By Barbara Hesselgrave
European health authorities are unraveling how an “experimental virus material” focused on a seasonal flu became contaminated with H5N1 live bird flu virus and was distributed throughout Central Europe.
The tip-off to a serious problem began in early February, when researchers at a Czech subcontractor facility who inoculated ferrets with the experimental vaccine reported the animals died immediately.
While this agent reportedly was never intended for release, the incident is considered a serious error involving dangerous pathogens, and European officials are saying an accidental release could have resulted in “dire consequences.”
The European Medicine Agency recommended in December that Deerfield, Ill.-based Baxter International be allowed to sell its product, named Celvapan, throughout Europe.
Difficulty in manufacturing large quantities of vaccine has caused many countries to stockpile the protective drugs, however, Baxter’s use of wild type flu viruses is felt to be more dangerous than the attenuated, weakened viruses other manufacturers use. A distribution of live virus proficiency test kits sent out by a manufacturer in 2005 that included the H2N2 virus, the one responsible for the 1957 pandemic, required global efforts to quickly retrieve and destroy the vials of virus sent to 18 countries.
The latest contamination, a mixture of two live viruses — human H3N2 and avian H5N1 — is the deadly stuff of Hollywood screenplays. European health officials describe that people are commonly infected with H3N2, but less so for H5N1. However, if an individual had been co-infected with both, and was then exposed to the contaminated material, they could serve as an incubator for a hybrid virus able to transmit easily among people. Officials say this “reassortment process” is one of two ways that pandemic viruses are created, and research performed in the U.S. by the Centers for Disease Control and Prevention in 2008 found that the two viruses mate easily, and their “offspring” retain a powerful killing ability.
Dr. Angus Nicoll of the European Centre of Disease Prevention and Control said from Stockholm that officials aren’t 100 percent sure the mixture contained live virus, but the fact that ferrets, “who are susceptible but don’t die from human flu strains,” died immediately is fairly clear evidence that it likely did.
What is still unclear is how live virus, the H5N1, would have become mixed with the live H3N2. Baxter spokesman Christopher Bona, speaking from Deerfield, said that the error originated at its Austrian research facility. That facility had contracted with Avir Green Hills Biotechnology to make what Bona described as an “experimental virus material,” based on human H3N2 viruses, but one that was never intended for vaccine production. Avir Green Hills then sent the material to four subcontractors in the Czech Republic, Slovenia and Germany.
Sidestepping just how this contamination of the two live virus agents happened, claiming to do so would “give away proprietary information about Baxter’s production process,” Bona told The Canadian Press that Baxter has identified “how the contamination happened and has taken steps to ensure it doesn’t happen again.”
Biosecurity experts, meanwhile, are most unhappy.
Bona said Baxter helped the various companies involved destroy the contaminated material and clean up facilities. Staff members who had been exposed were offered Tamiflu, an anti-viral drug from GlaxoSmithKline.