Allergic reactions at one San Diego site led state to shelf 330,000 vaccine doses.
By Catherine Ho
A cluster of allergic reactions that prompted California to halt the use of hundreds of thousands of doses of coronavirus vaccine has thrown another wrench into the state’s struggling vaccination rollout, forcing some health care providers to cancel clinics on Monday.
The development stems from one batch of Moderna vaccines apparently linked to severe allergic reactions in six health care workers who received shots at a mass vaccination site at Petco Park, the Padres’ baseball stadium in San Diego last week. The California Department of Public Health on Sunday issued a statement recommending that health care providers stop using vaccines from this batch, which arrived in California between Jan. 5 and Jan. 12.
More than 330,000 doses from this batch, or lot, were sent to 287 providers across the state, including some in the Bay Area. The doses, which expire in July, will not be thrown out. They will be kept in storage until public health and Moderna officials who are investigating the cases know more about what caused the allergic reactions. The state hopes to provide more information this week.
“It’s probably prudent to hold them, but every time a vaccine isn’t given out, it’s slowing us down,” said Dr. Monica Gandhi, an infectious disease physician at UCSF.
As of Sunday, about 43% of the 3.2 million doses shipped to local health departments and providers statewide had been administered.
Some doses from the Moderna lot have already been administered, but statewide, it is unclear exactly how many and where. No other clusters of allergic reactions have been reported from sites that used vaccines from the same lot, the state said Sunday.
On Monday, two vaccination clinics — Stanislaus County’s in Modesto and one at CSU Stanislaus — canceled appointments because they could no longer guarantee vaccine availability due to the Moderna issue.
In the Bay Area, health care providers in San Francisco, Alameda, Marin and Santa Clara counties are among those that received doses from this batch. Providers that had started using those doses have stopped.
Kaiser Permanente has removed doses of the Moderna batch from its vaccine supply, a Kaiser spokesman said Monday. No severe reactions were recorded in Kaiser members who got the vaccine. Kaiser did not say how many doses from the batch it received or how many it administered. “This situation only affects a relatively small percentage of our supply,” the spokesman said.
Marin County received about 1,200 doses from the batch on Jan. 11 and had administered all of them by Friday; no one reported allergic reactions. Santa Clara County was allocated 21,800 doses from the batch to distribute to providers, but none have been administered.
San Francisco, which received about 8,000 doses from the batch, had administered some but stopped using those doses on Friday when it heard about the problems in San Diego. The city reported no adverse reactions to the doses that had already been given.
The San Francisco Department of Public Health has not had to cancel appointments yet and is trying to complete vaccinations that are already scheduled. But it may become difficult by the end of the week unless additional doses arrive.
“This setback comes at a time when vaccine is scarce and when SFDPH allocation from the state arriving this week is only 1,775,” a department spokeswoman said. “This will have an impact on the overall city’s ability to complete scheduled appointments.”
The six cases of allergic reaction at the Petco Park vaccination site occurred in a 24-hour span and required medical care. It is unclear what symptoms the individuals had or whether any of them have a history of allergic reactions. The Food and Drug Administration has said there is a remote chance that the Moderna and Pfizer vaccines can cause allergic reactions including difficulty breathing, rash and swelling of the face and throat.
Authorities have not said whether the six people have anything in common beyond having received shots at the same vaccination site last week. The San Diego County Health and Human Services Agency referred questions to the state and the FDA. The state said it does not have any information about whether the six individuals have a history of allergic reactions. The FDA did not immediately respond to questions Monday.
“That number, clustered together, was slightly higher than expected for the time period,” Dr. Eric McDonald, San Diego County’s director of epidemiology, said about the Petco Park allergic reactions last week. He said the batch was swapped out “in the possible event” the reactions were connected.
The allergic reactions appeared to happen within the observation period required after receiving the vaccine. Because of early reports of a small number of people experiencing severe allergic reactions, regulators recommend that people who get the vaccine be observed for 30 minutes afterward.
Moderna said Monday it is cooperating with the state health department to investigate the reported reactions. The company said it is not aware of comparable adverse events from other vaccination sites that may have administered doses from the same batch.
“Moderna acknowledges receiving a report from the California Department of Public Health that a number of individuals at one vaccination center were treated for possible allergic reactions after vaccination from one lot of Moderna’s COVID-19 vaccine,” a Moderna spokeswoman said in a statement Monday. “The company is fully cooperating with CDPH in investigating these reported adverse events.”
The U.S. Centers for Disease Control and Prevention and the FDA are also reviewing the batch.
The state said the risk of a serious adverse reaction is very small. It is unclear how many cases of severe allergic reaction have occurred in people after getting the Moderna vaccine.
For a similar vaccine, made by Pfizer, the risk is less than 1 in 100,000. There were 175 cases of possible severe allergic reactions, including 21 cases of anaphylaxis, identified out of nearly 1.9 million doses administered in the United States as of Dec. 23, according to the CDC.
Each batch of vaccine may have slightly different amounts of certain ingredients, which could be why this one batch was linked to a cluster of severe reactions, vaccine experts said. It is possible, for instance, that one batch contains slightly more polyethylene glycol, or PEG, an ingredient that the National Institutes of Health has been looking into as a potential cause of earlier reports of anaphylaxis in a small number of people who got the Pfizer vaccine.
PEG has not been used before in other vaccines, but is used in the coronavirus vaccines to keep the fragile genetic material they rely on stable.
“Every batch is not like a batch of shoes (that) all look alike, maybe this batch had more PEG in it, or a different ingredient,” Gandhi said. “It may have had a little too much X and too little of this. It could just be associated with one batch.”