LOS ANGELES - The U.S. Centers for Disease Control and Prevention says that out of more than 4 million of the first administered doses of the Moderna COVID-19 vaccine, only 10 cases of anaphylaxis — a rare, life-threatening allergic reaction — have occurred.
Using the CDC’s Vaccine Adverse Event Reporting System, the health agency said it detected the 10 cases of the severe reaction after administering 4,041,396 doses of the Moderna coronavirus vaccine. In nine cases, onset of the anaphylactic reaction occurred within 15 minutes of vaccination.
No anaphylaxis-related deaths have been reported in anyone who has taken the COVID-19 vaccine, according to the CDC.
On Wednesday, California, the state hardest hit by the novel coronavirus, said it was safe to immediately begin using a batch of coronavirus vaccine doses after health officials urged a halt to injections and held a review because several people had severe reactions.
A pharmacy technician prepares a dose of the COVID-19 Pfizer vaccine to be administered to a patient at Harbor-UCLA Medical Center amid a surge of coronavirus patients on January 21, 2021 in Torrance, California.
The California Department of Public Health on Sunday urged a pause in the use of a specific lot of the Moderna virus after fewer than 10 people who received shots at a San Diego vaccination site needed medical care, possibly due to rare but severe allergic reactions.
But after a safety review and consultation with Moderna and health agencies, the state "found no scientific basis to continue the pause" and said vaccinations can "immediately resume," state epidemiologist Dr. Erica Pan said in a statement.
California on Monday became the first state to record more than 3 million known coronavirus infections.
The CDC has previously said COVID-19 vaccines can cause side effects for a few days that include fever, chills, headache, swelling or tiredness, "which are normal signs that your body is building protection."
However, severe reactions are extremely rare. Pan said in a vaccine similar to Moderna's, the rate of anaphylaxis — in which an immune system reaction can block breathing and cause blood pressure to drop — was about 1 in 100,000.
The Associated Press contributed to this report