The current situation and the next peak
Don't be fooled into thinking that H1N1 swine flu has disappeared completely, even if it is attracting less media interest. The virus is still at large in the UK. On the morning of 19 August, there were 263 people in hospital in England with the virus, 30 of them in intensive care. That is exceptional for the time of year.
Having said that, there is much less swine flu about.
Sir Liam Donaldson's weekly briefing to journalists is extremely helpful and has allowed us to track the progress of the virus in England and Wales. Here are a few of the main points:
• estimated number of cases of swine flu in England in the past week: 11,000 (possible range: 6,000-25,000)
• weekly GP consultation rate for influenza-like illness in England and Wales in the week ending 16 August: 21.1 per 100,000 people
• weekly consultation rate has fallen by 37% from last week to this week
• deaths related to swine flu in England now 54 with five in Scotland, giving a UK total of 59
Now for some graphs.
Above you can see the weekly consultation rate for influenza-type illness. The red line (the current rate) continues to show a sharp decline. The other lines show activity from flu in previous years.
The pie chart above needs careful reading. For the small number of people who have died, it shows what their health had previously been.
As you can see, 52% had severe underlying medical conditions, and 21% had been previously healthy. The rest had some kind of health problem, mild or moderate.
Remember, though, that the percentages are based on very small numbers. The 21% figure suggests that, so far, 11 entirely-healthy people have died in England after contracting swine flu.
What everyone wants to know is when the next peak will come. Two graphs presented by Sir Liam illustrate how difficult this is to predict:
This shows the path of the 1957-58 pandemic in the UK. You can see that the peak happened in the first autumn, just after pupils had returned to school. That could be what happens next month.
This shows the 1968-70 pandemic. By contrast, there was a small peak at the end of the first winter, but a far larger peak in the following flu season, a full 18 months after the first case in the UK. So perhaps that could happen this time as well.
Clearly, it would be better if the second scenario happened this time, as it will enable immunisation of at-risk groups to be completed.
Update 1534: Finally, some interesting guidance from the World Health Organization on antiviral use. It says that otherwise-healthy people who get infected and have uncomplicated illness do not need oseltamivir (often sold as Tamiflu) and zanamivir (Relenza). The difficulty, of course, is that in order to be effective, antivirals need to be taken soon after the onset of symptoms - usually well before people know whether they have are going to get complications.
The UK government's policy is to make antivirals available to anyone who is suspected of having H1N1 swine flu.
The WHO guidance will add to the debate about whether antivirals should be so freely available.
"We believe a safety-first approach of offering antivirals, when required, to everyone remains a sensible and responsible way forward. However, we will keep this policy under review as we learn more about the virus and its effects."