Background: The objective of this study was to determine whether a cluster scheme of allergic immunotherapy
(AIT), starting administration of the therapeutic extract with the highest available concentration vial (vial B) of
Allergovit®, affords adequate safety and tolerance under conditions of routine clinical practice.
Methods: An observational study with retrospective collection of data from protocolled patients’ medical records
was designed. Patients of 5–65 years old with diagnosis of rhinitis with or without bronchial allergic asthma and
hypersensitivity to pollen were selected. Patients were treated with subcutaneous Allergovit®, starting with cluster
high doses (500 + 500 TU/1500 + 1500 TU/3000 + 3000 TU) on days 1/8/15 of the build-up phase and 6000 TU
monthly on the maintenance phase for 2 years.
Results: One hundred and ten patients were included being 51.8% (57) females with a mean age of 30.9 years
(95% CI 28.1–33.6). During the first year of AIT, 46 patients suffered 69 adverse reactions (5% of injections). Local
reactions were observed in 3.03% of injections (60), and systemic reactions in 0.46% of injections (9). Fifteen systemic
reactions were observed in 11 patients during 2 years: 3/Grade 1, 11/Grade 2 and 1/Grade 3, all of them were resolved
in 1 day.
Conclusions: Cluster AIT reduces the vaccination build-up period, reaching the desired maintenance dose within
2 weeks. The low number of local and systemic reactions observed, the low severity and the resolution of all of them
mostly in only 1 day, and the similar safety results observed in other cluster schemes allow to conclude that the cluster
scheme evaluated (500 + 500 TU/1500 + 1500 TU/3000 + 3000 TU) was safe for the patients.