People Who Had Allergic Reactions to First COVID-19 mRNA Vaccine Dose Tolerate Second Dose Without Complications

Allergists encourage patients to complete their vaccination course.

Second COVID-19 mRNA vaccine dose found safe after allergic reactions to the first dose.

In a multi-hospital analysis of individuals who experienced an allergic reaction to their first mRNA COVID-19 vaccine dose, all patients who received a second dose tolerated it without complications. The study, led by allergists at Massachusetts General Hospital (MGH) and published in JAMA Internal Medicine, indicates that a first dose response to COVID-19 vaccination should not prevent people from getting a second dose.

Allergic reactions to mRNA COVID-19 vaccinations have been reported as high as 2%, with anaphylaxis – a life-threatening whole-body allergic reaction – occurring in up to 2.5 per 10,000 people. To investigate whether it is safe to proceed with a second mRNA COVID-19 vaccine dose after a dose one response, researchers from MGH, Vanderbilt University Medical Center, University of Texas Southwestern Medical Center and Yale School of Medicine combined patient data who sought allergy specialist care in their hospitals after a reaction to their first mRNA COVID-19 vaccine dose. “These reactions can include symptoms such as itching or hives or flushing. The admitted patients were all advised by allergy specialists after their dose of one reaction,” explains co-lead author Matthew S. Krantz, MD, of Vanderbilt University Medical Center.

Of the 189 patients, 32 (17%) experienced anaphylaxis after their first dose of mRNA COVID-19 vaccine. A total of 159 patients (84%) received a second dose. All 159 patients, including 19 subjects who experienced anaphylaxis after the first dose, tolerated the second dose. Thirty-two patients (20%) reported immediate and possibly allergic symptoms associated with the second dose that were self-limiting, mild and/or resolved with antihistamines alone.

“A key point from this study is that these immediate-onset mRNA vaccine responses may not be mechanically induced by classical allergy, termed immediate hypersensitivity or Ig-E mediated hypersensitivity. For classic allergy, re-exposure to the allergen produces the same or even worse symptoms,” said co-senior author Kimberly G. Blumenthal, MD, MSc, co-director of the Clinical Epidemiology Program within MGH’s Division of Rheumatology, Allergy and Immunology. .

The study’s findings suggest that it is safe for most people to receive a second dose of the mRNA COVID-19 vaccine, notes co-senior author Aleena Banerji, MD, clinical director of the Allergy and Clinical Immunology Unit. at MGH. “After reactions to the first dose, allergy specialists can be helpful to guide risk-benefit assessments and help complete safe vaccination,” she says.

Reference: July 26, 2021, JAMA Internal Medicine.
DOI: 10.1001/jamainternmed.2021.3779

This study was funded by the National Institutes of Health and MGH.