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Venom immunotherapy: how to safely extend maintenance intervals during pandemics?

Published online: February 1, 2021

Hymenoptera stings can induce allergic systemic and occasionally fatal reactions. Subcutaneous venom immunotherapy (VIT) is the only disease-modifying treatment, able to reduce the risk of a systemic reaction to subsequent re-stings. After an induction phase, a maintenance phase follows, with intervals between injections progressively extended up to 12 weeks. However, too long intervals may decrease VIT efficacy (less protection in case of re-sting) and safety (higher risk of adverse reactions to VIT). Nonetheless, for several reasons the COVID-19 pandemic caused longer VIT delays, and no recommendations are available to manage this huge extension.

In a recent article published in The Journal of Allergy and Clinical Immunology: In Practice, Bilò et al. report the Italian experience in managing patients on maintenance VIT, during the first 3 months of the COVID-19 pandemic. Of 292 subjects undergoing VIT, 87 subjects (30%) delayed their appointments because of fear of SARS-CoV-2 infection; however, once lockdown ended, they asked to resume VIT. The authors scheduled the date of the next appointments on a case-by-case basis, without starting over with the induction phase, but taking into account personal risk profile of resuming VIT after a long period (e.g. pre-VIT severity reaction to sting, type of hymenoptera venom, diagnosed or potential mast-cell disorders, comorbities, concomitant pharmacological treatments, duration of VIT, and pre-pandemic maintenance interval). Furthermore, they analyzed the associations between adverse reactions occurred in resuming VIT and potential risk factors.

As first results, adherence to VIT was quite high, as 61% of patients respected the original appointment despite the COVID-19 pandemic. In the latecomers, VIT delay was greater than or equal to 4 months in 56% of patients, with the longest in 8% (≥ 5 months). The total amount of the maintenance dose of venom was administered in 1 day in 78% of patients. The main factor that affected the decision-making process for the new appointment was the pre-pandemic maintenance interval; in other words, usually the longer the maintenance interval, the sooner the patients resumed VIT. Other factors were pre-VIT severity reaction to sting, older age, and concomitant medications. The time extension was safe and well tolerated, as only 3 patients (3%) experienced mild adverse reactions. The risk factors identified in these 3 patients were bee venom allergy and recent VIT initiation.

Learning from the COVID-19 emergency, long VIT delays may be safe and well tolerated, as long as the following key risk factors are taken into account before resuming VIT: long pre-pandemic maintenance interval, severe pre-VIT reaction, recent VIT initiation, older age, multidrug treatments, and bee venom allergy.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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