Overnight the World Health Organisation raised the status of the A(H1N1) virus to phase 6 and is now officially treating it as an influenza pandemic.
The WHO’s Director General, Dr Margaret Chan said that while the virus was having “moderate severity” in well-off countries, a bleaker picture would emerge “as the virus spreads to areas with limited resources, poor health care, and a high prevalence of underlying medical problems”.
“Spread in several countries can no longer be traced to clearly-defined chains of human-to-human transmission. Further spread is considered inevitable.”
The Australian and UK Science Media Centres wrapped up comment from experts overnight:
Professor Adrian Sleigh is from the National Centre for Epidemiology and Population Health at The Australian National University
“Pandemic infections are epidemics that are spreading through populations in many parts of the world. They are widespread because conditions were suitable for spread and many people were susceptible to infection. They may or may not be serious infections.
The current H1N1 influenza has been a mild infection in Australia so far. Its pandemicity and its seriousness are separate properties – and so far it is pandemic but not more serious than normal seasonal influenza. In the past other pandemic flu viruses have been more serious than the seasonal variants they replaced; it is too early to say this won’t happen again with the current pandemic H1N1 but so far this pandemic strain has been mild in its effects.”
Prof Chris Burrellis Emeritus Professor of Virology at The University of Adelaide
” The important thing to stress is that this reflects the extent of the global distribution of infection but it says nothing about the severity of it. There still has not been any suggestion that it is becoming more severe and the vast majority of infections have not needed to go to hospital and have not been particularly unwell at all.
In Australia each state sets its own policy and level of containment depending on the number of cases they have got and they set their quarantine requirements for people coming from other areas depending on the particular area they are arriving from. Victoria, with the vast majority of cases, is having to handle this in a different way to South Australia at the moment.
Declaring this a pandemic is a reflection of the global distribution and it may also be a reflection of how far they predict it may spread in a geographical sense around the world but at this point it says nothing about the severity of it.”
Prof Raina MacIntyre is Professor of Infectious Diseases Epidemiology and Head of the School of Public Health and Community Medicine at the University of NSW. She sits on the Scientific Influenza Advisory Group to the Chief Medical Officer of Australia and is an expert in influenza and emerging infectious diseases.
“The WHO definition of Phase 6 is evidence of sustained community transmission in one country in an additional WHO region (over and above the requirements for phase 5). According to this definition, we are technically already in Phase 6 and have been so for a while. The WHO phases, however, are guides rather than absolute rules, and do not factor in severity of the infection. The fact that the epidemic is not as severe as initially feared, as well as trade and economic implications of declaring Phase 6, may also have been factors in the decision. In addition, the question of this being a H1 virus is also relevant – traditional thinking about a pandemic dictates that a pandemic virus has a new H type (eg H5, H7) previously not seen in humans. Swine flu is H1N1, which is not a new H-type, but a severely drifted H1. So whether this meets the definition of a pandemic virus is also questionable. These factors all combine to make the current situation quite complex.”
Dr Vince Hooper is from Banking and Finance at the Australian School of Business, University of New South Wales. He is able to comment on risk influences on emerging markets.
“Sydney has a mountain range of high rise apartment blocks, many with garbage chutes which could be a potential transmission mechanism for the virus if they are not properly and hygienically cleaned frequently. It is important that the Health Department has guidelines for Body Corporates to implement safe and coherent waste removal and hygiene strategies, not only to prevent the spread of the swine virus but also other pathogens. We have to remember this is an airborne transmitted disease and has the potential to cost the Australian economy around 5% of GDP if it really takes hold. According to World Bank figures this pandemic could cost the world economy $3trillion in lost GDP.”
Dr Mark Lawrie is President of the Australian Veterinary Association.
“It is important to reemphasise the need for ongoing improvements in biosecurity across human and animal health sectors. Within the veterinary sphere, this is a key focus following recent outbreaks of Hendra virus and equine influenza here in Australia. In respect to Influenza A (H1N1), our recommendations, which have been supported by the pork industry, are to monitor and further improve biosecurity within that industry, to raise awareness of the risk of the infection spreading from humans to pigs and, potentially, vice versa. This will become more crucial as the number of human cases increases.”
“Regardless of the pandemic situation, pork meat, appropriately cooked, canned or cured, is safe for people to eat.”
Professor Nikolai Petrovsky is Research Director, Vaxine Pty Ltd
“The recent establishment and spread of swine flu within the Southern hemisphere (predominantly Australia) having originated in the Northern hemisphere, confirms that swine flu is with humans to stay and thereby satisfies all criteria to be officially listed as a ‘influenza pandemic’. The label of a pandemic does not refer to the severity of the infection but rather its ability to spread throughout the human population of a new influenza strain that has its origins in a non-human species, in this case swine. These influenza pandemic events happen with a periodicity of 20-30 years and each of the current seasonal H1 and H3 influenza strains had its origins in an initial pandemic. The implications are that it is almost certain that the new swine flu strain will join existing H1, H3 and B influenza strains as an indefinitely circulating season human influenza strain.
Given the widespread establishment of swine flu in the human population is now inevitable, the question is now just not whether a monovalent vaccine against the new swine flu strain will need to be developed, but just as importantly should we start thinking about developing a new quadrivalent seasonal flu vaccine incorporating the existing 3 H1, H3 and B strains and in addition the new H1 swine flu strain. Vaxine Pty Ltd, a research organisation based within Flinders Medical Centre in Adelaide and funded by the US National institute of Health has previously successfully developed a quadrivalent vaccine covering H1/H3/B and H5 influenza strains, thereby providing protection against both avian pandemic influenza plus seasonal influenza. The Vaxine team is now applying the knowledge generated in development of the first combined seasonal/pandemic vaccine to develop and test a new quadrivalent vaccine including H1/H3/B and swine H1 strains that could then effectively counter all major flu strains including swine flu currently circulating in the Southern hemisphere and which will inevitably return to cause further disease in the Northern hemisphere when they re-enter their next flu season in six months time.”
Dr Michael Skinner, Senior Lecturer in Virology, Imperial College London, said:
“The change in pandemic status does not reflect any change in the nature of the virus or the severity of disease; it remains relatively mild for the vast majority of those infected (WHO has classified it as ‘moderate’). It is a response to the fact that H1N1 is clearly spreading readily in the community in countries and regions outside of North America. Importantly this spread is notable in the southern hemisphere, and so is a picture we might expect in the UK next winter.
“The change places obligations on countries for planning, surveillance and public health responses. In many countries, such as the UK, such measures are already in place – others will find it easier to muster resources given the change in status. The announcement is unlikely to have practical implications for production of vaccines – activity was going ahead at full speed in the pre-production phase (with seasonal flu vaccine production continuing) and would anyway have moved shortly into mass production. The announcement will make it clear that careful planning for distribution and delivery of the vaccine, to those most in need, will need to go ahead.”
Prof Andrew J. Easton, Biological Sciences, University of Warwick, said:
1. Assuming the WHO raises the status, why is it a pandemic now and why was it not declared sooner?
“In order for the infection to be declared a pandemic it had to fulfil some specific criteria. In particular there had to be clear evidence that it was spreading in a ‘productive’ way. Compare this with SARS where the virus had a short period of generating human infections but spread was limited and the epidemic died out. It is clear that this strain of flu has been able to spread sufficiently that it is likely to become a worldwide epidemic (the definition of a pandemic).”
2. Why is swine flu spreading faster in places like Australia?
“The attributes of a specific virus and the specific factors which determine spread of that virus are very specific. These relate to the nature of the conditions in which the virus finds itself e.g. population density climatic conditions that may help the virus survive longer outside the body etc. These are very complex and not fully understood. It will be necessary to study the Australian situation in depth to try to determine what is important.”
3. Does the increased number of cases mean it has mutated into something more dangerous or is it likely to do so?
No to both. It is a result of the ability of the virus to spread per se. For the first part consider the situation where on average an infected individual infects 3 further people. In the early stages of an epidemic a small number are infected but with time that number increases very rapidly. i.e. initially 1 person becomes 4 with three of these infecting a further three each to give a total of 13 (9 new and the original 4) the nine new each generate 3 new infections giving a total of 40 (27 new plus the original 13) and so the numbers grow. For the second part we cannot predict the nature of mutational events in any meaningful way.
4. How many people in the UK are predicted to catch H1N1?
In a pandemic most of the population is likely to experience infection but precise numbers are not yet possible to predict.
5. How soon might a vaccine be available and will there be enough?
Once the virus has been established as a pandemic strain vaccine producers will direct production to an appropriate vaccine as soon as it is available. Currently it is expected that this might take up to 6 months. There will then be a period of time as the production increases to provide sufficient quantities.
6. Is the main threat now to infrastructure rather than directly to health and what is the expected economic impact?
On the basis that the cases to date have primarily experienced relatively mild disease (though there is variation in this) the major impact is indeed likely to be infrastructure and hence economic. The economic impact will be felt in terms of production losses but the scale is difficult to assess at the moment as it depends on the severity of the disease and the pace of spread of infection.
Prof Robert Dingwall, Director of Institute for Science and Society, University of Nottingham, said:
“It is important to remember that ‘pandemic’ is just the public health way of saying ‘there’s an awful lot of it about’. We do seem to be lucky that this is not a particular nasty virus, although it does look increasingly as though many of us will have a few extra days’ off work sometime this year as a result.”
Dr Adam Kamradt-Scott, Research Fellow, Public and Environmental Health Research Unit, London School of Hygiene and Tropical Medicine, said:
“What this latest announcement really seeks to do is to get governments all around the world to step up their response to the H1N1 pandemic by reviewing their plans and ensuring everything is ready in case this virus does mutate into a more virulent form. This declaration is recognition of what we’ve been aware of for some time – that the virus is continuing to spread internationally. We’re fortunate though that the virus is still only causing mild illness in most people it infects. At the moment therefore, what this means for the average person in the street is to continue doing what they’re hopefully doing already: paying attention to personal hygiene measures such as regular handwashing and making sure you cover your mouth when coughing or sneezing. There is no need to panic, and should you start to feel unwell, stay at home and phone either your doctor or the NHS Direct for further advice.”
Prof Ian Jones, Virologist, University of Reading, said:
“The announcement reflects the worldwide spread of the virus meaning that the definition of a pandemic has been met. However the virus itself has not changed so there is no reason at present to suggest anything but a mild albeit widespread infection.”
Dr Mark Fielder, a medical microbiologist at Kingston University, said:
“Pandemic status has been called now because the numbers of cases of Influenza A H1N1 has now reached a threshold value. This was not called before as the required criteria had not been met.
“The situation now is such that the number of cases, in a number of different countries, has reached the level that the World Health Organisation (WHO) term pandemic levels.
“This situation was, and is expected, and is part of the known disease process of influenza A. Cases of infection will continue to appear throughout the next few weeks or months as the disease spreads. As time progresses cases are likely to lessen as the natural immunity of the population develops and control measures are implemented. This situation is being managed on a local and international level and there is no need for panic.”
Why is swine flu spreading faster in places like Australia?
“There are members of the population that are seen by epidemiologists (scientists who study the occurrence and spread of disease) as being susceptible. These susceptible members of the population are potentially more likely to be affected by whatever agent is being discussed. In this case it might be that there are more people in some populations that are susceptible to influenza A. There can be a number of reasons for this ranging from underlying natural immunity, general health status, chance of exposure and so on. What must be remembered is that despite the increase in cases around the world and, apparently in some countries specifically, the number of deaths is still very low. Whilst this disease is spreading as was expected, associated mortality is low and there is no need for panic. National and international surveillance and control measures are in place and working.
“Now that Australia is entering into its winter season, cases might rise as a result of the influenza A infection. This is exactly what we see with influenza infections in winter in the rest of the world.”
To talk to these or New Zealand scientists about the influenza pandemic, please contact the Science Media Centre on tel: 04 499 5476 or email: email@example.com.