The doses administered to the six healthcare workers were part of the Moderna Lot 041L20A distributed to 287 providers across the state earlier this month. That batch of shipment, which arrived in California between Jan. 5 and Jan. 12, is composed of 330,000 shots.
Moderna said in a statement that it is cooperating with California's health department to investigate the allergic reactions.
"Moderna acknowledges receiving a report from the California Department of Public Health (CDPH) 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," the statement read. "The company is fully cooperating with CDPH in investigating these reported adverse events."
Dr. Erica Pan, California’s state epidemiologist, said Sunday, Jan. 17, that providers should err on the side of caution and stop using the doses until federal, state and company officials finish an investigation.
"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 Centers for Disease Control and Prevention (CDC), Food and Drug Administration (FDA), Moderna and the state is complete," she said.
Monterey, Santa Clara and Santa Cruz have already paused distribution while two Covid-19 vaccine clinics have been canceled in Stanislaus County following the allergic reaction reports.
The delay was a huge blow to California's vaccine distribution efforts. California currently has the second highest number of coronavirus cases per capita in the United States, with Los Angeles being a particular hotspot.
All cases of apparent allergic reactions occurred at San Diego County’s drive-through mass vaccination site at Petco Park. No other providers have reported allergic reactions to vaccines administered from the same batch of doses. Related: Shock video: Woman suffers convulsions following Covid vaccine.)
Operations at Petco Park slowed down after the cases of allergic reactions were reported, said Dr. Eric McDonald, San Diego County’s director of epidemiology. He noted that the health providers swapped out the batch of vaccines they were administering.
The Vaccination Super Station at Petco Park has the capacity to administer 5,000 shots per day. It’s one of several mega-sites launched in California last week. There’s a similar clinic at Dodger Stadium that will soon have a capacity of about 12,000 shots daily, according to city officials.
Several people reportedly experienced anaphylactic shock after receiving their first vaccine dose. Anaphylactic shock is a severe and potentially life-threatening reaction to an allergy from food, medicine or even a type of material. Symptoms usually occur within minutes and include hives, a weak pulse, nausea, vomiting, dizziness and a swollen tongue or throat.
It can lead to death if not treated immediately. People suffering from it are normally given epinephrine, a hormone that relaxes the airway muscles, to treat their symptoms.
One of the six healthcare workers who suffered allergic reaction was Diana Cannizzo. She said she couldn't feel her tongue and had neck pain after being given the shot.
"They gave me 50 milliliters of Benadryl and then they started monitoring me even closer," she told NBC 7 San Diego.
Cannizzo admitted that she had some underlying conditions from other medications.
"I don't know if that came into play. Maybe it did, maybe it didn't but anybody that has a lot of allergic reactions, just maybe think about it and talk to their doctors," she said.
All sites giving coronavirus vaccines have specific guidelines to follow, including monitoring of patients after the shot is administered for at least 15 minutes – or longer in cases where patients have a medical condition that could lead to an allergic reaction.
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