| Sometimes I'm just slow. I've been copying and posting the ILI charts for England and Wales on the news diary every week, but it didn't occur to me to do a comparison, with other countries like the US. Until just now in the heat ;-D of a debate on the justification, or lack thereof, for the use of adjuvants in the UK for the current pandemic, when 2 pieces of information came together and a lightbulb went up in my head!
The first is the seropositive rate among clinical trials subjects in Germany earlier this summer, for the H1N1 vaccine, by GSK. The following table is from their EMEA file:
At the time, I wondered whether there was something wrong with their test, that the seropositive rate was so high. I should have had more faith. Testing for antibodies is the bread and butter of the laboratory part of vaccine companies like GSK, and they have, well, substantial budgets. In any case, after vaccination, the seroprotection rates were 98.4% and 97% for adjuvanted and unadjuvanted groups respectively, which are exceptionally high numbers. So the initial seroprevalence was probably correct, or close enough to be correct.
The second piece is just lining up the dates and weeks of the ILI charts from the UK (England and Wales to be precise, but 'UK' is shorter and easier!) and the US, which produced the following composite picture (top panel: US, bottom panel: UK). The dates are lined up so that if you drop a vertical line from the top to the bottom chart, you're looking at the same point on the calendar dates.
One hint for looking at these charts is, if you want to know the number of people infected in one wave relative to another, just compare the size of the area under the curve. So, as you can see, the US had a small first wave which happened earlier, and which was just a fraction of the previous seasonal flu wave. Now they are having a very big second wave.
In comparison, the UK had a very big first wave which happened later (makes sense, since it originated from across the Atlantic). This first wave was, by my rough 'eyeballing' estimate, about 2-3 times the size of the previous seasonal wave. And now in the second 'wave', we have these wavelets bumping along the bottom, with the exception of Wales (broken green line) which had the smallest first wave that started last, compared to other regions. And now Wales is having somewhat bigger waves than the rest.
So, I'm thinking, does this mean that we are already running out of susceptible subjects? If you have a significant proportion of population already immune, then transmission is much slower, more sporadic, and you don't see that huge rising wave like in the US.
Also, seasonal flu in the UK starts and ends earlier than in the US, as you can see for 08/09. So we are getting into the flu season here, and if we are not seeing huge numbers, it might mean something, you know.
Just to be (more) sure, I did a couple more checks. I looked around the various UK sites, and found this page with this bit of news:
Latest news - 12 November 2009
There were 64,000 new cases of swine flu in England last week, down nearly 25 per cent on the week before when there were 84,000 new cases.
Hmmm, down nearly 25%. That's not exactly how a rising pandemic wave would behave, is it?
I also looked at the NHS Direct syndromic surveillance data, for fever and cough, downloaded from the HPA site. NHS Direct operates a 24 hour phone service for people to call if they get sick and need advice or care. The number or percentage of calls for a particular symptom can be used for surveillance analysis.
So I downloaded it, and the document says this on the first page:
Please note: The NHS Direct system change that was introduced on Saturday 4th July to deal with the increased call volumes experienced due to swine flu has been discontinued over the weekend of 3-4 October.
Apparently, in July the volume of calls was such that they had to do a system change. The signficant part, for me, is that that change was reverted back to their previous service, on Oct 4. I don't know if we can interpret the data during that period, but we can look at what happened after they changed back to their previous system. I highlighted (pale yellow) the corresponding periods from Oct 4 to now, and in 2008, for comparison.
The difference between 2009 and 2008 is very small. It could be that lots of people are getting their tamiflu directly by calling or answering a list of questions online, and so bypassing these different surveillance systems. However, when I looked at the Weekly National Influenza Report, I found this chart.
Nope, that hypothesis was incorrect. The fall in cases is real. (But I did scratch my head a little, over the regular bumps up and down. I don't know, maybe that is due to variations on different days of the week?...)
Anyway, I also tried looking for hospitalisation data, in the off chance that many people were so sick they went straight to the hospital, but unfortunately, I was unable to find it. I then tried looking for some mortality data. I said tried because even though I found those, the information is a little, well, incredible, so I don't know if I'm missing something. I'm just going to show you these 2 charts, showing all deaths registered by week, and respiratory deaths respectively. The big peaks in the middle (blue and green) are the seasonal flu deaths. The period since the beginning of this pandemic, is represented by the later part of the blue line, and the red line just starting.
So I'm looking at them and thinking, am I seeing things? Or, more accurately, NOT seeing things?! Where are the excess deaths due to the pandemic? We had this huge wave in the summer, and it didn't make a noticeable difference in the mortality curves??
Somebody help me out here. I'm just so confused. Either we've done exceptionally well, and the pandemic has come and gone and we'd hardly registered substantial numbers of deaths, or... what? I have no idea.
In any case, the original question that started this quest, namely, what is the point of giving millions of people adjuvanted vaccines of uncertain safety in a mild pandemic, has now acquired a new dimension, namely, what is the point, of giving millions of people adjuvanted vaccines of uncertain safety in a mild pandemic, when the worst may be over?? The HPA (or whoever is supposed to do this stuff) should conduct some seroprevalence studies, as a matter of priority urgency, to see how many people are still seronegative, because it may well give us some insight as to how best to move forward with the vaccination saga - um, sorry, programme - that will protect the most people with the least possible adverse effects!! |
