JW TAN1, GY CHAN1, XR LIM1, JF HOU1, LL XIE1, HL GOH1, SSM LEE1, BY THONG1
Tan Tock Seng Hospital1
Singapore’s Coronavirus disease 2019 (COVID-19) vaccination programme started in December 2020. According to Ministry of Health (MOH) recommendations, patients with allergic reactions to other vaccines should be referred to allergist for further review on suitability to proceed with mRNA-based COVID-19 vaccines. We review the evaluation of these patients with suspected vaccine allergies prior to receiving mRNA-based COVID-19 vaccines.
132 patients were evaluated at the Tan Tock Seng Hospital Vaccine Allergy Clinic between 8 April and 1 Jul 2021. 36 patients consented to participate in the COVID-19 vaccine hypersensitivity registry and their clinical notes were reviewed. Data collected included patient demographics, details of vaccine allergic reaction, allergy evaluation and outcomes.
There were 36 patients recruited, 16 (44.5%) males and 20 (55.5%) females. Influenza (36%) and tetanus (30%) were the most frequent vaccine allergies seen. 7 patients (19%) had large local reactions to a vaccine. Acute vaccine reactions were seen in 15 (42%) patients and delayed reactions in 11 (30%). 3 patients (8%) were found to be not allergic to vaccines.
Skin testing was done for 23 (64%) of the patients referred. Of these patients, 14 with negative skin tests underwent COVID 19 vaccine challenge and tolerated. 9 patients with negative skin tests are awaiting vaccine challenge. Direct Pfizer mRNA COVID 19 vaccine challenge was performed for 12 patients with no reactions observed. One patient is awaiting direct COVID 19 vaccine challenge.
Patients with prior vaccine allergies can safely receive mRNA COVID 19 vaccine under allergist’s supervision.