Vaccination during concurrent subcutaneous immunotherapy: safety of simultaneous application

Area of Science:

• Allergy and Immunology
• Vaccinology

Background:

• Current guidelines recommend a 1-week interval between subcutaneous immunotherapy (SCIT) and vaccinations to prevent potential adverse immune reactions.
• This recommendation is based on the assumption that co-administration may increase the risk of systemic reactions (SRs).

Purpose of the Study:

• To investigate the safety of co-administering SCIT and vaccinations, challenging the necessity of the 1-week separation interval.
• To assess the incidence of SRs in patients receiving SCIT and vaccinations concurrently or with minimal delay.

Main Methods:

• Retrospective analysis of 875 individuals receiving SCIT and/or vaccinations.
• Classification of systemic reactions (SRs) using World Allergy Organization (WAO) grading.
• Comparison of SR rates in patients receiving vaccinations alone, SCIT alone, and combined/consecutive SCIT and vaccinations.

Main Results:

• No SRs were reported in patients receiving vaccinations alone.
• A low incidence of SRs (one grade 3, two grade 2) was observed in patients receiving SCIT alone.
• Crucially, no SRs occurred in patients who received simultaneous SCIT and vaccinations, or those with SCIT injections within 4 days of vaccination.

Conclusions:

• The findings suggest that the recommended 1-week interval between SCIT and vaccinations may be unnecessarily long.
• Shortening or eliminating this interval appears safe and does not increase the risk of systemic reactions.
• This could lead to more flexible scheduling for patients undergoing both immunotherapy and vaccination.