Researchers have successfully used an experimental DNA-based vaccine to protect against ragweed allergies, commonly known as hay fever, after just six injections.

This new therapy holds the promise of, one day, eliminating the need for traditional medicines targeting allergy symptoms such as nasal steroids and antihistamines.

The study, conducted at The Johns Hopkins University School of Medicine during two autumn ragweed seasons in Baltimore, MD, enrolled 25 volunteers, ages 23 to 60, with a demonstrated history of ragweed allergy. Fourteen people received the vaccine, administered as six weekly shots, while 11 others received placebo injections.

During the test period, allergic symptoms were monitored and recorded, right down to how often volunteers' noses ran and how many times they sneezed. Compared to the placebo group, those who received the vaccine exhibited a 60 percent reduction in all of their allergy symptoms, including sneezing, runny nose, watery eyes and itching.

Relief from allergic symptoms continued undiminished in the second year, even though no more vaccine was administered. Lead investigator Peter Creticos, M.D., medical director of the Johns Hopkins Asthma and Allergy Center in Baltimore, explained that such prolonged relief is an important part of his team's findings because it appears that the vaccine's efficacy doesn't wear off quickly. A new study, currently under way, will further examine the drug's lasting effects in a larger group of participants.

Creticos' current findings are published in the Oct. 5 issue of the New England Journal of Medicine.

"This therapeutic intervention heralds a major advance in the treatment of allergic rhinitis," says Creticos. "Long-lasting relief can be achieved with a concise, six-week injection regimen, as opposed to the current, tedious, four- to five-year course of treatment with allergen immunotherapy."

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