VOA常速英语:Researcher Develops Inhalable Measles Vaccine

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Most vaccines are given as a liquid shot using a needle and syringe, but this method can lead to infection if needles are reused or not disposed of safely.

Bob Sievers is a chemistry professor at the University of Colorado in Boulder, and the head of a small chemical company called Aktiv-Dry. With a grant from the Bill and Melinda Gates Foundation, Sievers is developing a dry powder form of the measles vaccine that would be inhaled, instead of injected.

The first advantage of a needle-free vaccine, says Sievers, is that it does not hurt. "There's no pain associated with inhaling an aerosol, like there is getting a needle-stick."

Since an inhalable vaccine would eliminate the need for injection, vaccine recipients would not be at risk of infection from reused needles. Health care providers would be safe from accidental needle-sticks, and there would be no contaminated needles to dispose of.

"You can step on a used needle that's thrown out in the trash dump, and contract hepatitis B or something else that would really be only because you had used needles in delivering the vaccine for measles."

Liquid measles vaccine is usually made up in batches, with multiple doses in a single vial. If something happens to contaminate the vial, then everyone vaccinated with that batch would be infected.

Sievers explains his powder vaccine will be distributed as individually-wrapped doses, so "there's never a chance you're going to be cross-contaminated by the person that came before you."

Another problem with the liquid vaccine is that once it's mixed, it must be used within six hours. That's not the case with Sievers' inhalable version. "You can keep it for two years, as a dry powder," he says.

Sievers' team has also worked hard to keep down the cost of their vaccine, and it will not cost any more than the current liquid vaccine.

Animal studies have shown the new vaccine is both safe and effective at preventing measles infection. Sievers plans to begin human clinical trials in India in 2010. If all goes well, he says the inhalable dry powder measles vaccine could be available for use in two to four years.

And he adds that in the future, the same method could be used to create inhalable dry powder versions of other vaccines and medications.

Sievers spoke about his work this week at the annual meeting of the American Chemical Society, where he was presented with an Astellas Award for his significant contribution to improving public health.