"We are not claiming victory because there are too many things to worry about. I won't be confident until March to say it's over for this winter because in the 1957/8 pandemic we saw a further peak after Christmas among older adults and with seasonal flu we often see a peak early in the New Year."

• The estimated number of cases of swine flu in England this week is 22,000 (range 11,000 to 47,000)

• The estimated cumulative number of cases in England is 790,000 (range 370,000 to 1,650,000) but given that one in five schoolchildren may well have had swine flu that estimate is probably several million out

• 747 people were in hospital in England at at 0800 on 2 December, of whom 161 were in intensive care

Deaths linked to H1N1 swine flu:
• England 178
• Wales 25
• Scotland 54
• Northern Ireland 13
• UK total 270

So bearing in mind that we may have had 5-10 million cases in the UK (a wild guess of my own I admit, based on school children etc), then 270 deaths is a very small proportion. That low death rate is no comfort of course to those who have lost family or who currently have relatives in hospital, but it is worth mentioning as this blog is there to inform and not to alarm.

Vaccination

The Head of Immunisation, Professor David Salisbury said that H1N1 swine flu had so completely replaced seasonal H1N1 flu that the WHO had already recommended that the pandemic strain replace it in next year's standard trivalent flu jab for the southern hemisphere, which is already under production. He predicted the same would apply in the northern hemisphere in 2010, although the WHO strain selection recommendation would not be made until February.

Professor Salisbury was also loathe to claim the worst was over:

"We have no way of knowing what will happen with seasonal flu early next year and what the pandemic virus might do, especially as immunity expands in the population, which may force the swine flu virus to drift. It makes us very cautious."

• 275,000 front-line health workers have been immunised in England - twice the number immunised the whole of last winter against seasonal flu. While that is a dramatic improvement, there are two million health workers on the target list, so there is a long way to go

• 1.6 million doses of vaccine have been given to the priority groups (up from 1 million last week)

• 11.2 million doses of GSK vaccine have been distributed throughout the UK to GPs, PCTs and hospitals

• 500,000 doses of Baxter vaccine have been distributed to health services

The hope must be that this will be resolved very quickly - I will investigate this further, although the department says the details of the contract negotiations are confidential.

A few graphs to end on:

Look at the red line - which is pretty static - and continues to be reassuring.

This shows that almost six out of 10 deaths are among the under-45s.

17% of deaths are among people who had been without any health conditions.
55% of deaths were among those with severe health problems.

I thought I'd show you this as it clearly displays that the second peak of flu in the United States is now on the wane. It's interesting that the US second wave was bigger than the first (the reverse of the UK). Likewise France is in the midst of a big peak of flu having had almost no first wave this summer.

More information on swine flu across the UK:

• Swine flu figures for England
• Swine flu figures in Northern Ireland
• Swine flu figures in Scotland
• Swine flu figures in Wales

PS. Many thanks to all of you who've sent get well wishes to my son and all the excellent suggestions for keeping him amused during his time off school with suspected swine flu. Hugo is now pretty much recovered and has started on his Christmas cards so is very busy (why do eight-year-olds have so many Christmas cards to send?).

Yesterday, a home swab kit arrived from the Health Protection Agency, so we'll know in a couple of weeks whether he really had H1N1 swine flu. My guess is yes, but I'll tell you whether I was right.

"There are examples of where flu viruses become less serious, as in the 1918 virus which became less lethal. There are also examples of flu viruses which become more pathogenic. It's not possible to second guess which way the drift will take us."

"With the 1918 pandemic, the way we estimated deaths was to look at the death data in several countries and then use modelling to work out how many were linked to flu. People do not count seasonal influenza deaths on a one by one basis, but with this current pandemic, there is so much interest, that we are counting cases. But it's too early to work out overall deaths and it will take one to two years to make the estimates. When we have those, then we will be in a much better position to see how this pandemic stacks up with seasonal flu and other pandemics."

Then I put in our postcode and was informed that my collection point was in Slough, but it was open only from 7-10pm every day. It was now 8am and I didn't want to wait 11 hours to get his antivirals. I rang our very good GP practice in Windsor and they referred me to Berkshire East Primary Care Trust, who in turn referred me to a national helpline. The national helpline suggested I go to Reading, or Wokingham.

In the end, we did get the Tamiflu in Reading, 15 miles away, and Hugo got his first dose by mid-morning. By contrast, Reading has 13 antiviral collection points and Wokingham has four. They are open throughout the day, and both have collection points open on Sundays. Why Slough and Windsor don't have at least one collection point open during normal hours completely mystifies me. Tyron Brown, the Project Manager for System Resilience at Berkshire East PCT told me that they "monitored volumes daily" and would expand the service if required.

Hugo is a very robust lad, but yesterday he was really quite poorly and refused food. But today is a different matter and he woke up and went straight to get his advent calendar (to eat the chocolate on 1 December). He still has a hacking cough but is definitely on the mend. Any suggestions as to how I keep him amused for the next couple of days would be gratefully received.

Update 1358: The Director for Public Health for East Berkshire, Dr Pat Riordan, has called me to say that, in the light of my post, she is going to improve access to antivirals for the residents of Slough and Windsor.

A new daytime antiviral collection point is to be set up somewhere in the locality. As Dr Riordan put it to me: "I do listen to all suggestions and comments. It's not appropriate to have people hanging around half a day for their Tamiflu. We want to provide an effective and efficient service."

But I would like to draw your attention to a couple of issues which many of you are likely to pick up elsewhere on the web or perhaps in the papers.

The first is a big jump in the global death toll. The World Health Organization said the number of deaths was up around 1,000 on a week ago, reaching at least 7,826 worldwide since the H1N1 virus emerged in April. That should neither surprise nor alarm you. We are now getting into the peak flu season. Seasonal flu kills several hundred thousand very elderly and frail people each year. The difference with swine flu is that the majority of deaths are in the under-65s.

On a more positive note, the WHO said that the epidemic may have peaked in parts of the northern hemisphere. That seems to be the case in the UK and in the United States, which has had several weeks of falling levels of flu.

Secondly, I have picked up via BBC Monitoring that two patients in France, in different hospitals, have died from mutated H1N1 swine flu. (For those who don't know, the BBC monitoring service is based in Caversham in Reading; it listens to news broadcasts from around the world and provides accurate translations.)

The monitoring translation of La Chaine Info Television went like this:

French newsreader: "The health authorities dreaded this. The H1N1 virus is in the process of mutating. The phenomenon reported in Norway has also been detected in France in two deceased patients who were not related in any way and who were in hospitals in two different cities. This mutation could increase the virus's ability to affect certain airways, as well as the lungs."

Read like that, it seems pretty scary, and it is certainly not good news that mutations are occurring. But, as has been pointed out by me and by many of the wise men and women who post comments here, mutations are what we should expect with flu. Flu is an RNA virus in which genetic replication is pretty poor and which makes lots of mistakes. It's the reason that flu viruses drift and the reason we need a new flu jab every winter.

The mutations reported in France have been seen in Norway and in several other countries, and the WHO put out some very clear advice on this recently.

The French mutation has been found in two cities, but we need to know a lot more about it before becoming unduly alarmed. The patients may have been immuno-compromised, making them more susceptible to mutated viruses, and we don't have any evidence that mutated strains are spreading in the wider community.

To sum up, mutation and deaths are sadly unavoidable when it comes to H1N1 swine flu. But this pandemic is still reassuringly mild for the vast vast majority of those infected.

Across the UK, 10 million doses of the vaccine have been distributed to GPs and hospitals.

That one million figure refers to those in the initial priority groups, such as those with chronic asthma, heart and other organ disease, immune problems and pregnant women.

Clearly there is still a long way to go. There are nine million people in the priority groups in England, and around 11.5 million across the UK. Then add to that the three million or more under fives who will be offered the jab after that.

Professor David Salisbury, Director of Immunisation at the Department of Health said he hoped GPs would now be able to accelerate the vaccination process:

"All GPs have now had some vaccine and we are now at the stage of re-stocking them and so the brakes can come off to some extent. We'd like to get the priority groups vaccinated before Christmas, and there will be enough vaccine to do that. GPs don't want to call in patients if they are unsure there have enough vaccine, but now they know they have it in the fridge they can go full throttle."

Professor Salisbury said he wanted doctors to get through the priority groups as quickly as possible so that they could move on to immunising children under five.

Carers for the elderly and disabled will also be entitled to receive the swine flu jab once the initial priority groups have been cleared.

I hope this answers some of the questions many of you have raised about the roll-out of the vaccine.

There are no figures yet for the uptake of vaccine among more than two million front-line health workers.

But Ian Dalton, National Director for Flu Resilience said that "informal conversations" had shown promising levels of uptake. He gave some examples:

• West Midlands Ambulance Service has offered the jab to around 1,000 front line staff and 70% have accepted.
• Guy's and St Thomas' Hospitals have received 2,000 doses and used 1,500 already.
• They have also immunised 4,000 staff against seasonal flu, double the number last year.

So how much swine flu is there in Britain at present? Estimated figures from across the UK suggest cases are falling very slightly but the number of deaths is rising sharply.

Indeed the past week has seen the biggest single rise in deaths since the pandemic began.

UK deaths to date related to H1N1 swine flu: 245
163 England
13 Northern Ireland
46 Scotland
23 Wales

Why are deaths rising if cases are falling? Firstly, remember that weekly estimates for the number of cases of swine flu are probably wildly out (but are useful for showing trends over time).

The latest weekly estimate for England was 46,000 cases of swine flu with a cumulative total of 760,000. But since the Health Protection Agency now reckons that one in five children may have had swine flu, that cumulative figure maybe just a tenth of the real total (and that's just my guess).

I've discussed this apparent contradiction about falling cases and rising death rates earlier this month - something that has been seen in other countries.

It's important to note that there is no evidence that the H1N1 swine flu virus is mutating into something more deadly.

Finally a few graphs - very useful for showing trends. My thanks to the Department of Health and the RCGP for supplying the data:

You can see that the rate of flu is now about average for this time of year but well below the peak we saw in July.

This is a snapshot of the number of patients in hospital in England with suspected swine flu related illness as of 25 November. It's always worth showing this because it's a reminder that while flu is mild for most, for a small minority it can be very serious.

This is the first time I've seen this. It reveals the death toll from swine flu, in England from week to week. You can see that the rate has risen throughout November.

Useful resources:

• Detailed UK weekly epidemiology update
• Swine flu figures for Northern Ireland
• Swine flu figures for Scotland
• Swine flu figures for Wales

Knowing that would be incredibly useful, as the bigger the proportion infected, the further we are into this pandemic and the less likely there will be a further sting in its tail.

The Health Protection Agency (HPA) has done blood tests of hundreds of children and parents connected to early school outbreaks.

With one school in south west England they tested around 500 people. They found that although around one in 10 children fell ill, three to five times as many got infected and developed antibodies.

After analysing this and other data relating to the number of children being seen by GPs, the HPA has now come up with these interesting estimates:

• Up to one third of children in swine flu hotspots (such as England and the West Midlands) have already been infected with the H1N1 virus.
• Across the UK up to one in five children has had had swine flu.
• About half of those who get infected show no symptoms.

This is all very reassuring. Professor Maria Zambon from the HPA said:

"We didn't get the pandemic that we planned for and you might say that we've been lobbed a soft ball. There hasn't been high case mortality, the virus is sensitive to drugs, and we've been able to make vaccine and roll it out. I am incredibly grateful that we are not dealing with a pandemic of H5 (bird flu)."

Professor Zambon said the virus had had a relatively low impact on older adults and that was probably explained by pre-existing immunity. The HPA has these estimates:

• For those aged over 50 up to four in 10 people have pre-existing protective antibodies to the H1N1 pandemic virus.
• If you are under 50 it falls to around one in 10 of the population.

The professor, who is an acknowledged world expert on flu, did utter a few words of caution. "Influenza is full of mystery and intrigue. It has lots of twists and turns" and she predicted that mutations of the swine flu virus should be expected. She also pointed out that there could still be a substantial outbreak of seasonal flu over winter.

Now Canadian health officials and the manufacturers GlaxoSmithKline have asked doctors to stop using a single batch of 172,000 doses.

It comes after six people apparently experienced severe allergic reactions - which might include breathing problems, raised heart rate and skin rashes.

GSK is investigating the reports - this may result in the withdrawal of the batch. It's reported that one in 20,000 people suffered reactions to this batch - five times the expected number.

None suffered long term ill effects. The vaccination programme in Canada is continuing, using other supplies of Pandemrix.

A spokeswoman for GSK Gwenan White said that 7.5 million doses of Pandemrix had been distributed in Canada and the action taken over the batch was a purely precautionary measure. "It may well be that after further investigation, the batch can be used" she said.

Canada's doses are produced at a manufacturing plant in Quebec. None of the stocks of vaccine bound for the UK are affected - all produced at a plant in Dresden, Germany.

Only yesterday GSK announced that more than 40 million doses of Pandemrix had been distributed globally - something it revealed first in this blog a week ago.

GSK also announced results from a clinical trial among children which showed a strong immune response from one dose of Pandemrix.

Update, 08:58, Wednesday 25 November: I've received this statement from Geoffrey Matthews at the Public Health Agency of Canada about Arepanrix which is the Canadian name for Pandemrix:

"The Public Health Agency of Canada, is reviewing reports of a higher than normal number of adverse events associated with one particular lot of the H1N1 flu vaccine that was distributed over the week of November 2, 2009.

"As a precautionary step, on November 18 Health Canada asked GSK to instruct provinces who have received adjuvanted GSK vaccine Arepanrix doses from Lot 7A ( BC, AB, SK, NB, ON, PEI) not to use any remaining doses of that lot for vaccination.

"This will allow Health Canada, GSK, the Public Health Agency of Canada and the relevant jurisdictions to investigate the cause of the higher than expected number of allergic reactions to the vaccine in persons immunized with that Lot.

"Placing vaccine lots on hold is not an unusual occurrence. Over the past few years, Health Canada has placed specific lots of other vaccine on hold pending further investigation.

"A total of six adverse events (all analyphlaxis) associated with this lot have been reported (the lot in question comprises 172,000 doses). All six individuals who experienced severe allergic reactions have fully recovered.

"Anaphylaxis is a severe allergic reaction that is readily treatable, but can be life-threatening. Therefore it is considered a serious adverse event.

"The Public Health Agency of Canada, Health Canada (the regulator) and the provinces and territories have been working together, and with Canada's vaccine manufacturer, to ensure that all adverse events are reported and assessed.

"People who have received the vaccine and have not had an allergic reaction, have no reason to be concerned.

"The H1N1 flu virus vaccine has proven to be both safe and highly effective. The fact that we have identified a potential safety issue underscores that our monitoring system works."

He gave some more detail about the patients: "Of the five, two have recovered and been discharged having recovered. Of the three in hospital, one is in critical care and two are on the wards but being isolated from other patients."

So how important is this? Hopefully this will be a viral dead-end and it won't go any further. I'm told all the patients were immunocompromised and so especially vulnerable to developing Tamiflu resistance.

Dr Roland Salmon, director of the NPHS Communicable Disease Surveillance Centre, said:

"The emergence of influenza A viruses that are resistant to Tamiflu is not unexpected in patients with serious underlying conditions and suppressed immune systems, who still test positive for the virus despite treatment."

Finally, just to stress, there's no evidence or suggestion that a "new" Tamiflu-resistant strain of H1N1 virus is now "out there" in the community. But public health officials in Wales will be very busy this weekend tracing contacts to ensure they have contained this among this small group of patients.

Health officials in Cardiff are investigating the spread of a Tamiflu-resistant strain of swine flu at University Hospital Wales. The strain has infected a small number of patients, all of whom have serious underlying health conditions.

Roche, the maker of Tamiflu, tells me that there have been 57 cases worldwide of people developing resistance to Tamiflu while taking the drug (seven of these in the UK).

But what happened at University Hospital Wales may be quite different. Here, someone developed resistance - and then, I understand, this strain appears to have been passed from person to person in the hospital.

There's been only one other similar case in the United States between two people at a summer camp, but the resistant strain did not spread any further. The CDC reported on this in September.

Health officials in Wales tell me that more tests are being carried out to confirm exactly what happened, and they are not yet confirming person-to-person spread.

All the patients are said to be recovering and being cared for in controlled environments, so there is no risk to anyone else.

Tamiflu is an antiviral and can reduce the risk of the complications of flu, as well as shortening the duration of the illness. The UK has enough doses for half the population. Any spread of a Tamiflu-resistant strain of swine flu would be a serious public health concern - but there is no evidence to suggest that this has happened.

Obviously this is a developing story, and I'll bring you more when I get it.

It will be offered to all children aged between six months and five years of age. That's around three million children in the UK.

They'll have two jabs, three weeks apart. One dose of vaccine appears to give good immunity, and it's possible that the European regulators may amend their recommendation to one jab at some point.

The Department of Health has released details of a Mori poll - 73% of parents asked said they'd give the vaccine to their children. We filmed at a playgroup in Birmingham - the city with the highest rate of swine flu in England - and most parents were very positive.

Obviously all parents will have to make personal decisions about whether to have their children immunised - the clear recommendation from vaccine experts, paediatricians and public health officials is that the vaccine is safe, with few apparent side-effects, and that it's the best (and the only way) to protect children.

Plenty of commenters here have said they are going to have or had had the jab. Plenty have expressed concerns, among them quite a few pregnant women. But what percentage of the 11 million people in at-risk groups are going to have the jab?

Professor Steve Field of the Royal College of GPs said it was far too early to work out uptake figures. He pointed out that some GP surgeries had got their first doses only last week. Clearly you can't have a jab (or turn it down) until you are offered it.

Which brings us to surveys, polls and rune reading (okay, not the last).

A "snapshot survey" of 107 GPs in England for Pulse, a magazine for health professionals, indicated that only of patients offered the jab, only 46% accepted.

This was widely reported, but it worries me that this is a self-selecting group. And 107 GPs out of 37,213 in England is not a representative sample.

An GfK-NOP telephone poll for the BBC of just over 2,000 people in the UK asked the following questions about swine flu.

If you were offered the swine flu vaccine would you be happy to have it?
• Yes 52%
• No 27%
• Don't know 21%
 
If you said "No" or "Don't know" to the above question, which of the following factors would influence your decision?
• Don't think it's needed 36%
• Don't think it will work 11%
• I'm concerned about safety 43%
• Don't know what the vaccine would do 35%
 
NHS staff are being offered the vaccine to protect themselves and also to help protect patients they are looking after who may be more vulnerable to flu. Do you think they should agree to have it?
• Yes 70%
• No 10%
• Don't know 20%

Some interesting answers there, but remember: this was a sample of the UK population, not a sample of people in the at-risk groups.

You would think that if 2,000 people with asthma, diabetes and immune disorders were polled, the percentage willing to have the vaccine would be higher. So it tells us a bit, but not that much.

So finally I resorted to a single GP practice. Dr Dean Marshall is a GP in Edinburgh, but he is also chairman of the BMA Scottish GPs committee. How is immunisation against swine flu going at his practice?

"It's very early days, but so far we've not been getting a fantastic response from pregnant women. Because they are at greatly increased risk of complications from swine flu, we have been ringing them up to offer the vaccine and about half have said yes, but the rest declined or are still thinking about it.
 
Overall, we've immunised about 300 people in the at-risk groups. You always get some reluctance with any new vaccine and we've not had long to get a public education campaign going with swine flu. We are clearly going to have to work hard to convince many people to have the jab."

Many people have questions about the vaccine and wonder whether they should have it. On that there is very clear advice from all medical bodies and public health experts: if you are in an at-risk group (such as those with asthma, heart disease, lung problems, immune disorders or are pregnant), you really should have the vaccine.

But what of the manufacturers of Britain's preferred swine flu vaccine? I thought it would be a good idea to put some questions to GSK, which researched, developed and produces Pandemrix.

Dr Thomas Breuer is based at GSK's massive vaccine plant at Rixensart in Belgium. His full title is Senior Vice President Global Clinical R&D and Chief Medical Officer - which means he is the person to quiz about the vaccine.

So here are ten questions about the swine flu vaccine.

"Pandemrix has been licensed for use by European regulators following a thorough review of manufacturing quality, the immunity it induces and its safety profile. This was based on information from clinical trials of GSK's H5N1 (bird flu) pandemic vaccine, which has been studied over several years and in more than 12,000 patients.
 
"In addition, more than 3,000 people have now been vaccinated with Pandemrix as part of the ongoing clinical trials programme."

Preliminary data from the initial H1N1 clinical trials are already available at the Clinical Study Registry.

2) What about mass immunisation campaigns?

"So far, 22 countries have announced vaccination programmes; of these, more than half are using the GSK vaccine, Pandemrix. Supply commenced during October and more then 40 million doses will be supplied to governments within this first month."

3) Pandemrix contains and adjuvant, AS03. What is it and what does it do?

"An adjuvant is added to the vaccine and increases the immune response to vaccination ("adjuvant" comes from the Latin word "adjuvans", meaning "to help"). At GSK, we've been developing adjuvant technology for almost 20 years.
 
"AS03 is an oil-in-water, emulsion-based adjuvant, which contains vitamin E, polysorbate (a widely used component of medicinal products) and squalene, an oil.
 
"Squalene is part of a human's natural metabolism. We need it to synthesize cholesterol and some hormones. It is ubiquitous - it is found in animals and in a variety of foods, cosmetics, over-the-counter drugs and health supplements.
 
"AS03 has been used in a number of candidate vaccines and tested in more than 41,000 people in various influenza vaccine clinical trials."

4) Why did you decide to create an adjuvanted pandemic flu vaccine when there is much more experience of unadjuvanted flu shots?

"The antigen is the component of the vaccine that elicits the immune response. One of the major benefits of adjuvants is that they allow less antigen to be used per dose of vaccine (for the same or even better immune response) and therefore increase the number of doses available.
 
"When flu viruses drift, vaccines can often become less effective. An adjuvanted vaccine can produce a good immune response to viruses that are similar, but not exactly the same as the vaccine target.
 
"GSK has demonstrated cross-protection in clinical trials for the adjuvanted H5N1 vaccine and expect to show this feature again in our ongoing H1N1 Pandemrix trials once a drift of the flu strain is observed."

5) What are the common side-effects from Pandemrix and have your trials or the mass immunisation campaigns noted any serious adverse events?

"Several thousand people have now received Pandemrix in our clinical trials, while 10 million people have now been vaccinated as part of ongoing government-led vaccination campaigns.
 
"All vaccines can cause side-effects in some people. Data available from the clinical trials has shown that both Pandemrix and our adjuvanted H5N1 vaccine are generally well tolerated with a safety profile that you would expect from such a vaccine. In other words, these side effects were in line with, or slightly more frequent than has been seen with GSK's current unadjuvanted seasonal influenza vaccines.
 
"The most frequently reported reactions for Pandemrix are injection site reactions (including pain, swelling, local numbness and bruising) and symptoms that are common effects of many vaccines, such as dizziness, headache, fatigue, muscle aches, malaise, mild fever, swollen or enlarged lymph nodes, nausea and vomiting.
 
"More serious adverse reactions that are very rarely seen can occur. However, public health agencies as well as GSK always have to investigate whether such events are causally associated with vaccination or occur just by chance in timely association with vaccination. Vaccinating millions of people in a very short timeframe will generate many situations where events will be reported in coincidental timely association.
 
"As the antigen of Pandemrix is produced in eggs, it is contraindicated for people with a history of anaphylactic reactions to eggs. To date, anaphylactioid reactions with Pandemrix have been reported very rarely and these cases were managed in the appropriate way by the healthcare practitioners involved. In addition, the number of cases reported is not in excess of what would be expected. So far no confirmed cases of Guillain-Barre syndrome have been reported."

Monitoring adverse events:

• MHRA weekly update
• Yellow Card Scheme
• The Medical Products Agency in Sweden

6) What testing has been done which relates to the safety of Pandemrix during pregnancy?

"GSK has performed preclinical tests. These tests do not indicate reproductive toxicity. Pandemrix has not been formally studied in pregnant women as part of a clinical trial program.
 
"We know that thousands of pregnant women have already been vaccinated with Pandemrix as part of the government-led immunisation programmes. GSK is actively working with governments to follow these women long term."

7) There is very clear evidence that pregnant women are at increased risk from H1N1 swine flu compared with the general population. Despite that, a lot of pregnant women are agonising over the decision of whether to be immunised. While your vaccine is being offered to pregnant women here, the Swiss authorities have decided that they will use an unadjuvanted vaccine for pregnant women. What's your view?

"The Swiss, just like each and every regulatory agency, have to look at the data and make their decision. We have data from animal studies and from other research. From a theoretical point of view, we have studied our adjuvants carefully and don't believe there is a risk - but we don't have clinical data specifically in pregnant women.
 
"But we are not promoting the vaccine for any particular group. We give the data and leave it up to regulators. France has decided to give unadjuvanted vaccines to pregnant women. In Canada, the government has decided to use our vaccine for pregnant women, as has the UK.
 
"Each mother and each doctor has to weigh up the known risks of getting H1N1 and the theoretical risk of having the vaccine and make a personal decision. It's worth pointing out that pregnant women have been immunised with seasonal flu vaccines for years."

8) Where is the vaccine made and how many doses of Pandemrix are coming off the production line each week?

"GSK has two manufacturing sites, based in Dresden in Germany and Quebec in Canada. We will be supplying a total of more than 440 million doses to more than 40 governments with H1N1 vaccine produced by these two sites.
 
"The development, manufacture and shipping process is complex and a tightly-controlled process. In addition to vaccine production, it's also important to make sure all vaccine doses meet the stringent quality control standards and regulatory requirements before being shipped.
 
"As a result of the complex process involved, production varies from week to week. As of the end of October, GSK has shipped more than 40 million doses and in the weeks ahead we'll be supplying tens of millions of doses of vaccine to countries all over the world.
 
"To date, 6.4 million doses have been sent to the UK. GSK continues to make every effort to supply the maximum supply possible from its manufacturing sites."

9) Will you be making doses available privately and what will the likely cost be?

"No. We are committed making Pandemrix available to governments to support efforts to protect their people. Some governments may decide to use the private sector to distribute their doses.
 
"We have also allocated 20% of production at our Quebec site to supporting developing countries. This includes a donation of 50 million doses to the World Health Organization. At GSK, there is no preferential treatment for staff."

10) Can you understand that some people feel instinctively suspicious of big pharma and its motives? GSK posted quarterly profits of £1.44bn last month. How would you and GSK respond to the charge that profits are more the driving force rather than patients, and that the pandemic is perhaps seen as a good source of income for the company?

"Companies like GSK have to take significant financial risks upfront to be ready to provide a solution and invest a significant part of their profits in development of future vaccines. We have already spent £2bn in developing technologies to respond to an influenza pandemic and increasing capacity at our vaccine and antiviral manufacturing sites.
 
"We are trying to strike a balance between the expectations of society and our shareholders, who justifiably want to see a return on the risks we take. The only entities currently providing solutions to fight the pandemic are publicly-traded companies. And on a personal note, making a difference in public health is what makes me tick and what gets me out of bed into work every day."

Update 1510: Some readers have asked for more detail in Question 8; I have altered the post above to quote Dr Breuer's answer in full.

So it is timely that the Department of Health is issuing a new leaflet for pregnant women. It should be available in GP surgeries from next week, but you can read it online now.

We don't yet know what the uptake of the vaccine has been among pregnant women.

The Chief Medical Officer for England, Sir Liam Donaldson, recognises that many women will be agonising over what to do:

"It's obvious that pregnant women worry about catching flu and having a vaccine... it is a difficult time for them and a difficult decision. It is their choice, but the information we have given out will help people to take that decision. The best way for them to protect themselves and their baby is to have the vaccine."

Vaccine distribution

Have you had your swine flu jab yet? The Department of Health says that 6.6 million doses of Pandemrix have been distributed so far and that, by the end of this week, "virtually all GPs" will have received their first delivery of vaccine. Officials say the campaign is "on track".

Healthy children next?

I have said several times that an announcement extending immunisation to all children is inevitable.

The Department of Health continues to insist that no decision has been made and it won't confirm that healthy children will be the next group. A decision is expected within two weeks.

But rather like the plot of a thriller where you guess the ending long before you get to it, it is abundantly clear that children will be the next in line for the jab, once at-risk groups have been immunised.

There is no rush to make an announcement, as there are millions of people with asthma, heart disease and other conditions to immunise before children can be targeted.

Cases down but deaths up

Meanwhile, the H1N1 virus continues its unpredictable course. The number of cases is falling in much of the UK, but there has been a significant increase in the number of deaths.

There were an estimated 64,000 new cases of swine flu in England in the past week, a fall of 20,000.

There were decreases in Northern Ireland and cases seem to have stalled in Wales (on one measure in Wales cases rose, and on another they fell).

Only Scotland showed an definite increase. Health officials think the dip in cases may be due to the recent half-term school holidays.

At the same time, there has been a big jump in the number of deaths, up by 28 to 182 across the UK.

But there is no evidence that the virus is becoming more virulent. Sir Liam Donaldson said:

"[T]he lab scientists continue to watch the virus and it's not changing, but it looks like now the virus is out of the summer it has a more serious spectrum about it."

You can see that the red line is showing a bit of a dip. This is good news, as it gives GPs a breathing space to get people immunised.

It's reckoned that 620,000 people in England have now had swine flu - but that is a very rough estimate and the true total may be much higher.

The vast majority have had a mild illness, but of concern is the small minority who need hospital treatment.

This demonstrates the ugly side of swine flu. As of 0800 on Wednesday, there were 785 people in hospital in England with swine-flu-related illness, 173 of those in intensive care. There were 109 people in hospital in Scotland.

The overall number of deaths linked to swine flu now stands at 154 for the UK: 105 in England; 31 in Scotland; eight in Wales and 10 in Northern Ireland.

That represents a rise of 28 deaths from the previous week. The average age of those who have died is 44.

I've included this data because it illustrates the difference between pandemic and seasonal flu. You can see that, whereas those over the age of 60 make up the peak group hospitalised by seasonal flu, it is children who are most affected by swine flu.

This graph shows that whereas 94% of deaths from seasonal flu are in the 65+ age group, with swine flu the fatalities are much more evenly spread.

Indeed, 60% of the deaths so far have been of people under the age of 45. 20% of those who have died had no underlying health conditions.

Useful resources

• Health Protection Agency data for the UK
• Swine flu figures for England
• Swine flu figures for Northern Ireland
• Swine flu figures for Scotland
• Swine flu figures for Wales

This applies especially to H1N1 swine flu which, admittedly, has only been circulating in humans for a matter of months.

A series of research projects in the UK have been announced which will examine every aspect of the swine flu virus - in pig and human populations, and in hospital intensive care units.

£7.5 million pounds of funding has been given by the Medical Research Council (MRC), Wellcome Trust, and Biotechnology and Biological Sciences Research Council (BBSRC) along with some government support.

The research will aim to answer many of the questions which commenters on this blog have raised, and more besides:

• Why do some people and not others become seriously ill with swine flu?
• What proportion of people who are infected have no symptoms (what's known as asymptomatic)?
• If you are asymptomatic, can you still spread flu?
• How useful are antivirals?
• How effective is the vaccine?
• How does H1N1 swine flu behave in pigs?
• Is there a risk that the virus could evolve into a more virulent form in pigs?
• Is there a need for a vaccine for pigs to slow the spread of the virus?

Fluwatch

A study led by Dr Andrew Hayward of University College London, which will follow up to 10,000 people and look at the duration and severity of symptoms, their access to treatment, use of antivirals and uptake of the vaccine.

We should not have to wait long for results. Dr Hayward said he hoped to release initial data before Christmas.

This study should help scientists work out what proportion of the population has had swine flu. This is crucial because at present we have only tenuous estimates from the Health Protection Agency which are subject to a huge margin of error.

Last week's estimated cumulative number of cases was 620,000 in England (with a range from 289,000 to 1,278,000).

The reason we don't have a clear idea of how many people are infected is because the majority of those who get flu, never go anywhere near the health service and only the sickest patients get tested for the virus.

If we knew what proportion had no symptoms or recovered without bothering their doctor, it would help us understand how quickly we may get through this pandemic.

It will also look at how effective antivirals have been in treating flu - a hot topic for months. Some have criticised the policy here of offering Tamiflu to anyone who says they have flu-like symptoms.

Dr Fred Hayden from the Wellcome Trust (Professor of Medicine at the University of Virginia) pointed to a study in the New England Journal of Medicine last month. This looked at nearly 300 patients admitted to hospital in the United States.

Dr Hayden said:

"[F]or those admitted to hospital, the average time they waited before getting antivirals was three days, for those admitted to intensive care it was six days and for those who died it was eight days."

He said that early treatment, even in uncomplicated seasonal flu, could reduce the risk of complications.

The Mechanisms of Severe Acute Influenza Consortium (MOSAIC)

Thankfully the principal investigator, Professor Peter Openshaw from Imperial College London, came up with the snappy acronym MOSAIC.

A team of scientists from England and Scotland will look at up to 500 people hospitalised with flu during the pandemic and try to find out what factors contributed to the severity of their disease.

For example, was there something about their genetic make-up which made them more susceptible to the virus, or was it due to variations in the virus itself?

They'll be taking around 40 samples from each volunteer and doing extensive virology and bacterial work in several UK labs.

This study will take about a year to complete and, like the others, could yield useful information for future pandemics.

Combating Swine Influenza (COSI) Initiative

There are two studies here looking at the evolution and spread of pandemic H1N1 virus in pigs and how to develop ways to slow the spread of the virus in animals and humans.

The research will be led by Professor James Wood at the University of Cambridge and Professor Ian Brown at the Veterinary Laboratories agency at Weybridge.

Professor Wood said that for the last 10 years scientists had concentrated more on avian influenza and there was a lack of detailed surveillance in pigs.

"It's important we understand the evolution of the H1N1 pandemic" he said. "We need to look at where it came from and how it's evolving. It's possible that it may take a different evolutionary course in pigs and pose a different threat to humans."

He pointed out that farmers had passed the H1N1 pandemic virus to pigs in Argentina, Australia, the USA and Canada.

One issue that has been puzzling me is why the pandemic virus is currently so stable. We are always told that RNA viruses like flu have a high mutation rate. It's why people need a flu jab each autumn.

Professor Wendy Barclay, virologist at Imperial College London said there was genuine uncertainty about the H1N1 swine flu virus: "We don't know why it's so stable" she said.

Nonetheless, she had a theory:

"It currently has a huge number of hosts (people) to infect and so has no pressure to mutate. But as more people develop immunity it will have to work a lot harder and so we will expect to see drift (mutations) which might be accompanied by changes in its virulence."

That might of course mean that swine flu has a sting in its tail. "Pandemic, what pandemic?" has been the refrain from some journalistic colleagues recently. And it's true that the first pandemic of the 21st Century is a viral pushover for the vast majority of us.

But for a small minority it is a serious threat, hospitalising hundreds of Britons each week, a good proportion of whom have no underlying health problems.

The sooner we know why flu is able to breech the defences of some people and not others, the sooner we might be able to develop better ways to beat the virus.

New figures from the World Health Organization show the virus has now spread to more than 199 countries and territories and that there have been more than 6,000 deaths.

Although every death is a tragedy, that is a remarkably small number given that seasonal flu is reckoned to contribute to the deaths of at least 250,000 people per year. It is yet further evidence of the generally mild nature of the virus.

Having said that, swine flu has a sting in its tail.

Australia, like several other southern hemisphere countries, has recently emerged from its winter flu season.

Deaths were low compared to seasonal flu, but hospital intensive care units had not seen anything like it in 40 years; indeed, since the pandemic of 1968-70.

It sums up the apparent contradiction about this pandemic: mild for most, but very serious for a small minority.

Those at greatest risk of complications are pregnant women and anyone with an existing health condition such as asthma. That's why these groups are being immunised first.

Unlike seasonal flu, which tends to kill the frail elderly, the average age of those who've died from the virus here in the UK is 44. One in five of those who have died had no previous health problems.

As I have said before, swine flu should not be a reason to panic - nor is it something to dismiss out of hand. We can all do our bit to minimise the spread of the virus by following good respiratory and hand hygiene.

Several of you have asked about what's happening in Ukraine which, in just a few weeks, has recorded more than 250,000 cases of flu-like illness, with 235 people needing intensive care and 70 deaths.

As far as I can make out, there does not seem to be anything unusual about the outbreak there. One health official said it was probably a reflection of the poor state of the health service that the virus had had such an intense effect.

Crucially, samples of the virus have shown that it is not mutating, so is the same H1N1 pandemic strain that is circulating worldwide. As long as that remains the case, we should feel reassured.

Finally, if the virus has spread to 199 countries and territories, does anyone know where on the planet has not experienced swine flu?