Could the sneezy, runny-eyed misery of hay fever one day be a thing of the past? Scientists are reporting encouraging results from early tests of a vaccine they hope will give long-lasting relief from this seasonal scourge.

The experimental vaccine has been tested on only a couple of dozen people so far, but it substantially relieved symptoms for those who received it in six weekly shots, and the benefit lasted for at least two years, doctors reported in Thursday's New England Journal of Medicine.

The vaccine "holds great promise," said Dr. Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases, which helped fund the study. "A short course of immunotherapy that reduces allergic symptoms over an extended period of time will significantly improve the quality of life for many people."

Up to 40 million Americans suffer from hay fever, caused by an allergy to ragweed pollen, which is most common in the Northeast, Midwest and the South, especially in late summer and early fall.

To relieve symptoms, many take antihistamines and other medications. But the only option for longer-lasting relief has been dozens of shots over three to five years to try to sensitize the immune system. This helps only about a third of patients, and many of them give up before the series of shots is completed. There is also the risk of an allergic reaction to the shots.

The study tested a vaccine made by California-based Dynavax Technologies. It was led by Dr. Peter Creticos, director of the Johns Hopkins Asthma and Allergy Center, and included researchers from the company.

Hay fever sufferers were given either six shots of the vaccine or dummy shots. The vaccine did not improve the main measurement doctors were using to gauge its effectiveness -- a drop in a protein in mucus that is normally lower after traditional allergy shots.

However, the vaccine reduced symptoms of sneezing, runny nose and eyes, and itchy ears and throats by 60 percent on average in the 14 who received it compared with the 11 who did not. The eight vaccine recipients who stayed in the study a second year said they continued to benefit even though they were not given any more shots.

"They're all saying the same thing to a T -- `I don't have problems in the fall anymore,"' Creticos said.

The company plans a larger study of the vaccine.

Dr. Jordan Fink, a Medical College of Wisconsin professor and past president of the American Academy of Allergy, Asthma and Immunology, said a vaccine that changes an allergic individual's immune response without the risk of big side effects has been a goal of allergists for years.

The vaccine needs far more study, but "may be a boon to treatment of allergic patients," he said.