27 Jul COVID-19: Safety of Second Dose of mRNA Vaccines After Initial Dose Allergic Reaction

MedicalResearch.com Interview with:

Dr. Blumenthal

Kimberly G. Blumenthal, MD, MSc
Massachusetts General Hospital
The Mongan Institute
Boston, MA 02114

Dr. Krantz

Matthew S. Krantz, MD
Division of Allergy, Pulmonary and Critical Care Medicine
Department of Medicine,
Vanderbilt University Medical Center,
Nashville, Tennessee

MedicalResearch.com: What is the background for this study?

Response: During the initial COVID-19 vaccine campaign with healthcare workers in December 2020, there was an unexpected higher than anticipated rate of immediate allergic reactions after Pfizer and Moderna mRNA vaccines.  This prompted both patient and provider concerns, particularly in those with underlying allergic histories, on the associated risks for immediate allergic reactions with the mRNA vaccines.

Because of the significantly improved effectiveness of two doses of an mRNA vaccine compared to one dose, it was important to determine if those who experienced immediate allergic reaction symptoms after their first dose could go on to tolerate a second dose safely.   

MedicalResearch.com: What are the main findings?

Response: Overall, our study demonstrates that an immediate allergic reaction symptoms, such as flushing, itching, or hives which were most commonly reported, are not contraindications to a second dose of an mRNA vaccine and that most patients after an evaluation by allergist can go on to safely tolerate a second dose without symptoms or those that are mild and managed with antihistamines alone.

MedicalResearch.com: What should readers take away from your report?

Response: Our take home message is that immediate allergic symptoms after mRNA vaccines from Pfizer or Moderna do not preclude their future use.  We were able to oversee the safe complete vaccination of 159 individuals who had reactions with their first mRNA dose.  Complete 2 dose vaccination has become even more important with the Delta variant, and we suspect there are many more people who did not get their second shot because of allergic symptoms.  It is important to discuss this with your doctor and consider allergist input. 

MedicalResearch.com: What recommendations do you have for future research as a result of this work?

Response: We hope to see future research into the mechanisms that underlie these immediate allergic reaction symptoms to mRNA vaccines and risk factors that may predispose patients to these reactions.  Because we did not observe more severe and recurrent reactions in all patients, we suspect that many of the reactions may be from non-IgE mechanisms, which is a different allergic mechanism than peanut allergy, for example, which is an IgE-mediated mechanism.

Citation:

Krantz MS, Kwah JH, Stone CA, et al. Safety Evaluation of the Second Dose of Messenger RNA COVID-19 Vaccines in Patients With Immediate Reactions to the First Dose. JAMA Intern Med. Published online July 26, 2021. doi:10.1001/jamainternmed.2021.3779

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Last Updated on July 27, 2021 by Marie Benz MD FAAD