MMR Vaccination and Hen's Egg Allergy: Bridging the Gap Between Evidence and Clinical Practice.

Background: Measles has re-emerged in recent years as a public health concern in the context of insufficient vaccination coverage. Some children experience significant delays in receiving, or refuse to take, the measles, mumps and rubella (MMR) vaccination, often due to concerns related to hen's egg allergy (HEA). Methods: In this study, we retrospectively assessed the safety of MMR vaccination (Priorix®, GlaxoSmithKline, Belgium) in patients with HEA hospitalised at our clinic. Detailed medical histories were collected, along with skin prick tests and measurements of specific IgE against milk and egg proteins or extracts. The study included 39 patients with a mean age of 19 months, of whom 15 had previously experienced an anaphylactic reaction after egg ingestion. Results: None of these patients experienced a systemic reaction to vaccination. One patient developed a generalised maculopapular rash, which resolved after a single dose of an antihistamine. Vaccination was postponed in 63% of patients, with the longest delay extending to 113 months. Conclusions: Severe adverse reactions following MMR vaccination in patients with HEA are generally rare and are outweighed by the risks associated with natural infection and its complications. Effective communication of vaccine safety data and strengthening public trust in healthcare professionals are crucial.