TORONTO — At least one flu vaccine manufacturer has received and others will be receiving shortly swine flu seed strains, the basic building block for the production of influenza vaccine, the U.S. Centers for Disease Control and some vaccine makers confirmed Wednesday.
That means the race is on to produce pilot lots of swine flu vaccine that can be tested for safety and efficacy, and to determine how large a dose and how many shots are needed to protect people against the new H1N1 virus.
Sanofi Pasteur, the world's largest producer of flu vaccine, announced in a statement that it had received the seed strain from the CDC and would begin to produce a "working stock" immediately at its newly certified facility in Swiftwater, Pa.
Donna Cary, director of media relations, said having the new facility will allow Sanofi to begin the preparatory work for commercial scale production of H1N1 vaccine while it finishes its run of seasonal flu vaccine in the company's older nearby facility.
Competitors with just one facility may not be able to take as many preparatory steps as Sanofi until they have finished production of their seasonal influenza vaccine. It's estimated vaccine makers will finish making the seasonal flu vaccine sometime late next month or into July.
"We have some flexibility here that gives everybody some options," Cary said from Swiftwater.
Sanofi's new plant can produce 100 million doses of trivalent seasonal flu vaccine, which protects against two subtypes of influenza A and one of influenza B. The older facility can produce 50 million doses of trivalent vaccine a year.
The working stock is made by growing a volume of virus in eggs. Each flu virus has its own growth characteristics and quirks, and over the next few weeks manufacturers will be tweaking their processes trying to get the seed strains to grow to high yield in eggs.
A spokesperson for GlaxoSmithKline, the company that holds Canada's pandemic vaccine contract, said it has not yet received the seed strain. GSK would make pandemic vaccine for Canada at its production facility in Ste-Foy, Que.
"We understand that the CDC and the other laboratories are in the process of shipping the strain to all relevant manufacturers, including GSK," Marie-Christine Beauchemin, a spokesperson based at the company's Montreal office, said in an email.
"We should receive it soon."
At least two seed strains have been sent out from the CDC.
One was made at CDC using reverse genetics, a patented process that allows scientists to create a hybrid virus containing the two external proteins of the flu virus - the H1 and N1 in this case - fused to six genes from another virus that has been shown to grow well in eggs.
The patent rights to reverse genetics are held by MedImmune, the Gaithersburg, Md.-based maker of the inhaled flu vaccine FluMist. (FluMist is not licensed for use in Canada.)
The other seed strain was also a hybrid - called in the language of flu a reassortant - made by a laboratory at New York Medical College, in Valhalla, N.Y., which has been making vaccine seed strains for decades.
Doris Bucher, who runs the lab, explained the new H1N1 was allowed to swap genes with another high growth human virus in eggs, producing its own hybrids. This process of producing a seed strain, called the classical method, carries no patent protection.
Bucher said the process involves seven rounds of injecting viruses into eggs and harvesting the offspring viruses 42 hours later.
For this project, she said, the pressure was on to produce a virus with good growth characteristics, and to do so quickly.
"Everybody in the lab - everybody - worked so hard on this," Bucher said. "We were working at least six, seven days a week on this."
She said the seed strain they produced seems like a solid performer. "This one certainly looks very good.... It looked good all the way through."
So far only a few countries have announced they will purchase H1N1 vaccine - the United States, Britain, France, Belgium and Finland among them. But more are known to be negotiating in the wings; at least 16 countries have previously signed advance purchase orders for pandemic vaccine.
Cary said Sanofi is in talks with other countries, but to date has only announced the U.S. contract.
"Like other companies, we have pandemic contracts with other countries. And they're all in various stages of the process of whether that applies to the H1N1 or not. Certainly discussions are ongoing," she said.
In Canada, the federal government said Tuesday it is in talks with GSK on the development and production of an H1N1 vaccine, if it is deemed necessary, but refused to comment further.
Sanofi and GSK are among several companies making vaccine for the U.S., which has so far committed to buying enough vaccine and adjuvant - compounds that boost the potency of vaccine, allowing less to be used for each person - to protect 20 million Americans. Sanofi's piece of that contract is worth US$190 million while GSK's portion is worth US$181 million.
Earlier this week, officials of the World Health Organization said they'll wait till the last minute to make recommendations on production of H1N1 vaccine, hoping to be able to gauge from the virus's behaviour during the Southern Hemisphere winter what kind of a threat it poses
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