, that is, people who have recovered or died. We don't know for sure how many are still in hospital, but it appears to be a large number, many in critcal condition. Even if some of these survive, they obviously would not have without advanced care. This will not be available in a severe pandemic.

The true CFR of this virus could become as high as 90%. To decrease the CFR significantly, we would have to assume thousands of unreported mild cases. If this is true, we will see cases in other countries very soon.

We are either looking at a virus which is already pandemic-ready or at a virus with a 90% kill rate which is 2 mutations away from pandemic status. I would actually prefer the former as the latter is a potential species-wiper.

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Update H7N9 AI outbreak in China, ECDC, April 11, 2013

  1. 1. http://www.ecdc.europa.eu/en/press/news ECDC Portal > English > Media Centre > NewsEpidemiological update of 11 April: novel influenza A virus A(H7N9) inChina11 Apr 2013On 31 March 2013, the Chinese health authorities announced that they identified a novel influenza A(H7N9) virus in three ECDCseriously ill patients.As of 10 April 2013, 33 human cases of infection with influenza A(H7N9) virus have been reported in four provinces of China:Shanghai (15), Jiangsu (10), Zhejiang (6) and Anhui (2). since 31 March 2013, with onset of disease between 19 February and 3April 2013. The date of disease onset is currently unknown for five patients. Nine patients died (case-fatality ratio=27%), 21 aresevere cases and three are mild cases. The median age is 64 years with a range between 4 and 87 years; 11 of them arefemales.No epidemiological link has been identified among cases. Almost 700 close contacts of the confirmed cases are being closelymonitored. There are reports of a potential small family cluster of disease around the first case, but this has not been confirmedby laboratory data. In Jiangsu, investigation is on-going into a contact of an earlier confirmed case who developed symptoms ofillness.The source of these infections and the mode of transmission are yet to be determined. This is the first time that human infectionwith influenza A(H7N9) virus has been identified.The Chinese health authorities are responding to this public health event by enhanced surveillance, epidemiological and laboratoryinvestigation and contact tracing. The animal health sector has intensified investigations into the possible sources and reservoirs ofthe virus. The authorities reported to the World Organisation for Animal Health (OIE) that A(H7N9) was detected in samples frompigeons and chickens and in environmental specimens from three markets in Shanghai. These markets have been closed and thelive poultry were culled.The influenza A viruses from the first three cases were non-subtypeable and were sent to the WHO Influenza Collaborating Centreat the Chinese Centre for Disease Control and Prevention (CCDC). The genetic comparison indicated that these cases were causedby a novel reassortant avian influenza virus with avian origin genes from both A(H7N9) and A(H9N2). No similar viruses have beenseen before and A(H7N9) differs from A(H7) and A(H9) viruses that have been seen previously in Europe.No vaccine is currently available for this subtype of the influenza virus. Preliminary test results suggest that the virus is susceptibleto the neuraminidase inhibitors (oseltamivir and zanamivir).At this time there is no evidence of on-going human-to-human transmission and there has not been further geographical spread.More sporadic cases are expected to be reported. The risk of disease spread to Europe is considered low, although individualcases coming from China cannot be ruled out.Figure 1: Distribution of influenza A(H7N9) cases by date of onset, age, gender, status and province, China, as of10 April 2013 (n=33)*Date of Age Sex Status Severity Provinceonset19/02/2013 87 M dead severe Shanghai27/02/2013 27 M dead severe Shanghai07/03/2013 38 M dead severe Zhejiang15/03/2013 35 F dead severe Anhui19/03/2013 45 F alive severe Jiangsu19/03/2013 48 F alive severe Jiangsu20/03/2013 83 M dead severe Jiangsu20/03/2013 61 F alive severe Jiangsu21/03/2013 32 F alive severe Jiangsu21/03/2013 79 M alive severe Jiangsu22/03/2013 67 F alive severe Shanghai25/03/2013 67 M alive severe Zhejiang25/03/2013 59 M alive severe Shanghai27/03/2013 52 F dead severe Shanghai28/03/2013 48 M dead severe Shanghai28/03/2013 74 M alive severe Shanghai28/03/2013 55 M alive severe Anhui28/03/2013 85 M alive severe Jiangsu29/03/2013 64 M dead severe Zhejiang29/03/2013 66 M alive mild Shanghai29/03/2013 67 M alive mild Shanghai
  2. 2. 29/03/2013 70 M alive severe Jiangsu30/03/2013 25 F alive severe Jiangsu31/03/2013 4 M alive mild Shanghai01/04/2013 64 M dead severe Shanghai01/04/2013 62 M alive severe Shanghai02/04/2013 74 M alive severe Jiangsu03/04/2013 77 M alive severe Shanghai? 51 F alive severe Zhejiang? 79 M alive severe Zhejiang? 65 M alive severe Zhejiang? 76 F alive severe Shanghai? 81 F alive severe Shanghai*Date of onset is currently unknown for five patients.Figure 2: Distribution of influenza A(H7N9) cases by week of onset of symptoms, China, as of 10 April 2013 (n=28)Figure 3: Distribution of cumulative number of influenza A(H7N9) cases by province, China, 19 February 10 April2013
  3. 3. Read more: ECDC Rapid Risk Assessment Severe respiratory disease associated with a novel influenza A virus, A (H7N9) China, 2 April 2013 Epidemiological update 10 April 2013: novel influenza A virus A(H7N9) in China Epidemiological update 9 April 2013: Novel influenza A virus A(H7N9) in China Epidemiological update 5 April 2013: Seven new confirmed cases of novel influenza A virus, A(H7N9) in China Epidemiological update 3 April 2013: Six new confirmed cases of novel influenza A virus, A(H7N9) in ChinaExternal links: WHO: question and answers on human infection with influenza A(H7N9) virus, China (updated 5 April 2013) Chinese Center for Disease Control and Prevention: question and answers about human infection with A (H7N9) avian influenza virus (published 31 March 2013) Share European Center for Disease Prevention and Control (ECDC) 2005-2013http://www.ecdc.europa.eu

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