Immediate hypersensitivity reaction to COVID-19 vaccines: What's the value of skin tests?

ABSTRACT

Background: Most of adverse reactions (ARs) caused by COVID-19 vaccines are self-limited and benign, such as localized cutaneous injection-site reactions, fatigue, headache. However, IgE-mediated hypersensitivity reactions (HSR) to COVID-19 vaccines are considered extremely rare. These HSR are either attributed to the vaccine itself or its excipients. Method(s) We carried out a retrospective study including all cases of suspected immediate HSR induced by COVID-19 vaccination and notified to the pharmacovigilance department of Monastir (Tunisia). Skin tests (Prick and intradermal tests (IDR)) to vaccines and their respective excipients were performed. Result(s) Among 339 ARs following COVID-19 vaccination, only 10 cases were related to suspected immediate HSR (7 females/3 males) with an average age of 46 years old. Clinical manifestations were urticaria in 7 cases, anaphylactic reaction grade 3 in 2 cases and grade 2 in one case. The median delay to the onset of symptoms was 3 hours (few seconds to 24 hours). All immediate HSR were secondary to the first dose of vaccine administration. Suspected Covid-19 vaccines were Vaxzevria in 6 cases, Moderna in 2 cases, COMIRNATY and CoronaVac in one case, each of them. Skin tests (Prick test/ IDR10-1/ undiluted IDR) were performed for all patients. Only 2 patients, who presented urticaria and anaphylactic 0.0shock, had a positive result to the culprit vaccine Vaxzevria. Skin test (Prick test/IDR10-1) to the excipient (Polysorbate 80) was negative. Among patients with negative skin tests (n = 8), six underwent vaccination with the same vaccine with antihistaminic premedication, without recurrence of the HSR. In the two remaining patients, culprit vaccines were contraindicated in view of the severity of the reaction Conclusion(s) Hypersensitivity reactions to COVID-19 vaccines are unpredictable and can vary from a localized reaction to life-threatening anaphylaxis. Skin tests can be helpful in the diagnosis of authentic IgE mediated HSR. However, their sensitivity remains to be determined in a large scale population.