Background: Hymenoptera venom immunotherapy (VIT) is a safe and effective approach to insect sting allergy. However, after discontinuation, relapses can occur in some patients, especially those with a high occupational risk, and they may need to prolong VIT indefinitely. In order to improve adherence, we propose extending the interval between injections of maintenance VIT (MVIT).

Objective: To evaluate the safety, effi cacy, and patient acceptance of a 3-month interval between MVIT injections in a group of Hymenopteraallergic patients who are occupationally exposed to insect stings.

Patients and Methods: We included 72 patients with severe systemic reactions to Hymenoptera stings. MVIT was administered for 4 years at intervals increasing up to 3 months and then continued for a further 2 years. Patients were informed of the risk of relapse after discontinuation and of the need for indefinite treatment at 3-month intervals.
Results: During the 3-month interval maintenance phase, only 235 local reactions (17.8%) were observed in 17 patients. Sixty patients experienced 125 field re-stings and only 1 experienced a systemic reaction with generalized urticaria.

Conclusions: The study confirms that the conventional MVIT interval of 4 to 6 weeks can be extended to 3 months in most patients with no adverse events, while maintaining safety and efficacy, improving adherence, and guaranteeing safe continuation of professional activity.

Key words: Venom immunotherapy. Patient acceptance. Safety. Efficacy. 3-month interval. Maintenance.