April 27, 2009

experts comment on swine flu

An outbreak of swine influenza in Mexico has raised fears of a possible global flu pandemic, as the virus has shown the ability to pass between humans. As of the beginning of the week, at least 100 people were believed to have died (although this number was not confirmed) with further cases reported in the US and Canada. Health officials in the UK have been warned to prepare for cases in this country.

Sandra Mounier-Jack, Lecturer in Health Policy, London School of Hygiene and Tropical Medicine, said:

“This new H1N1 outbreak is highly significant. WHO declared a new virus of Swine Flu H1N1 “a public health emergency of international concern, under the International Health Regulations” on 25 April 2009. However there is no need to panic and WHO and national governments’ advice should be followed.

“To date there remain many uncertainties:
,1. On the epidemiology of the disease, notably on the number of persons that any infected person is likely to infect, age group of those infected and the mortality rate and the causes of death. Reason for more deaths in Mexico vs. US is unclear but could be:
a) agent, ie the virus is different (unlikely)
b) the host is different (eg nutrition status) again, unlikely
c) the context is different (eg better health access, care in US)
d) statistical issue, most likely – different populations infected, different populations known

,2. On the evidence of possible interventions: we know that this virus is susceptible to antivirals Oseltamivir (Tamiflu) and Zanamivir but we do not know whether existing seasonal vaccination would be to partially protective against it. Some countries are already using public health measures such as screening passengers at borders or planning to quarantine them, while other are not.

,3. On the behaviour of populations and their compliance.

“From available information, it seems that the new H1N1 virus is well transmissible from human to human and has already spread to several countries, and therefore containment seems unlikely.

“Since 2005, countries all over the world have invested significant resources in preparing for an influenza pandemic, notably developed countries. Many countries have stockpiled antivirals, although how to deliver them within maximum of 48 hours remains a huge challenge. However preparedness levels in middle income and lower income countries remain low. Therefore it is likely that this flu outbreak will also be a test for global solidarity.

“This new outbreak will be a critical time for countries to test their response and notably the response of their health care system.”

Jeff Evans, Senior Lecturer Disaster Healthcare, University of Glamorgan, said:

“”Why is pandemic influenza (flu) different from normal flu? Normal flu is often termed seasonal flu and outbreaks occur almost every winter. Pandemic flu is slightly different for two reasons;
,1. it crops up every 10 – 30 years or so
,2. it is particularly virulent and has an ability to overcome a person’s natural defences. This means that it causes a higher degree of morbidity and mortality. In addition it also means that more people are affected than with seasonal flu. This is why it is termed pandemic.

“The UK has been preparing for an outbreak of pandemic flu for many years and plans are exercised and refined regularly. This means that the healthcare system, local government services etc are well placed to respond to H1N1 influenza if does become a pandemic. However, the biggest resource for dealing with a pandemic flu outbreak is the public. Self reliance is going to have to play a big part.

“Judging by previous outbreaks, we can expect to see anything up to a 150% increase in use of healthcare services; this will be coupled with a loss of healthcare workers due to staff either having flu themselves or taking time off work to look after family members (some estimates put the loss of healthcare staff at 30%).”

Prof Robert Souhami FMedSci, Foreign Secretary, Academy of Medical Sciences, said:

“The UK is recognised as one of the most prepared countries in the world for an influenza outbreak, however the situation in Mexico has shown just how important it is to continue research into infectious diseases. Up-to-date scientific information should be central to the Government’s decision-making process. It will ensure we are prepared not only for a possible influenza pandemic, but also for any future emerging infectious diseases which may affect the UK.”

Prof Angela McLean, Director, Institute for Emerging Infections, University of Oxford, said:

“From the point of view of a global pandemic the important question now is what will happen with the newly seeded epidemics outside Mexico? Will they be self-limiting, can they be contained by local interventions or are they growing and causing widespread community outbreaks? Because influenza spreads onwards and makes people ill very soon after infection those situations should become much clearer within a week or two. If there are large outbreaks it will be important to know which age-groups are worst affected and how unwell they are. Once that information is available it will be possible to make a considered response to this situation. Until then substantial uncertainty is, sadly, all we can be sure of.”

Keith Plumb, Fellow of the Institution of Chemical Engineers, said:

“Let’s keep things in perspective. This is not 1918; and with over 30 million doses of antiviral treatments, effective against H1N1 available in the UK right now we are well placed to combat any outbreak. We should also bear in mind that there are two flu-vaccine manufacturers in the UK (Novartis and Medimmune) and whilst there may be capacity issues, both companies are technically capable of producing appropriate vaccines.

“There is no evidence of pandemic in Europe at this point in time but should the threat increase, the UK has a wealth of scientific and engineering expertise which can be deployed to ramp up the countermeasures necessary to protect the population at large. Ultimately, the problem won’t be solved by government or some sort of national security clampdown – it’s the medical profession supported by engineers and scientists who will see us through.”

Keith Plumb is also Technical Chairman of the Biocontainment, Biosafety and Biosecurity 2009 conference currently taking place in London.

Dr Anne Bridgen, Department of Biomedical Sciences, University of Ulster, said:

“These porcine H1N1 viruses are quite antigenically distinct from the human H1N1 so there is not likely to be much protection from human H1N1 vaccines, and even less from more distantly related viruses. Pity, I was hoping they would offer some protection too as human H1N1 is part of the current influenza A virus vaccine.”

Prof Ian Jones, Professor of Virology, School of Biological Sciences, University of Reading, said:

“The current vaccine is made up of three Influenza strains to reflect currently circulating human influenza; that is a H1 virus, a H3 virus and type B virus. The recommended vaccines for use in the 2009-2010 influenza season (northern hemisphere winter) from WHO are made up of an A/Brisbane/59/2007 (H1N1)-like virus; A/Brisbane/10/2007 (H3N2)-like virus; and B/Brisbane/60/2008-like virus.

“The response to the vaccine in vaccines is made up of two components, antibodies and T cells. Antibodies provide protection while T cells generally shorten the period of infection.

“Although the current swine flu is a H1 it is only 85% related to A/Brisbane/59/2007. This relatedness is lower than many yearly changes in flu vaccines so it is doubtful that the current advised vaccine strain would be effective against it in the production of antibodies. The T cell response is, however, likely to be cross reactive. The most likely result is that a current vaccination would not stop you from being infected but might reduce the severity of the symptoms.”

Prof Nigel Dimmock, Emeritus Professor of Virology, University of Warwick, said:

“What was swine flu is now human flu. The next 1-2 weeks will tell us whether or not this flu has the capacity of pandemic spread. However, even if it doesn’t, the virus still has the option of improving its fitness to spread by mutating – Darwin was right!”

Prof Paul Hunter, Professor of Health Protection, School of Medicine, Health Policy and Practice, University of East Anglia, said:

“Swine influenza virus H1N1 is not the same as the human influenza virus H1N1 and is actually quite distinct. The clinical illness is however generally similar.

“One of the problems with swine flu is that the vaccine has a reputation of causing serious side effects. In 1976 an outbreak of swine flu in the US led to about 1/4 the population being vaccinated. An estimated 500 cases of Guillain-Barré syndrome with 25 deaths followed that were attributed to the vaccine. There were more deaths from the vaccine than from the outbreak. This is why people are talking about the use of antivirals rather than vaccine to control the outbreak.

“Although it is always very difficult to predict the course of an outbreak this early on, the fact that cases are already being reported from around the world is of concern. This suggests to me that the virus certainly does have epidemic potential. Without a widely available effective and safe vaccine, it would be difficult to do much to control the spread, though those countries like the UK with large stockpiles of antivirals will be able to reduce the severity of any impact and also reduce further spread of the infection.

“The important thing is that people with a flu-like illness, especially after returning from an area where cases have been reported, avoid contact with other people, phone their doctors rather than turn up.

Further advice is contained in the HPA website

or the US CDC site“

Dr Steven McOrist, of UK Pig Veterinary Society, said:

“British veterinary groups have a responsibility, besides surveillance of our pig’s health and reassurance on food quality, to ensure that our main efforts are to work to prevent the introduction of this virus into the UK pig population. We therefore fully support all public health warnings and advice to contain the spread of the new human flu virus.

“While the new strain of human flu virus does contain some elements of swine flu strains, it has never been isolated from any pig in Mexico or the USA. There are no current reports of any significant swine flu issues in Mexican or US pigs. The actual “re-assortment vessel” where the new human strain developed is therefore not yet clear, it may have been in pigs or in wild fowl, poultry or humans.”

Dr Noemi Eiser, Honary Medical Director at the British Lung Foundation, said:

“People who have recently been to Mexico and are displaying any flu like symptoms such as a fever and aches and pains should seek medical advice immediately. This also applies to anyone who has been in close contact with people who have been in Mexico.

“There is no need to panic about swine flu. However, everyone should continue to take sensible precautions to help avoid the spread of all air-borne respiratory infections. This includes washing your hands and coughing and sneezing into tissues and disposing of them immediately.”