Maintenance venom immunotherapy administered at 3-month intervals is both safe and efficacious

Maintenance venom immunotherapy (MVIT) is usually administered to patients with venom allergy at 4- to 6-week intervals for at least 3 to 5 years. The small number of studies assessing the possibility of extending the maintenance interval (MI) included either too small a population and patients with only vespid and not bee venom (BV) allergy or relied on reaction to field stings only.

We sought to assess the safety and efficacy of MVIT given at 3-month intervals to a large population of patients allergic to both yellow jacket venom and BV.

In all patients undergoing venom immunotherapy, MI was gradually extended to 3 months. Systemic reactions (SRs) to immunotherapy injections or to field stings were regularly recorded. Some of the patients were also deliberately sting challenged during the 3-month interval. Patients discontinuing MVIT were interviewed regarding their responses to field re-stings, and in some of them, an in-hospital sting challenge was performed.

One hundred sixty patients mostly allergic to BV were enrolled in the study. Failure to reach the 3-month interval was observed in 6 (3.8%) patients, originating in failure to reach the full maintenance dose in most of them. SRs to MVIT administered at 3-month intervals were observed in 2.6% of the patients. One of 36 patients who experienced a field sting during the 3-month interval had an objective mild SR (2.8%). Two (4.5%) of 44 patients who were deliberately stung during the 3-month interval had mild SRs. After discontinuation of MVIT, 2 (8.3%) of 24 patients who experienced a field sting had an SR. Both were allergic to yellow jacket venom. Three to 82 months after discontinuation of MVIT, 22 patients allergic to BV were sting challenged. Only one (4.5%) patient had a mild objective SR.

The conventional 4- to 6-week MI can easily be extended to 3 months in most patients without any adverse events. MVIT given at a 3-month interval is safe and effective while being administered, as well as after its discontinuation. This fact should be applied to almost every patient allergic to insect venom.