Vaccine Patch May Be 'Excellent New Weapon' Against Travelers' Discomfort

An infectious disease expert at The University of Texas School of Public Health at Houston is leading research of a pain-free vaccine for travelers' diarrhea - a condition that strikes an estimated 20 million international travelers each year.

Herbert L. DuPont, M.D., professor and director of the Center for Infectious Diseases at the UT School of Public Health and the Graduate School of Biomedical Sciences, is the principal investigator studying the effectiveness of a needle-free patch that delivers the travelers' diarrhea vaccine.

Results of the Phase II trial were presented in Chicago at the 47th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC). DuPont's clinical trial found that travelers in Guatemala and Mexico who received the vaccine patch were significantly less likely to be sickened as compared with travelers who received a placebo.

Iomai Corporation developed the vaccine and plans to begin Phase III testing in 2008.

"The results presented at ICAAC are the most robust ever shown in the prevention of travelers' diarrhea, and they suggest we may be near a turning point in the prevention of this common, often-serious disease," said DuPont, who also is the Mary W. Kelsey Professor of Medical Sciences at The UT Medical School at Houston. "If Phase III trials for the vaccine validate these results, those of us in travel medicine will have an excellent new weapon in our armamentarium."

If approved, the Iomai vaccine would be the first vaccine for travelers' diarrhea available in the United States.

The "Trek Study" found that of the 59 individuals who received the patch-based vaccine only three suffered cases of moderate or severe diarrhea, while 23 of the 111 who received a placebo suffered moderate or severe diarrhea - a 75 percent reduction. One of the 59 volunteers in the vaccine group reported severe diarrhea, compared with 12 of the 111 in the placebo group - an 84 percent reduction.

"We have demonstrated that vaccinated travelers can dramatically cut their risk of diarrhea by using our needle-free patch," said Gregory M. Glenn, M.D., Iomai's founder and chief scientific officer. "Those who received the Iomai vaccination were much less likely to get sick, and those who were sickened had far milder illness than those who received a placebo. These are clinically significant results that suggest that the patch vaccine will address the most significant unmet need for travel medicine: prophylaxis for travelers' diarrhea."

The study followed 170 travelers to Mexico and Guatemala. Each volunteer received either two doses of the Iomai vaccine patch or a placebo, two-to-three weeks apart, with the last dose administered a week before travel.

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