COVID-19 revaccination following allergic reaction safe with diagnostic workup

Revaccination among patients with suspected allergic reactions to the COVID-19 vaccine appeared safe after diagnostic workup to assess for drug excipient allergy, according to data published in Clinical and Translational Allergy.

The researchers from the Odense Research Centre for Anaphylaxis at Odense University Hospital in Denmark gathered data on 61 patients (women, n = 54; age range, 18-88 years) who previously experienced an allergic reaction to the COVID-19 vaccine.

Of these patients, 30 received the Pfizer-BioNTech vaccine, six received the Moderna vaccine and 25 received the AstraZeneca vaccine. Fifty-five of the patients had a reaction to the first vaccine dose and underwent evaluation before receiving the second dose.

Nine patients experienced anaphylaxis according to the Brighton criteria. Other reactions included asthma attacks or skin symptoms such as flushing. Patients also reported symptoms including discomfort, sensation of throat tightness, shortness of breath and nausea.

Patients in the cohort had received an average of 1.6 virus-based vaccines during the last 5 years with no history of allergic reactions related to the vaccines.

Researchers evaluated the patients with skin prick test and basophil histamine release testing with COVID-19 vaccines and relevant drug excipients, with 55 patients testing negative and six patients testing positive.

The researchers successfully revaccinated 52 of the 55 patients who experienced an adverse reaction after their first dose of the COVID-19 vaccine without any occurrence of allergic symptoms or signs. This included seven of the eight patients who met Brighton level 2 or 3 for anaphylaxis. One patient who met Brighton level 1 was referred after their second vaccination.

Reasons for not revaccinating the other three patients included positive SPT to all excipients (n = 1) or patient decision to abstain from second vaccination (n = 2).

Patients who had received the AstraZeneca vaccine, which had been excluded from the Danish vaccination program, were successfully revaccinated with either the Pfizer-BioNTech vaccine (n = 19) or Moderna vaccine (n = 4).

“In a large population-based study, vaccines are generally thought to induce anaphylaxis at a rate of 1.31 cases per million doses,” the researchers wrote, adding that in this study, the one case of Brighton level 1 anaphylaxis was “only possibly linked to the Pfizer-BioNTech vaccine,” as the reaction happened 40 hours after vaccination and in combination with the intake of a nonsteroidal anti-inflammatory drug.

“This indicates that the incidence of anaphylactic reactions to COVID‐19 vaccines is compatible to findings with other vaccines,” the researchers wrote. “The low rate of anaphylaxis may be facilitated by the fact that our citizens with the highest probability of developing severe reactions (patients with mastocytosis, patients with known reactions to drug excipients and patients with prior reactions to other vaccines) were evaluated — and in some cases COVID‐19 vaccinated — in our center.”