In the latest pitfall of California’s COVID-19 vaccine rollout, the state’s top epidemiologist recommended Sunday night that clinics put hundreds of thousands of doses on hold after a series of allergic reactions in Southern California.
An abnormally high number of people experienced anaphylactic shock, a severe allergic reaction that requires immediate medical attention, after receiving a shot of the Moderna vaccine at one San Diego vaccination site, Dr. Erica Pan said in statement Sunday night. While the number was fewer than 10, the cluster of negative reactions prompted the California Department of Public Health to pause the administration of some 330,000 doses from the batch, which had been distributed throughout the state, until an investigation was complete.
“Our goal is to provide the COVID vaccine safely, swiftly and equitably,” Pan said in the statement. “A higher-than-usual number of possible allergic reactions were reported with a specific lot of Moderna vaccine administered at one community vaccination clinic. … Out of an extreme abundance of caution and also recognizing the extremely limited supply of vaccine, we are recommending that providers use other available vaccine inventory and pause the administration of vaccines from Moderna Lot 041L20A until the investigation by the CDC, FDA, Moderna and the state is complete. We will provide an update as we learn more.”
The 330,000 doses in the batch from Moderna amount to just below 10% of all the vaccine doses allocated to California thus far. But of the 3.5 million doses the state has received, according to data from the Centers for Disease Control and Prevention, it has administered fewer than one-third of those, just over 1 million doses. On a per-capita basis, only five states have delivered fewer shots into arms than California, according to the CDC data.
The reactions reported at the San Diego clinic were similar to rare occurrences that the CDC had warned of and cautioned to be on the lookout for. In California, vaccination sites monitor recipients on-site for 15 minutes for adverse reactions. The cluster in Southern California was the first in the nation concerning enough to pause usage altogether.
Severe allergic reactions, while possible, are believed to be exceedingly rare in the Moderna and Pfizer vaccines. The rate of anaphylaxis in the Moderna vaccine was expected to be about one in every 100,000, officials said. Multiple federal and state agencies had opened an investigation into the cases and said they would have more information later this week.