Wednesday, July 8, 2009

More on vaccines

Fergus Walsh (BBC News)Jul 08, 2009 16:10:21 GMT
There is a lot of hope and expectation resting on a vaccine for H1N1 swine flu. Global vaccine manufacturers have received the seed virus and are growing this to produce doses for clinical trials.
One key player will be Sanofi Pasteur, the world's biggest producer of vaccines. It has around 45% flu vaccine market worldwide.
Dr Albert GarciaCompany spokesman Dr Albert Garcia explained that last year the company produced 170 million doses of seasonal flu vaccine, with around 130 million doses for northern and 40 million doses for southern hemisphere.
I wrote last week about Novartis and Baxter, who are both producing some flu vaccine using cell culture. But Sanofi Pasteur relies wholly on the slower and seemingly outdated process of growing the vaccine in fertilized chicken eggs. Why?
"We find egg-based technology is the most reliable method for producing flu vaccines in bulk" said Dr Garcia. "It is very robust." In other words, if something is not broke, why try to fix it?
Flu vaccines have been created successfully for decades using eggs. Cell culture production is much more recent and is still an emerging technology which has experienced teething problems. But it is several weeks, even months faster, important in a pandemic.
So how much vaccine might be available? By my reckoning, it takes three eggs to produce a trivalent seasonal flu jab - one egg per strain of flu. So does that mean the company can produce not 170 million doses in the coming twelve months, but 510 million?
Dr Garcia said: "It's not so simple". He explained:
"We don't know what the yield of H1N1 vaccine will be, nor do we now how many micrograms of vaccine will be needed in each dose. The aim will be to produce as many doses as possible in order to protect the maximum number of people. But it all depends on the outcome of the clinical trials."
It's also not clear whether people will require one or two jabs. Against seasonal flu one vaccine is given each autumn, but it's been presumed that two doses will be required to give protection against a pandemic strain.
Sanofi Pasteur is one of the few manufacturers producing seasonal doses for the southern hemisphere (along with CSL in Australia).
So what will happen to this autumn's production - due to start in October - of next year's doses of seasonal flu vaccine, due to be distributed in spring 2010?
Interestingly, it seems the WHO has not yet made a decision about whether to sacrifice this production by asking SP and CSL to switch entirely to making H1N1 swine flu.
"We are at the disposal of the WHO" says Dr Garcia. "We have not had a request to switch totally to H1N1 pandemic vaccine."
That decision doesn't need to be taken yet, until clinical trials of the H1N1 vaccine have been completed. But by September, someone will have to decide whether to abandon seasonal flu vaccine for the time being, and concentrate on swine flu.

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