Second dose of the COVID-19 vaccine is safe even after initial allergic reaction, study finds

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Experts say the second dose of a vaccine is safe for most consumers

A new study conducted by researchers from Massachusetts General Hospital explored the safety of getting a second dose of an mRNA COVID-19 vaccine following an allergic reaction from the first dose. 

Their findings showed that an allergic reaction from the first dose of a COVID-19 vaccine isn’t likely to yield a poor response to the second dose. Ultimately, the team says it’s important for consumers to get both doses of the vaccine to ensure the most protection from the virus

Safety for the second dose

For the study, the researchers analyzed data from nearly 200 patients who required professional medical help following an allergic reaction from the first dose of a COVID-19 vaccine. 

“These reactions could include symptoms such as itching or hives or flushing,” said researcher Dr. Matthew S. Krantz. “The patients included were all advised by allergy specialists after their dose one reaction.” 

The study showed that nearly 85% of the participants followed through with the second dose of the vaccine, and it was ultimately considered safe -- even for those that experienced anaphylaxis following the first dose. The second dose wasn’t free of allergy-related side effects; the researchers said 20% of the participants reported mild symptoms, though they didn’t require more than an antihistamine to control the reaction. 

Moving forward, the team hopes consumers don’t skip the second round of a COVID-19 vaccine if the first one prompted an allergic reaction. They recommend consulting with medical professionals to cover any questions or concerns prior to receiving the second dose. 

“After first dose reactions, allergy specialists may be useful to help guide risk/benefit assessments and assist with completion of safe vaccination,” said researcher Dr. Aleena Banerji. 

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