150m doses of vaccine distributed worldwide
A brief update from the World Health Organization's Dr Keiji Fukuda. He estimates that more than 150m doses of H1N1 pandemic vaccine have been distributed in 40 countries and the safety profile continues to be similar to seasonal flu vaccines.
He could shed no light on when the H1N1 swine flu strain would be incorporated into the normal trivalent seasonal flu jab or when the pandemic might be declared to be over: "It's fair to say that we haven't got through the pandemic and there could be unexpected events."
So what about viral drift, where all strains of flu change? Again Dr Fukuda would not be drawn on whether the H1N1 strain might become more or less virulent:
"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."There were questions too about a CDC (Centers for Disease Control and Prevention) estimate from Dr Martin Cetron that the pandemic has an estimated fatality rate of .018% from pandemic flu which would make it 100-fold lower than the 1918-19 pandemic. Dr Fukuda suggested it was too early to make hard and fast comparisons between this and other pandemics (beyond noting that this continues to be a largely mild pandemic).
"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."The WHO has a couple of new notes on its website, one in particular on mutations, which you may find interesting (and reassuring). In brief, the WHO has been informed of 96 H1N1 virus strains which are resistant to Tamiflu. This is not widespread resistance, but it has happened in a number of countries including some clusters in people who are severely immuno-compromised.