Less than a third with allergic reaction to the first dose of COVID vaccine have one after the second injection

Less than a third of patients who experience an allergic reaction to their first dose of COVID-19 vaccine have one after the second injection — and symptoms resolve with over-the-counter drugs, study results

  • Patients who developed a severe allergic reaction to the first dose of vaccine can safely go back for a second dose, study finds
  • Over 80% of those who experienced a severe reaction to the vaccine came back for the second dose
  • Less than a third of those people experienced a response to the second dose, although their response was very minor and easily remedied
  • Experts recommend completing vaccine series so that a person can be fully vaccinated against COVID

It’s safe for people who have had an allergic reaction to the first dose of a COVID-19 vaccine to receive the second dose, a new study suggests.

Massachusetts General Hospital (MGH) researchers examined hospital records of people who reported allergic reactions to the first injection of Pfizer or Moderna.

They found that only a third of patients had an allergic reaction to the second dose after receiving one to the first, and the reactions were relatively minor.

The findings add to the growing knowledge about the vaccines and their potential effects on humans over time.

Receiving a second dose of the COVID-19 vaccine is also particularly important, as some studies show that just one dose of a vaccine may not be effective against the Indian ‘Delta’ variant.

Researchers found that people who developed an allergic reaction to the first dose of a COVID-19 vaccine can safely receive the second dose

For the study, published in JAMA Internal Medicine, the team examined data from patients who went to an allergy specialist after receiving their first dose for a potentially life-threatening whole-body allergic reaction.

About 2.5 in 10,000 people, or 0.025 percent, will experience this kind of reaction from the shot.

‘These reactions can be symptoms such as itching or hives or flushing. The patients included were all advised by allergy specialists after their dose one response,” Dr Matthew Krantz, co-lead author and allergy immunology fellow at Vanderbilt University, said in a statement.

Of the 189 patients vaccinated between January 1 and March 31, a total of 159 — or 84 percent — still received the second dose of the vaccine.

Among that group, 32 patients (20 percent) reported allergic symptoms with the second dose.

However, the reactions were relatively minor and resolved with antihistamines.

“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,” said Dr. Kimberly Blumentha, co-author and director of the Clinical Epidemiology Program within the Department of Rheumatology, Allergy and Immunology of MGH.

‘In classic allergy, re-exposure to the allergen causes the same or even worse symptoms.’

Of the group that experienced reactions, 130 (69 percent) received the Moderna injections and 31 percent the Pfizer-BioNTech vaccine.

The most common first-dose reactions recorded were erythema (28 percent of people) — where a person develops a rash — dizziness (26 percent), tingling (24 percent), throat tightness (22 percent), and hives (21 percent).

Researchers recommend that people with an allergic reaction get the second dose anyway, but talk to their allergy specialist first.

Experts recommend that everyone complete their vaccine series — two doses for the Pfizer-BioNTech and Moderna vaccines and one for the Johnson & Johnson vaccine — whenever possible.

Completing a vaccine series produces more antibodies for a person and offers higher efficacy in preventing complications from the virus.

Some studies show that just one dose of a vaccine even makes a person vulnerable to the Delta strain, a highly contagious strain of virus that is rampant across the country.

The variant is good for about 70 percent of active cases in the United States.

Currently, about 56 percent of Americans have received one dose of a COVID-19 vaccine and just under 50 percent are fully vaccinated.

Any American age 12 or older is eligible for a COVID-19 vaccine.

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