There is no commercially available vaccine for avian influenza type H5N1, but we're getting close. It's almost easier to list who isn't working on one than naming who is. And while an avian flu vaccine presents some hurdles, all can be overcome fairly quickly.
The most time-consuming is that unlike our seasonal flu shots, which go straight from producer to distributor, avian flu vaccines must first be tested to determine what dose will provide optimal protection. The largest trial so far, conducted jointly by the National Institutes of Health and the French pharmaceutical maker Sanofi-Pasteur, safely produced immunity in healthy adults.
That vaccine is now being tested on children and the elderly, but Uncle Sam has enough faith in it to have already purchased $100 million worth. Chiron Corporation of California has a $62.5 million contract to deliver vaccine to the U.S. next year. Other companies that are running trials or soon will include Britain’s GlaxoSmithKline, MedImmune of Maryland, Swedish-Dutch Akzo Nobel, and Belgian-based Solvay S.A.
Yet even an approved vaccine would be stuck with a 50-year-old method, wherein ya gotta break a few eggs (tens of millions, actually) and consume at least six precious months. Virus collected each February is first grown in one set of eggs to make "seed vaccine," then injected into those many millions of eggs, grown, extracted, and processed.
But two new biotechnology methods will scramble the egg technique and slash manufacturing time, allowing a quick and life-saving turnaround in production of new doses.
One is reverse genetics, which precisely replicates only the viral genes that must be grown into vaccine. Reverse genetics "means instead of employing actual virus you're just cloning the genes," explains Richard Webby, a virologist at St. Jude Children's Research Hospital in Memphis.
"The process of getting the proper strain in a chicken egg is fairly random and you may have to start over," he says. Reverse genetics means accurate replication first time, every time. And it’s done in less than a week.
Webby's lab engineered the strain used in the successful Sanofi-Pasteur vaccination and that of other companies. A reverse-engineered strain has an added advantage in that natural strains kill chicken eggs, leaving a small window of opportunity to extract the precious contents. Genetically-engineered virus never kills the egg.
The second speed-up technology will replace those tens of millions of eggs with cell cultures. Lab technicians will just open the freezer, push aside the ice cream, pull out the cells, and grow them quickly in vats in whatever-sized batches they need. Chickens need not apply.
Many biotech companies are experimenting with cell cultures from various animals, but importantly among them is Solvay which says it will use canine cultures to produce its avian flu vaccine.
Other companies like Michigan-based SoloHill Engineering, which has been experimenting with cell-cultured vaccines for years, are looking to license Solvay's technique. SoloHill CEO David Solomon says he thinks the combination of reverse genetics and cell cultures can cut the entire vaccination production process "to 90 days or less."
The one truly special problem with avian flu vaccines is that since we've never been exposed to anything very similar to H5N1, a single dose won't be enough to confer full immunity. That would seem to require doubling the batch. Further, the second dose would have to be injected several weeks later, extending the advance time needed for vaccinations.
But an annual H5N1 vaccine might not be required. When Chiron researchers tested blood from people who had received an experimental vaccine against a 1997 strain of H5N1, they found it provoked a strong immune reaction with H5N1 from 2004.
For all the talk about a virus mutating like gangbusters, in this way at least it seems like the pokey little puppy. We might have strong protection for years after immunization. At the very least, after the initial year only one injection should be required.
As to the amounts, pharmaceutical companies could tremendously stretch supplies with adjuvants – chemicals that magnify a vaccine's effect. Many companies, including most listed above, are developing and testing adjuvant-assisted vaccines.
GlaxoSmithKline says its version will be powerful enough to multiply current production capacity of 150 million doses to 7 billion shots, or enough to vaccinate 3.5 billion people. Given problems in distribution, say health officials, that's as many as could be practically immunized each year.