Wednesday, March 01, 2017

WHO Virtual Press Conference On H7N9

Credit CDC


The World Health Organization held a virtual press conference this morning on avian flu (primarily H7N9 in China), where three flu experts provided updates, and fielded questions, on this season's H7N9 and H5Nx outbreaks around the world.

Speakers were Dr Wenqing Zhang; Head, Global Influenza Programme, WHO HQ along with Dr Jackie Katz; Director, WHO CC, CDC Atlanta, USA and Dr. Yuelong Shu; Director, WHO CC, China CDC, Beijing, China.

An audio file of the 50 minute meeting has now been posted at HERE.

You'll find the opening remarks from Dr. Wenqing Zhang (see below), and we get some important revelations from the Q&A session.

Spurred on by a question posed by Helen Branswell regarding the physical sharing of virus isolates from China, we learned that China has not allowed the export of any H7N9 virus isolates to outside labs since 2013.  Presumably this includes other subtypes as well.

Sequences have been deposited at GISAID, but the actual viruses have not been shared.  Something which is considered vital under the WHO's Pandemic Influenza Preparedness (PIP) Framework, which was adopted and approved by all member nations in 2011. 

Walking a delicate diplomatic tightrope, the WHO panel praised the cooperation of China's CDC, assured that progress is being made, and said they are hopeful this impasse will soon be broken.The license to export is apparently granted by another agency, and is not up to China's CDC.  

You'll find a deeper discussion of the challenges in getting full disclosure of global health threats in Adding Accountability To The IHR.

Additionally, we learned that H7N9 has recently split into two lineages, one of which appears to have shifted antigenically away from our current stockpile of H7N9 vaccine.  We may learn tomorrow whether a new candidate vaccine will be recommended by the WHO, when they announce their recommendations for next fall's seasonal flu vaccine.

And lastly, we are informed that while roughly 7% of human infections with H7N9 have shown  resistance to neuraminidase inhibitor (NAI) antiviral drugs (like oseltamivir aka Tamiflu ®) , nearly all of those infections appear to have developed resistance while receiving treatment.

Only one environmental sample has reportedly carried the resistance mutation.

While of obvious concern to the patients being treated, and occurring at a substantially higher rate than we usually see with seasonal flu (roughly 1%), spontaneous mutations within a patient receiving antivirals are far less worrisome than finding biologically `fit' resistant viruses in the wild.

The (emailed)  opening remarks from Dr. Zhang follow:

 1 March 2017

Thank you Christian and thanks to the journalists for joining us on the line.

Today, we would like to provide an update on influenza H7N9 and other avian influenzas, giving you the current situation: what is different from previous years, what the associated risk is, and what WHO’s recommendations and actions are. We are taking the opportunity of doing this because of the presence in Geneva this week of directors of two WHO Collaborating Centres on Influenza. They will speak with you as well.

Risk assessment

Before we get into the details, our core message is that the risk of sustained human-to-human transmission of H7N9 remains low, as it does for other subtypes of avian influenzas. However, constant change is the nature of all influenza viruses, and that is why we follow the developments so closely.

H7N9 in humans this year

WHO constantly monitors zoonotic infections, meaning infections in animals that can naturally transmitted to humans. This year, we have closely followed the fifth wave—which is the current wave—of H7N9 in humans. H7N9 is an avian influenza that was first reported in 2013. From October 2016 to today, there have been a total of 460 laboratory-confirmed human infections with A(H7N9), reported to us from China. The number exceeds previous seasons and accounts for more than 1/3 of total cases since 2013. However, the epidemiological characteristics of human infections, such as the sex ratio, exposure history, case fatality rate, the median age of human cases … remain similar to previous waves.

What is new 1?

In this 5th wave, viruses from about 7% of human cases have had genetic markers associated with resistance to neuraminidase inhibitors. Neuraminidase inhibitors are a category of antivirals, including Oseltamivir, for case management (or treatment) of influenza infection.  This rate is similar to previous waves. Although a slight increase was observed, it is still lower than that of 1st wave according to data from WHO Collaborating Centre in China CDC Beijing. Notably, since 2013, except for one environmental virus, all antiviral resistant viruses were from human cases.
From information available, most cases were sampled after treatment with antivirals. This means that most of the resistant viruses were developed after the use of antivirals in patients, and not before.  WHO is closely monitoring these developments. So far there is no evidence to recommend changes in clinical management of the infection.

What is new 2 ?

Based on genetic information available in the GISAID EpiFlu database, which is a publically accessible database that gathers information of influenza viruses from around the world, viruses from 3 recent human cases and 1 environmental specimen have changes. These changes make the virus highly pathogenic in birds, meaning that it can cause some severe disease in birds. Previously, H7N9 had only been observed to be “low pathogenic” in birds, meaning the virus did not cause visible outbreaks of disease in birds.

Again, classification of pathogenicity here refers to birds, not to humans. At this time, there is no evidence that these changes in the virus affect its pathogenicity or transmissibility in humans.

Other avian influenza viruses
A quick note on other avian influenza viruses: aside from H7N9, H5 viruses in the format of H5+N1, 2, 3, 5, 6, 8 and 9 continue spreading in avian population, though so far only H5N1 and H5N6 cause human infections. The assessment of the risk of sustained human to human transmission of the H5 viruses remains low.

WHO response

Since 2003 with the emergence of the highly pathogenic avian influenza H5N1, WHO has been providing updates of the situation, the risk assessment and risk management recommendations to Member States on avian influenza.

WHO, working through the Global Influenza Surveillance and Response System (GISRS), in collaboration with the agricultural and animal health sectors and organizations such as FAO, OIE, as well as other institutions, has been closely monitoring the virus evolution, conducting risk assessment, updating laboratory diagnostics, strengthening surveillance globally and adjusting control measures, such as selecting and developing new candidate vaccine . WHO is also strengthening capacity in countries, and negotiating access to pandemic vaccines and stockpile of antivirals.  And we will continue this work.


WHO’s prevention advice remains the same: avoid, if possible, poultry farms, contact with animals in live bird markets, entering areas where poultry may be slaughtered, or contact with any surfaces that appear to be contaminated with faeces from poultry or other animals. Follow good hand hygiene and food safety practices: wash your hands often with soap and water, cover your mouth and nose when coughing or sneezing, cook food thoroughly.


The risk of sustained human to human transmission of H7N9 and H5 avian influenzas remains low. It is highly likely that further sporadic cases will continue to be reported, as long as the viruses continue circulating in poultry. WHO, through its Global Influenza Surveillance and Response System (GISRS) and working with other partners, is monitoring the situation very closely. Constant change is the nature of all influenza viruses – this makes influenza a persistent and significant threat to public health.

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