Swine flu: your questions answered
Updated on 30 April 2009
Channel 4 News online brings you our comprehensive question and answer guide to the swine flu outbreak.
Click here for the most recent and up to date answers to your questions.
Click on the links below to go to related questions. The answers provided are of a general nature. If you have a specific concern, you are advised to contact your doctor. -
- What is swine flu?
- Symptoms
- Risk groups
- Treatment and vaccines
- Prevention measures
- Pandemics
- Other
- Contributors
WHAT IS SWINE FLU?
What is it about this strain of swine flu that enables it to pass to humans, whereas previous strains (as far as I am aware) didn't?
Dr Adam Kamradt-Scott: Although rare, influenza viruses can undergo a substantial shift in mutation from time to time. When that occurs, and when humans are exposed to the new virus, there is the chance that it may change again, allowing it to pass easily between humans.
Download the Department of Health's swine flu leaflet here (.pdf).
Dr Meirion Evans: There are a small number of cases of swine flu each year around the world in individuals in direct contact with pigs. However, this new strain has developed the ability to spread from human-to-human. This is because it is a recombinant virus i.e. it has combined with a human flu strain. Those human elements in the gene give it the ability to pass between humans.
Dr John McConnell: We don't know yet.
Dr. Steven McOrist: It is misleading to assume that this human strain arose in pigs. The current north American influenza A outbreak is considered one of the pandemic human outbreaks, like Spanish flu or Hong Kong flu before it. The difference in this pandemic strain is that it appears to be capable of transferring from person to person.
Dr Mark Fielder: The influenza virus is able to replicate in humans, pigs and poultry which is why we have seen in recent times reports of bird flu and now swine flu. What we are seeing is a virus that has a natural host in one of these animals that has then, via mutation or natural genetic re-assortment, developed the ability to move into another species. In the case of this strand of swine flu (H1N1) this has also meant that this virus can move from person to person although early suggestions indicate that this transmission is not very effective.
Having said that, we must ensure we follow the advice of the Health Protection Agency which is the same for pretty much all respiratory infectious disease but is equally applicable for human swine flu.
How did the H1N1 virus get from pig to people and could it have happened in the UK?
Dr John McConnell: We don't know; and yes, perhaps.
Dr. Steven McOrist: Based on previous origins of new flu virus strains, one would suggest that it may have arisen in a situation where humans, fowl and swine come into very close contact. These may most often be small rural dwellings, wherein these three hosts all are located within the same small airspace. Exactly which host was the actual "reassortment vessel" is not yet clear.
Is there any evidence that this could happen to different sorts of animal-only infections/diseases/viruses?
Dr Adam Kamradt-Scott: There are a number of diseases that have passed to humans from animals. These diseases are called zoonosises. Humans have contracted Hendra virus, for example, from bats.
Dr Meirion Evans: It already has e.g. HIV, SARS.
Could it flare in late summer like the epidemic of 1918?
Dr Adam Kamradt-Scott: It is possible. We just don't know enough about the nature of the virus at this point.
Dr Meirion Evans: Yes. This is a possibility. We are now outside the normal flu season in the N hemisphere and one possible scenario is that this might fizzle out here over the next few weeks and return in the autumn as a full blown epidemic.
Will it mutate into something more deadly?
Dr Adam Kamradt-Scott: We are still waiting to see how the virus behaves. It may develop into a more lethal strain, or it may go the other way and become less so. We are still waiting to see.
Dr Meirion Evans: Unlikely.
Dr John McConnell: We don't know, but probably not.
Is swine flu any more dangerous than normal flu or does it just sound scarier?
Dr Meirion Evans: It's scary because we don't know for sure. It is likely to infect more people because most of the population will have no immunity to it. Whether it causes more severe illness than normal flu remains to be seen, but early indications are that outside of Mexico it has caused relatively mild symptoms. This may also be the cause in Mexico as well but the info coming out is very sketchy and heavily biased towards cases that have been admitted to hospital.
Dr John McConnell: Perhaps more dangerous in the sense that it might infect more people than seasonal flu because the general population will have limited immunity to the new virus. Will the illness be more serious than seasonal flu? Too soon to say, but evidence so far suggests not.
Dr. Steven McOrist: There will be inevitable debate about the origin of the new pandemic strain. These strains are due to a reassortment of animal and human viruses; in this case it appears to be a mixture of human, avian and swine origin.
What does the panel think about the possibility of this H1 strain reaching Asia and combining with the deadly H5 avian flu? Will this be Armageddon?
Dr Meirion Evans: Very unlikely.
Dr John McConnell: It might happen, but H5N1 has been around for at least 12 years in an environment where it could mix with other flu strains, and such a transmissible variety has not emerged. There is no more (nor less) likelihood now than there was before the emergence of Mexican swine H1N1 that a variant of H5N1 capable routine human to human transmission will emerge.
Dr. Steven McOrist: Given that this new human strain has not been isolated from pigs, it is misleading to suggest that the pig industry of Mexico has some specific role in the development of this new strain.
Mexican pig farms in my experience are clean and well-run with excellent staffing levels. Much of their pork has been exported to the Japanese market which has long demanded the very highest standards of cleanliness and care.
Is it also possible to contract swine flu through non-human contact such as through imported fruit and vegetables?
Dr Meirion Evans: No, not from pork either.
Dr John McConnell: No
How long can the virus "stay alive" on non-human surfaces?
Dr Meirion Evans: Around 24 hours on hard surfaces, shorter on clothing, bed linen etc. Use of disposable tissues rather than a handkerchief, and frequent hand washing will cut down the risk of picking it up in this way.
Dr John McConnell: Good question, don't know the answer
Prof Sally Bloomfield: It is thought that survival times vary on hard surfaces from one up to 24 hours depending on relative humidity temp etc. Survival on hand is thought to be much less.
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Your questions answered
Watch: the government's Chief Medical Officer Professor Sir Liam Donaldson joined Jon Snow to answers your questions about swine flu.
SYMPTOMS
What are the key symptoms we should look out for?
Dr Meirion Evans: High fever, headache, blocked nose, muscle aches, loss of appetite.
How do I know if my flu-like symptoms are "normal" flu vs. swine-flu?
Dr Meirion Evans: The symptoms are the same, but there is no normal flu circulating in the UK now as we have finished the normal flu season.
Dr John McConnell: Probably no way of telling.
Are there any important signifiers to suggest we may have swine flu rather than ordinary flu?
Dr Meirion Evans: The symptoms are the same. But if someone has recently returned from Mexico or is a contact of a confirmed case of swine flu, then it is much more likely that it could be swine flu.
What do I do if I get any flu symptoms?
Dr Adam Kamradt-Scott: Please call your doctor or NHS Direct immediately and advise them of your situation.
Dr Meirion Evans: Stay at home, restrict contact with household members e.g. stay in own room, and telephone NHS direct or your GP.
Dr John McConnell: Stay at home, call your GP or NHS Direct.
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RISK GROUPS
I returned from Mexico on 18 April with my wife and two young daughters only last Saturday (24th). We seem OK. But what is the incubation period?
Dr Adam Kamradt-Scott: The incubation period for influenza is usually between 1-4 days. If you returned to the UK five days ago now and are not exhibiting any symptoms already, you are likely to be fine. If symptoms do develop, please call your doctor or the NHS Direct immediately.
Dr Meirion Evans: Maximum seven days. Usually 1-4 days.
Dr John McConnell: Median incubation period is 1.4 days, maximum incubation period under four days. If not symptoms by now, you probably haven't brought it back from Mexico.
Are asthmatics or people with other respiratory conditions at any greater risk of contracting this flu?
Dr Adam Kamradt-Scott: Part of the problem with any influenza virus with pandemic potential is that everyone is at equal risk as they have little or no immunity to the new virus.
Dr Meirion Evans: No. They are not generally more at risk of catching it, but they are more at risk of having complications if they do get it.
Dr John McConnell: Not sure about greater risk of catching flu, but might have more serious illness.
Which age group is most at risk of fatalities? The old and very young or healthy young adults?
Dr Adam Kamradt-Scott: Usually in seasonal influenza only the elderly, very young, or people with compromised immune systems are at highest risk. We still do not know enough about this virus yet to see whether other population groups are also at risk.
Dr Meirion Evans: For seasonal flu it is young children and older people. For pandemic flu it varies - sometimes young healthy adults, sometimes older people. We don't know yet for this pandemic strain. In Mexico it appears to be younger adults, but bear in mind they have a relatively young population compared to UK.
Dr John McConnell: We don't know.
Is there any basis to think the young/old are more at risk to more at risk? Should they take extra precautions?
Dr Meirion Evans: We don't know at the moment. Older people may have some degree of immunity if they have been infected with a HI1N1 virus in the past.
Dr John McConnell: We don't know.
I commute to work by London underground every day. Am I at high risk from catching this virus from another passenger?
Dr John McConnell: Not at the moment because there's not yet evidence of sustained transmission in London
I would love to get an answer on whether or not the experts think that Mexican people may have some form of genetic disposition to being more seriously affected by this flu outbreak than others.
Dr Adam Kamradt-Scott: No. Influenza is a disease that can spread relatively easily amongst any population.
Dr John McConnell: So would I. Unlikely, but no evidence on which to base an answer.
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TREATMENTS AND VACCINES
Is there enough Tamiflu and vaccine for everyone?
Dr Adam Kamradt-Scott: The UK government yesterday announced that they are increasing their stockpile of Tamiflu to cover approximately 80 per cent of the UK population. There is no vaccine for this virus at the moment, and it will take at least six months before a vaccine will become available.
Dr Meirion Evans: No. In UK, around 30m doses of Tamiflu. This would be enough to deal with a 50 per cent attack rate of influenza which is the maximum anticipated attack rate under pandemic planning assumptions. There is no pandemic flu vaccine yet. Earliest availability will be 3-6 months and in the first instance it is likely one to be available in limited quantities.
Dr John McConnell: Enough Tamiflu for half the population, which should be enough. No vaccine and won't be one for several months.
Is there enough Tamiflu to go round? If not, is there an official policy on who gets it first?
Dr Meirion Evans: The official policy is that it will only be given to treat people with symptoms of flu. At present it is also being used to treat close contacts of confirmed flu cases. This is in order to try and slow down spread of flu and buy some more time for preparation. Once transmission is occurring within the UK, this use will stop.
Dr John McConnell: Enough for half the UK population. Official policy is to give it to people showing signs of illness. Supplies will quickly be exhausted if Tamiflu is used as a prophylactic, to prevent people being infected. Such a move would be foolish and ineffective, so preventive use is not official policy. See pandemic preparedness plan on Dept of Health website for details.
When would you estimate that a vaccine be available in my local doctor's surgery?
Dr Meirion Evans: Not for 3-6 months. The current vaccine does not protect against this new strain.
Dr John McConnell: October-November, if the decision is made to manufacture vaccine.
Should I buy my own Tamiflu on the internet or does the government have enough?
Dr John McConnell: Only if you have a prescription from your doctor, and you trust the online supplier not to sell you a counterfeit. Yes, it does
Medicines and Healthcare products Regulatory Agency (MHRA): the MHRA has expert assessment teams who will fast-track licence applications or variations to existing marketing authorisations which are in connection with emerging flu virus and which are necessary.
The MHRA advises the public not to buy Tamiflu, an anti-viral medicine, online. The government has already stockpiled anti-viral medicines to treat cases. Buying medicines online increases the risk of purchasing a product which may be of sub-standard, may not work or could be a fake/counterfeit.
Do developing countries have enough retrovirals to cope with a potential pandemic in say, Africa?
Dr Adam Kamradt-Scott: Some developing countries may have developed national stockpiles of antiviral medications, but the majority have not.
Dr John McConnell: Assume you mean antivirals, not retrovirals, of which most developing countries have little or no stockpiles, although WHO does have a limited stockpile (no where near enough) for emergency distribution.
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PREVENTION MEASURES
I have a three-month-old son. What can I do to protect him?
Dr Meirion Evans: Keep him away from anyone who has symptoms of flu. Flu is mainly spread by infected respiratory droplets when an infected person coughs or sneezes. This requires you to be within about one metre of the infected person. Covering mouth and nose when you cough/sneeze cuts down the risk.
Dr John McConnell: If the infection becomes widespread in the population, keep your son away people showing signs of illness. Guaranteeing protection may not be possible, but we haven't reached that stage yet.
Is it safe for me to travel with my wife and two young kids (aged one and three) to Texas next week (away for three weeks)?
Dr John McConnell: No official advice against travel to the USA at the moment, and I wouldn't advise otherwise.
At what point will the government ban travel to and from this country? That is surely the only way to deal with the cases we do have and prevent others getting in.
Dr Adam Kamradt-Scott: The UK government does not advocate border closures, and there is little point once the virus has entered the country from preventing people from entering.
Dr Meirion Evans: Unlikely - the genie is already out of the bottle. WHO phase five indicates that it is now spreading outside its country of origin. Travel restrictions are not an effective way to contain flu as once it has seeded in several places it is likely to begin spreading within-country quite soon.
Dr John McConnell:
It won't. Border closure would have to be an impossible, 99.9 per cent effective to make a difference to the speed of spread, and even then it wouldn't change the eventual magnitude of a national epidemic. On top of which, the economic disruption would be massive - e.g. what would we eat?
Would an immediate stop to people flying in and out of Mexico had had any effect in containing the virus?
Dr Adam Kamradt-Scott: There is the chance that ceasing all flights may have delayed the virus from spreading internationally so rapidly, but influenza is a disease that can be very easily spread.
Dr Meirion Evans: No, it's too late.
Dr John McConnell: Might have slowed it down a bit, but no meaningful effect. Stable door is open, horse (i.e. virus) has bolted.
Why don't we test people as they return from holiday in affected countries?
Dr Meirion Evans: A drain on resources and not an efficient way to control spread.
Dr John McConnell: We don't have sufficient laboratory capacity, and wouldn't have the results soon enough to make a difference.
Do face masks actually protect the wearer?
Dr Adam Kamradt-Scott: Face masks with a sufficiently high filtration level (N95 or P3), if fitted correctly, do provide protection to the wearer and are an effective preventative measure.
Dr Meirion Evans: Surgical face masks provide very little protection, if any, for contacts. If worn by the patient, they can cut down on the spread of respiratory droplets, but also need to be changed often to maintain this. Regular hand washing with soap or disinfectant gel is a more effective measure to protect yourself.
Dr John McConnell: Probably not. Their purpose is to prevent transmission, rather than acquisition, of infection
Dr Mark Fielder: Wearing face masks is currently only really relevant for healthcare workers or carers working with infected people directly. There is little use for the general public to use the masks currently.
The jury is essentially still out on face masks. Some claim they work well, but some claim they have a limited use. The Health Protection Agency suggests that healthcare professionals should wear surgical masks when dealing with infected patients. But we need to remember that surgical masks are not a replacement for hygiene practices, so good hand hygiene like washing hands is also important.
Surgical masks must be worn correctly and consistently during the time they are used. Improper use might allow contamination to take place and could possibly infect the wearer. Prior to putting a mask on the hands should be thoroughly washed with soap and water or use an alcohol-based hand sanitiser to reduce the chances of infection being spread.
If the mask is worn in the presence of infectious patients the mask may become contaminated so avoid touching the outer surface of the mask. The mask must then be immediately and appropriately disposed of. Once the mask has been removed and properly discarded hands should be thoroughly washed with soap and water, or use an alcohol-based hand sanitiser.
If there were to be a serious outbreak in the UK, how would Tamiflu be dished out?
Dr Meirion Evans: From local distribution centres. Someone will need to collect the tamiflu in behalf of the person who is ill.
Dr John McConnell: There is a policy: see pandemic preparedness plan on Dept of Health website for details.
I travel on the tube a lot and cannot always wash my hands with soap and water so would it be effective to carry and wash my hands with alcohol gel instead?
Dr Meirion Evans: Yes, this is a very good idea.
Dr John McConnell: Seems like a good idea, and don't touch your face while commuting.
Professor Lucy Yardley:
Yes, this is highly recommended. Handwashing as often as possible with soap or antibacterial hand gel is one of the methods of prevention for which the evidence is best.
Prof Sally Bloomfield:
Alcohol hand rubs are effective against the flu virus, as is the "first defence" foam product. We know that people tend to skip on hand washing when there is no soap and water around, so encouraging people to carry a hand rub is a good idea, especially for people who e.g. use public transport and public places a lot. Note that "antibacterials" are not necessarily also effective against viruses. Bleach is the most reliable disinfectant for killing viruses on hard surfaces such as door handles etc.
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PANDEMICS
What are the criteria by which this outbreak will become a true pandemic?
Dr Meirion Evans: Sustained spread in two or more countries.
What actually happens if it becomes classified as a pandemic - can we go to work? Travel? Commute?
Dr Meirion Evans: Yes, people will be encouraged to continue working.
Dr John McConnell: Yes, but best not to if you're feeling ill.
If the pandemic begins to take hold, will that be shut down in the same way football matches have been in Mexico?
Dr John McConnell: Not according to the government pandemic preparedness plan, but don't rule it out when politics overrules common sense.
How will we know when the danger is over?
Dr John McConnell: When the frequency of new cases drops below a determined level. Don't know what this level is.
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OTHER
Is there a good twitter account, RSS feed, or a site with email updates that I can use?
Dr John McConnell: I recommend this.
If the swine flu mutates with the avian flu, will we have flying-pig flu?
Dr John McConnell: Good question.
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Contributors
Thanks to the following for answering your questions:
- Dr Adam Kamradt-Scott, Research Fellow, Public and Environmental Health Research Unit, London School of Hygiene and Tropical Medicine
- Dr Meirion Evans, Senior Lecturer in Epidemiology and Public Health, Cardiff University
- Dr John McConnell, Editor of The Lancet Infectious Diseases
- Dr. Steven McOrist, UK Pig Veterinary Society, and Associate Professor & Reader of Veterinary Infectious Diseases, University of Nottingham
- Professor Lucy Yardley, School of Psychology, University of Southampton
- Prof Sally Bloomfield, Chair of the International Scientific Forum on Home Hygiene (IFH)
- Dr Mark Fielder, medical microbiology expert, Kingston University
Particular thanks to the Science Media Centre.
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