BETTER VACCINES FOR THE NEXT PANDEMIC; NEW TECHNOLOGIES PROMISE AN END TO SHORTAGES
December 9, 2009
The H1N1 immunization effort should be a wake-up call to health officials: We are woefully unprepared to deal with a true pandemic of a highly lethal virus, says Dr. Henry I. Miller, a physician and fellow at Stanford University's Hoover Institution.
The trouble with our current vaccine production system is that it is not rapidly scalable to demand. It is an 80-year-old system that depends on harvesting the vaccine from fertilized chicken eggs. Manufacturers grow the virus in the eggs until there is a sufficiently high titer, and then the virus is harvested, killed and purified. The entire process takes months. To harvest a suitable amount of vaccine for flu season requires millions of eggs. In 21st century America, we are waging war on a lethal infectious disease with World War I-era technology, says Miller.
Fortunately, there are two newer, far superior ways to create vaccines, says Miller. The first is a process using recombinant DNA, or "gene-splicing," technology to create a vaccine that induces the body to make its own antigen, and then to produce antibodies to that antigen:
- Researchers produce DNA of the target virus gene in a laboratory and introduce it into a circle of DNA called a plasmid, which acts as a carrier.
- The plasmids containing the viral gene can easily and quickly be grown in large amounts.
- The entire process, once the viral DNA is isolated, takes only a few days; this process is cost-effective and produces a vaccine with numerous advantages over the traditional versions.
Another promising new vaccine process uses cell cultures of various kinds as a stand-in for the eggs in the traditional model:
- Manufacturers expose animal or insect cells grown in tissue culture to live virus, allow it to multiply and then harvest, inactivate and purify the virus particles.
- This method saves time in scaling up to meet vaccine needs and avoids relying on eggs, which is cumbersome and could be vulnerable to infection if there were an outbreak of avian flu - thereby creating unacceptable and possibly lethal delays for the production process.
Research and testing of DNA vaccines in particular must be expanded. Other vaccine manufacturers should be encouraged to branch into new technologies, says Miller.
Source: Dr. Henry I. Miller, "Better vaccines for the next pandemic; New technologies promise an end to shortages," Washington Times, December 7, 2009.
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