FROM THE UK AND AUSTRALIAN SCIENCE MEDIA CENTRE
The World Health Organisation has reported seven people in China have contracted Influenza A H7N9, including two deaths. Currently the source of the outbreak is unknown and there is no evidence of human-to-human transmission. This type of influenza is part of a group that is known to circulate among birds but no human cases of H7N9 had been reported until now. A WHO resource on H7N9 link is available at the end of this article. Below, UK and Australian experts comment on the current situation.
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Professor Robert Booy is Head of Clinical Research at the National Centre for Immunisation Research & Surveillance (NCIRS) based at the University of Sydney.
Will a pandemic result?
“Based on the information available, a pandemic is most unlikely due to H7N9. There are reported to be some mutations suggestive of mammalian adaptation but that is a long way from changes required for human to human spread, which importantly has not been observed.
What is the virulence of the organism and how likely is it to transmit between humans?
“It's virulence is unclear. If, as appears the case, it is infecting birds but causing few symptoms, it is quite different to the Highly Pathogenic strain of H5N1 about which we have been concerned for 15 years. The apparent high death rate at present is of concern. More people with milder symptoms need to be tested to determine if we are only seeing the tip of the iceberg of a more widespread mild infection.”
Will routine influenza vaccination provide any cross cover?
“We cannot say if routine flu jabs or past flu infection might provide cross-protection. Simplistically, one would not expect cross protection against such a remarkably different virus, but we have some evidence that it occurred with the past three pandemics so it is not out of the question.”
Additionally:
“It should be said that the Chinese have acted promptly and with vigour. I have no doubt they will rapidly institute major containment measures such as large-scale poultry culling if that is the source of this series of cases. They have everything to gain by transparency with real-time updates for their own people and the wider world. We may live in a time where disease can rapidly and widely disseminate but equally information and intelligence are also spread at high speed to enable decisive action.”
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Professor Adrian Sleigh is from the National Centre for Epidemiology and Population Health at The Australian National University
“The 3 deaths [ed: now updated to 5] from H7N9 flu virus is of some concern. The H7 family of viruses are bird flus that have crossed to poultry workers many times (respiratory infection and conjunctivitis) – but usually as benign infections. In 2008 Jessica Belser published evidence that H7 viruses were becoming more transmissible among humans. In March this year the Australian Government reported to WHO a small outbreak of H7N7 on a poultry farm in NSW, which was ‘stamped out’. Now we have to wait to see if the is any interaction among the cases in China or indeed any evidence of human-to-human transmission. Each case must be investigated for recent exposure to other sick people or sick birds and all local bird flocks must be checked too.”
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Associate Professor Ian M Mackay is a Group Leader in the Clinical Medical Virology Centre within the School of Chemistry and Molecular Biosciences, University of Queensland. He has produced the following web resource on H7N9: http://www.uq.edu.au/vdu/VDUInfluenza_H7N9.htm
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Dr John McCauley, Director of WHO Collaborating Centre on Influenza, Division of Virology, MRC National Institute for Medical Research, said:
“A new strain of influenza virus affecting humans has been recently identified in eastern China by the Chinese Center for Disease Control and Prevention, one of the WHO Collaborating Centres for Reference and Research on Influenza, part of the WHO Global Influenza Surveillance and Response System. The first three cases showed disease symptoms between 19 February and 15 March.
“The virus belongs to the A(H7N9) sub-type, a sub-type that has not previously infected humans, and has emerged from the reservoir of avian influenza viruses. The cases have been in the Anhui and Jiangsu provinces and in the city of Shanghai. The number of laboratory-confirmed human cases currently totals seven - three have died of the infection.
“It is not known how the virus was transmitted to these seven individuals. By identifying the source of infection measures can be taken to reduce human exposure to this new virus. The Chinese Center for Disease Control and Prevention is investigating whether there has been any human-to-human transmission.
“Analysis of the three virus isolates at the Chinese Center for Disease Control and Prevention has shown that the viruses are sensitive to the anti-influenza drugs that target the virus neuraminidase, Tamiflu and Relenza. ”
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Dr Alan Hampson is an influenza consultant and Chair of the Australian Influenza Specialist Group
“At the moment it’s very hard to have any real idea of what is happening but the reports are certainly concerning. There is a virus out there which, like the H5N1 strain, appears to be causing serious illness, but how widespread that illness is at this very early stage, we don’t know. We don’t know whether we’re seeing the tip of the iceberg or whether we’re actually seeing most of the existing cases presenting as severe infection. If it’s the latter then it’s a concern. The other thing to consider is, of course, that there is no obvious source of the virus at the moment. Undoubtedly it’s going to turn out to be domestic poultry, but whether it’s chicken or ducks we don’t know. In the case of H5N1 in Thailand and Vietnam in 2002/03 when people started to become ill, it was only after that that it was recognised that the virus was actually causing significant outbreaks in poultry. So maybe in the fullness of time it will be found this virus is also causing severe disease in poultry. If it isn’t and it is being transmitted among poultry without any obvious signs then that’s going to make it very difficult to get any idea of how you might control it, we have to wait and see and we have to wait to see if this is the tip of the iceberg in humans.”
About the particular H7N9 strain:
“The H7 virus has been known to cause mild infection in humans and to cause severe infections in poultry. But the particular neuraminidase type [the N in H7N9] of this virus is different than we’ve seen reported. There have been 3 other neuraminidase types associated with the infections that have been in poultry and have transmitted to humans. So in this H7N9, the N9 is the different aspect of this, and whether that is contributing something to the virulence, we don’t know.”
Will this affect Australia’s flu season or lead to a pandemic?:
“No, we really hope not. If a virus starts to transmit among humans then there’s no telling how quickly it might travel and where it might travel too. We really don’t know, it’s very early days to know what we’re dealing with at this stage. Does it have pandemic potential? Yes, any influenza that jumps from an animal species to a human has pandemic potential. If it learns to spread in humans, if it actually acquires that ability, then it’s a high likelihood it will become pandemic. Can we do much about it? The world improved its pandemic responsiveness after the H1N1 outbreak, but I think we have a long way to go in learning about this new strain.”
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Dr Jenny McKimm-Breschkin is Virology Project Leader at CSIRO Materials Science and Engineering
While poultry and pigs are infected globally with various strains of influenza, and there are isolated cases of human infection by direct contact, usually the disease is mild. It is of more concern when those infected are dying or seriously ill as seen with this new virus. Humans have not been exposed to an H7N9 strain of virus, hence there is no immunity to this strain. This means humans would be much more susceptible to H7N9 infections that to the commonly circulating seasonal strains of flu.
However, at the moment while this virus may have spread from poultry or pigs to humans, it is not clear whether it can be transmitted from human to human. If this were the case, this could lead to more widespread infection with this new strain, and concerns are that it could lead to a “pandemic”, which occurs when there is no immunity to a new strain. As always with flu, it is unpredictable. Although the H1N1 pandemic was milder than feared, it gave the world a practice run for dealing with new pandemic strains. This will hopefully expedite implementation of strategies for minimisation of the impact, with faster delivery of drugs and development of vaccines when needed.
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Professor Dominic Dwyer is a medical virologist and Director of the Institute of Clinical Pathology and Medical Research at Westmead Hospital, NSW
“The World Health Organisation (WHO) laboratories in Australia (the WHO Collaborating Centre is based in VIDRL, Melbourne; Westmead Hospital in Sydney, and PathWest in Perth) are closely watching this situation. Although this influenza subtype is not present in Australia, these, and other public health laboratories in Australia, have developed molecular tests to identify this virus should people be ill after returning from this part of China.”
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Dr Nikolai Petrovsky is an Adelaide based clinician, vaccine researcher and Director of Endocrinology at Flinders University
“The worry is that this outbreak has happened at different sites in China so suggests that this virus must be spreading rapidly though the bird populations in these regions. As yet no surveillance data has been released on what is happening with this virus in the bird population. If this turns into a real threat then all stockpiled bird flu vaccines on which the U.S government has spent billions will be useless as this is a different strain (H7N9) to the stockpiled vaccine (H5N1).
Hopefully as with H5N1 this new variant will not acquire the ability for human to human transmission – however if it does, it could cause the next major human influenza pandemic. Yet again this demonstrates the woeful inadequacy of influenza surveillance and response mechanisms – and ongoing difficulties of relying on the Chinese to provide timely warning to WHO and the rest of the world when these instances happen. In one of these events were to turn into a pandemic, which will happen one day, every day of advance warning might translate into hundreds of thousands, if not millions, of lives saved or put at risk. The current situation is like warning of a tsunami weeks after it has occurred – simply not good enough.”
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Professor Anton Middelberg is a Smart Futures Premier's Fellow and Deputy Director of Bioengineering at the Australian Institute for Bioengineering and Nanotechnology at The University of Queensland. He is actively researching new technology for rapid vaccine development, including against influenza (and other diseases).
“The latest outbreak of H7N9 in China reminds us that we live in a region where disease regularly re-emerges. It also reminds us that there is presently no technology that can quickly and cost-effectively mass manufacture vaccine. Although the WHO is sending materials for vaccine development to China, it is unlikely that vaccine will be produced quickly enough to impact this outbreak. It is therefore critical to rely on other methods such as handwashing, as per the WHO information sheet.
While Australia has a domestic capacity to make vaccine in eggs, the 2009 Swine Flu pandemic showed how strikingly slow this historical approach can be. The H7N9 strain of influenza presents a particular challenge, as H7N9 is not included in the current annual vaccine compositions that many Australians receive. It is unlikely, based on our learnings from 2009, that Australia will be able to manufacture vaccine quickly enough to impact this situation, should it not be adequately controlled in China through hand washing.”
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