The swine flu paradox
The latest figures on H1N1 swine flu may get scant publicity, but they are worth investigating as they reveal an apparent contradiction which will become hugely important in the coming months.
The paradox is this: swine flu is a mild illness, yet intensive care units are under mounting pressure.
How to explain this? It is true, and worth repeating, that the vast majority of us who get swine flu will not be seriously ill.
Many will have extremely mild symptoms; others will feel lousy for a few days and be confined to bed, which still counts as a mild illness.
Rest and plenty of fluids will be all they require. Antivirals may help to reduce symptoms.
But a minority will get complications. While most of those will have underlying health problems (like asthma or heart disease), not all will - so it is impossible to predict who will be unlucky enough to need hospital treatment as a result of the virus.
Statistics released by the chief medical officer for England, Sir Liam Donaldson help illustrate the swine flu paradox.
This table shows that there were 751 patients in hospital in England with swine-flu-related illness as of yesterday, of whom 157 were in critical care. That means 20% of hospitalised swine flu patients require critical care.
That is both the highest number in intensive care since the outbreak began and the highest proportion of hospitalised patients. It means one in five people hospitalised with swine flu now require intensive care.
Sir Liam Donaldson said there was "an eerie similarity" with what happened in Australia during its recent winter, where 25% of hospital admissions for swine flu ended up in intensive care.
Another graph further illustrates the problem of predicting who will be struck down by swine flu.
This is a study of nearly 400 patients admitted to hospital in England with swine flu. Those who had existing health problems are coloured blue; those without are burgundy.
You can see that only 19% of the under-5s have existing conditions (the jargon term is comorbidity). Only 42% of those aged 5-15 who need hospital treatment have other health problems.
These figures should not alarm you. Remember that most people will get a mild illness (if I had a pound for every time I wrote that...).
It is simply worth pointing out that just because you are a healthy person with healthy children, it does not mean that swine flu cannot turn your life upside down.
On a positive note, most of those who end up in critical care will recover completely. But having seen patients on life support because of H1N1, I can assure you this is not a virus to dismiss out of hand.
Young children under five make up the group most likely to require hospital treatment and those most likely to have been entirely healthy before.
It's for this reason that it seems inevitable to me that the Department of Health will eventually offer swine flu immunisation to all children.
This will come after a recommendation from the JCVI (The Joint Committee on Vaccination and Immunisation). The United States is offering immunisation for everyone aged six months to 24 years, in addition to at-risk groups.
Sir Liam Donaldson confirmed today they would eventually extend the immunisation programme beyond at-risk groups and health workers. He said: "It will be expanded. It's just how we do it."
Expect an announcement expanding the programme to all infants and school age children before Christmas.
My hunch would be that the decision has probably already been made, but that health officials want to focus on getting the first wave of immunisation well under way before making any announcement.
Ian Dalton, national director for flu resilience, said all GPs in England should get their first box of 500 doses of H1N1 vaccine in the next three to four weeks.
That means many of those who have serious health conditions are likely to be waiting well into December for their jab.
Some, though, are getting letters (post strike permitting) inviting them to get a swine flu shot and may be wondering whether to have the jab. It's a personal choice. What people must ask themselves is why they wouldn't have it.
Is it because they think the virus will be mild for them (why take that chance?). Or because they worry about the safety of the vaccine? All medicines have potential side-effects, vaccines included.
The European Medicines Agency said more than one in 10 doses of Pandemrix (the jab being used for almost everyone in the UK) led to side-effects. These included headache, joint or muscle pain and sore arms.
Now look again at the numbers who are currently critically ill with swine flu, and then balance the risk of the disease against that of being immunised.
This graph shows that, of the deaths so far in England, 65% have been among people who would have qualified for the vaccine, among them several pregnant women.
The H1N1 virus is now a preventable illness, and it will be important to see in the coming months what effect immunisation has on death and hospitalisation.
Sir Liam revealed that posters condemning vaccination as a "weapon of mass destruction" were put up in a Birmingham hospital at the weekend.
He said it appeared to be the work of an anarchist group who also believed that 9/11 was the work of the US government.
A brief look at their website left me slightly unsure what they stand for except that government is bad, as are taxes.
The latest figures for flu reveal that the second wave continues a steady upward, but not explosive, trend.
There were an estimated 78,000 new cases of swine flu in the past week in England, up from 53,000 the week before.
In Scotland, there were around 20,000 cases and 65 people were in critical care as of yesterday.
Look at the red line and you can see that the curve is still upward, but way below July and the last epidemic of 1999/2000. But the flu season has barely begun.
More than 500,000 people are now thought to have had swine flu since the outbreak began. The number of deaths remains, thankfully, comparatively low. The latest death toll for the UK is 137.
This is part of the swine flu paradox, because we would expect several thousand deaths from seasonal flu every year, mostly in the frail elderly.
By contrast, the majority of deaths from swine flu are in people aged under 45. So although the total number of deaths is low, hospitals are gearing up for what could be their busiest winter in intensive care for a generation.
• Detailed UK weekly epidemiology update
• Swine flu figures for Northern Ireland
• Swine flu figures for Scotland
• Swine flu figures for Wales