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Allergy Vaccine: 6-Shot Cure?

Study Shows Just 6 Weekly Vaccinations Gave Relief From Ragweed Allergy
By
WebMD Health News
Reviewed by Louise Chang, MD

Oct. 4, 2006 -- Allergy sufferers got at least two ragweed seasons of relief after only six weekly shots of an experimental vaccine.

The finding comes from a small clinical trial conducted at Johns Hopkins University. The trial tested a new kind of allergy vaccine in 25 people with ragweed allergy -- also known as fall hay fever.

The proof-of-concept study was too small to prove anything. But the results so far have study leader Peter S. Creticos, MD, brimming with enthusiasm.

"For many of these people, we have wiped out the disease of ragweed allergy; it is a cure, but we don't know how long that cure will last," Creticos tells WebMD. "These people will throw away their allergy medicines during August, September, and October when hay fever is driven by ragweed. And if this works for ragweed, there is no reason why it can't work for other allergiesallergies."

Creticos is medical director of the Johns Hopkins Asthma and Allergy Center. He has in the past received consulting fees and grant support from Dynavax Technologies, the vaccine manufacturer. However, the current study was sponsored by the Immune Tolerance Network, which is funded by the National Institutes of Health.

The study appears in the Oct. 5 issue of The New England Journal of Medicine.

Vaccine Turns Allergy Off

When the body encounters a harmless foreign substance, it is supposed to get rid of it with appropriate, protective immune responses. Allergies happen when a substance -- an allergen -- sets off an allergic reaction instead of a protective immune response.

If that were the end of it, allergy wouldn't be such a big deal. But for many sufferers, the allergic process becomes a persistent, whole-body immune response that results in swelling, itching, sneezing, dripping, and/or wheezingwheezing.

The experimental allergy vaccine takes advantage of a trick scientists learned from bacteria. Bacteria carry a specific DNA segment that triggers a specific kind of immune response in humans. This immune response shuts down allergy-type immune responses and triggers protective immune responses.

The Dynavax vaccine links a ragweed particle to this bacterial DNA sequence. It's supposed to make the immune system of a person with ragweed allergy act just like the immune system of a person without ragweed allergy, says David Broide, MD, of the University of California, San Diego. Broide, one of the study investigators, is a senior advisor to the Immune Tolerance Network.

"When this vaccine is injected into a patient, the immune system sees the ragweed component not as ragweed allergen but as bacteria," Broide tells WebMD. "It calls up the protective immune response instead of the allergic response. So the immune response is being fooled into making the correct response."

Experimental Vaccine vs. Traditional Allergy Shots

Creticos and colleagues originally enrolled 25 people with ragweed allergy in their study. Half got the ragweed allergy vaccine -- one shot a week for six weeks, with gradually increasing amounts of ragweed allergen -- and half got fake injections.

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