Patch could cut risk of 'Montezuma's revenge'

A study of the needle-free vaccine shows it protected more than 70 percent of visitors to Mexico and Guatemala.

The research, which appears in the journal Lancet, also shows those who did get sick recovered a lot faster. The patch contains the poisons produced by E. coli with the idea that this primes the immune system to cope better when confronted with the real thing.

The patch is made by the biotech company Iomai.