Anaphylaxis accounted for at least 15 percent of the adverse effects reported by clinicians after mRNA vaccinations for COVID-19, according to a late-breaking abstract at the American Academy of Allergy, Asthma & Immunology Annual Meeting. Anaphylaxis appeared more common following vaccination with Pfizer-BioNTech and among white women. Although most of these patients received emergency treatment, few required hospitalisation and none were treated in the ICU, results showed.