Researchers in the U.S. have created a ‘vaccine' they believe will help treat multiple allergies, including hay fever.
The jab contains a cocktail of allergy-causing compounds and is administered in several increasing doses over eight weeks.
The theory is that by gradually upping the amount of these triggers in a controlled way (a treatment known as immunotherapy), the immune system becomes more tolerant to them, which eradicates symptoms and provides long-term protection against other allergies.
In a new trial, patients with common allergies, such as hay fever and allergic rhinitis, will be given the new injection or a placebo.
Around one in five people has allergic rhinitis, a reaction to triggers, also called allergens, such as dust or animal dander.
Allergens contain proteins that can trigger the production of histamine, a chemical in the body that causes cold-like symptoms, such as sneezing, itchiness and a blocked or runny nose.
Whereas hay fever, also called seasonal rhinitis, is caused by pollen or mould spores at certain times of the year, allergic rhinitis can in some cases affect people all year round, when it is known as perennial rhinitis.
Treatments include antihistamines and corticosteroids, which tackle inflammation and swelling. Side-effects of antihistamines can include drowsiness, dry mouth and blurred vision, while long-term use — more than three weeks — of steroids has been linked to an increased risk of health problems such as weight gain and muscle weakness.
Immunotherapy, usually in the form of drops, can be given to those with severe allergies (typically to pollen) to try to make the immune system less reactive to a specific allergen.
The conventional treatment involves being given small doses of one allergen. However this works only for one allergy and needs to be given at three monthly intervals for years.
But in the new trial, doctors are using a cocktail of six different allergens in the same shot and it's hoped that the effects of the new jab will be lifelong. The treatment is designed to help people with moderate to severe perennial rhinitis who may or may not have hay fever, too.
In the trial at Johns Hopkins University in the U.S., 36 patients will be given increasing doses of the jab (named Allergen Immunotherapy Extract) or a placebo, twice a week for eight weeks. They will be monitored for symptom changes for more than three months. Commenting on the study, Christopher Corrigan, a professor of asthma, allergy and immunology, at King's College, said: ‘Immunotherapy is not a cure but significantly reduces symptoms in most patients.
‘Treating people with a cocktail of allergens sounds like a good idea to combat multiple allergies. But, in practice, treating with an arbitrary mixture of allergens may mean inadequate treatment for key allergens that are causing symptoms, and unnecessary treatment for others which are not causing symptoms.'