It works by exposing them to tiny amounts of peanut though their skin. Scientists enrolled 413 infants with peanut allergies in a trial. For a year, 244 of them wore a Viaskin patch containing 250 micrograms of peanut protein or 0.01% of a peanut. The other 118 wore a placebo. The patches had to be worn for 23 hours a day, and changed once daily. After a year, 67% of the Viaskin wearers could tolerate a few peanuts. But only 34% of the placebo group could do the same.