COVID-19 revaccination shows low risk for repeated immediate, severe allergic reactions
Click Here to Manage Email Alerts
Individuals who had an immediate allergic reaction to a first SARS-CoV-2 mRNA vaccine showed a low risk for an immediate or severe allergic reaction following the second dose, according to results of a systemic review and meta-analysis.
The results, published in JAMA Internal Medicine, suggested revaccination of those who experienced such reactions to a first dose is safe in a supervised setting, according to the researchers.
It had been established prior to this study that the prevalence of immediate severe reactions to the mRNA COVID-19 vaccines was about 7.91 per million doses, according to Matthew Greenhawt, MD, MBA, MSc, director of the food challenge and research unit at Children’s Hospital Colorado and assistant professor of pediatrics at University of Colorado School of Medicine.
“The study was prompted by concerning reports, particularly early in the vaccine rollout, regarding allergic reactions, prompting guidance from health care authorities recommending against giving a second dose to anyone who had an immediate allergic reaction to a first dose,” Greenhawt told Healio. “Such guidance not only contradicts the current allergy practice parameters for vaccine allergy, it also reduces access to a full vaccine series among a subset of the population, potentially unnecessarily.”
To better understand the risk for a second severe allergic reaction after SARS-CoV-2 vaccination, researchers searched MEDLINE, Embase, Web of Science and the WHO global coronavirus database to identify 22 studies that addressed immediate allergic reactions of any severity to a second vaccine dose following an immediate allergic reaction to the first dose. The studies comprised 1,366 individuals (mean age, 46.1 years; 87.8% women) who had an immediate allergic reaction within 4 hours of their first vaccination, which included 78 individuals who had a severe immediate reaction, such as anaphylaxis.
All revaccination attempts used mRNA vaccines and occurred under the guidance of an allergy specialist.
Results of a pooled random-effects model showed that six individuals developed severe immediate allergic reactions after the second dose, for an absolute risk of 0.16% (95% CI, 0.01-2.94). All six of the patients survived, five of whom recovered quickly after receiving intramuscular epinephrine. Four of these severe reactions occurred among the 78 individuals who had a severe allergic reaction to the first dose (absolute risk, 4.94%; 95% CI, 0.93-22.28).
A vast majority (n = 1,360; 99.84%; 95% CI, 97.09-99.99) tolerated the dose, whereas 232 (13.65%; 95% CI, 7.76-22.9) developed mild symptoms, including 15 (9.54%; 95% CI, 2.18-33.34) of those who had severe reactions to the first dose.
The low rate of repeat reactions suggests that the mechanism of COVID-19 vaccine reactions may not be mediated by IgE, Greenhawt said.
“This means there is not a specific IgE antibody against the vaccine or a vaccine component that is causing persons to react, and as a result lowers the risk the event would recur if the individual was revaccinated,” he said. “This is good news, as it suggests that this is not acting like a traditional allergen, as say peanut or penicillin would in a person allergic to that item, where you’d expect a reaction if they were given those items.
“While it remains unclear what triggered the first event, the low rate of recurrence suggests that these individuals can be safely revaccinated under the supervision of a specialist trained in the management of allergic reactions,” Greenhawt said, adding that because these reactions may not be IgE mediated, there also should be low recurrence of reactions with booster doses, although this study predated recommendations for a third dose.
Further, these results persisted in sensitivity and subgroup analyses that accounted for studies that used graded dosing, premedication or skin testing as pre-vaccination risk-stratification measures.
“Among those individuals who have had a possible allergic reaction to the first dose of a COVID-19 vaccine, almost all of them can be safely revaccinated and complete their primary vaccine series in the setting of allergist supervision,” Greenhawt said. “These findings strongly support not contraindicating the vaccine among those with prior allergic reactions. This has the potential to change current practice and further prevent COVID-19 transmission and severe COVID-19 outcomes.”
For more information:
Matthew Greenhawt, MD, MBA, MSc, can be reached at matthew.greenhawt@childrenscolorado.org.