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The WHO has raised the status of the global swine flu situation to 6, the highest level, and officially declared the outbreak a global pandemic.
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:
“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).
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.
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.
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.
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.
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,, 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.”