Most responding to COVID-19 vaccine mRNA tolerate the second dose

HealthDay News – Most patients with an immediate and potentially allergic reaction to the first dose of the Pfizer BioNTech or Moderna mRNA COVID-19 vaccine tolerate a second dose, according to a research letter posted online July 26 in JAMA Internal Medicine was published.

Matthew S. Krantz, MD, of Vanderbilt University Medical Center in Nashville, Tennessee, and colleagues evaluated the safety of the second dose of the Pfizer BioNTech or Moderna vaccine in patients with a history of immediate and potentially allergic reactions to the first dose. Data from 189 participants with first-dose responses to the mRNA COVID-19 vaccine were included: 130 for Moderna and 59 for Pfizer-BioNTech; 32 of these reactions met the anaphylaxis criteria. One hundred and fifty-nine of these participants received a second dose.

The researchers found that 47 of the patients (30 percent) received antihistamine premedication before the second dose. All 159 patients tolerated the second dose, including 19 with anaphylaxis of the first dose. 32 of the patients (20 percent) reported immediate and potentially allergic symptoms associated with the second dose; these were self-limiting, mild, and / or resolved with antihistamines alone.

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“The tolerance of the second dose after reactions to the first dose argues that either many of these initial reactions are not all truly allergic reactions or support an allergic but not immunoglobulin E-mediated mechanism in which symptoms can typically be relieved with premedications” , the authors write.

One author announced financial ties to the pharmaceutical and medical technology industries.

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COVID19 COVID19 Vaccine General Infectious Diseases General Medicine

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