Severe allergic reactions to the Moderna COVID-19 vaccine are rare – about 1 in 400,000 recipients suffers from anaphylaxis after receiving the shot, according to the Centers for Disease Control and Prevention.
Ten people – all women – experienced the potentially fatal allergic reaction after receiving their first dose of the injection, with nine cases reported within 15 minutes of vaccination.
That statistic was of the more than 4 million doses administered between December 21 and January 10, and equates to 2.5 cases per million doses given, or 1 case per 400,000 doses, the agency said.
Nine of those who became ill had a history of allergies or allergic reactions, including five with a history of anaphylaxis.
Of the eight people with available follow-up information, all were recovered or fired.
No anaphylaxis-related deaths were reported.
More women than men received the first dose of Moderna – which could explain the unusual finding that all 10 patients who had an anaphylactic reaction were women, the CDC explained.
The reaction requires immediate treatment, usually an injection of epinephrine. If left untreated, it can be deadly.
A total of 1,266 patients who received their first dose of Moderna experienced “side effects,” such as a rash or difficulty breathing, the agency said.
In December, a health worker in Alaska was hospitalized after receiving the Pfizer / BioNTech coronavirus vaccine and experiencing an anaphylactic reaction – which has also been reported in the UK.
“There is a strong female predominance in the cases of anaphylaxis for both vaccines,” the CDC noted in its Friday report.
“Finally, many people who developed anaphylaxis after receiving one of the vaccines had a history of allergies or allergic reactions, and some of them have had anaphylaxis in the past.”