A large consignment of seasonal flu vaccine, which was due to be circulated to 18 European countries, has been infected with deadly live avian flu virus. Had the contamination not been detected, the vaccines may have started an avian flu pandemic, killing hundreds of thousands of people.
The World Health Organization is carrying out investigations at the Austrian research facility of Baxter International, the pharmaceutical company, where the contamination happened. Baxter has confirmed that the consignment contained live H5N1 virus, which causes avian flu.
A researcher in the Czech Republic discovered the lethal contamination when laboratory ferrets that he had injected with the H3N2 flu vaccine suddenly died. The H5N1 virus becomes lethal as an injection only when it is mixed with H3N2, a process known as reassortment.
The WHO investigation team says it doesn't have evidence to suggest that Baxter had deliberately reassorted the two viruses, but "what remains unanswered are the circumstances surrounding the incident in the Baxter facility," a WHO official said.
Despite dire warnings from health officials, no avian flu pandemic has occurred as human-to-human infection hasn't happened. So far, several hundred people have died after catching the virus from poultry, although governments have warned that millions would die if people could infect each other.
Baxter is currently working on a new type of avian flu vaccine, called Celvapan, which is based on cell culture technology.
The technology, which is being developed at Baxter's research facility in the Czech Republic, by-passes the conventional process where a virus is incubated in chicken eggs. Instead, Baxter is working with the 'native' virus that does not need to be modified.
Last year the vaccine passed the first two phases of safety trials, and Baxter announced that "Celvapan combines innovative science and breakthrough production technology with the aim of protecting people against an H5N1 pandemic flu infection."
(Sources: Toronto Sun, February 27, 2009; New England Journal of Medicine, 2008; 358: 2573-84).