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On Jan. 18, Santa Clara County announced it would pause administration of lot 41L20A of Moderna’s COVID-19 vaccine due to the risk of potential allergic reactions. Photo by Lance Cpl. Alex Fairchild/Wikimedia Commons.

UPDATE: Health providers can now resume the administration of lot 41L20A of the Moderna vaccine following a “rigorous review” by safety regulators, Santa Clara County leaders said Thursday.

A specific lot of the Moderna vaccine for COVID-19 has potentially caused a “higher-than-usual” number of allergic reactions but luckily, none of those doses have been administered to anyone in Santa Clara County, county officials said Monday.

The California Department of Public Health on Sunday recommended providers halt the administration of Moderna lot 41L20A because it led to a “higher-than-usual” number of allergic reactions potentially caused by the vaccine, state officials said.

The federal Centers for Disease Control and Prevention reported that anaphylaxis, or extreme allergic reaction, is possible from a COVID-19 vaccine, but less data exists on adverse reactions to the Moderna vaccine.

“A similar vaccine shows that the expected rate of anaphylaxis is approximately 1 in 100,000,” the state’s Department of Public Health said in a statement.

State Epidemiologist Dr. Erica Pan said pausing vaccination from this lot is “out of an extreme abundance of caution,” and “fewer than 10 individuals required medical attention over the span of 24 hours.”

More than 33,000 doses from this lot were distributed across the state, 21,800 of which were allocated to Santa Clara County’s Public Health Department for distribution to local vaccine providers.

Shipments arrived between Jan. 5 through Jan. 12, state officials said in a statement.

County officials said they have notified providers who have received doses from this lot, including Santa Clara Valley Medical Center, Stanford Health Care and El Camino Health.

Vaccine providers are required to report any adverse reactions to the federal government through the Vaccine Adverse Event Reporting System, and county officials said they have not seen “unusual levels of adverse reactions,” in Santa Clara County.

The allergic reactions are under investigation by the CDC, U.S. Food and Drug Administration, Moderna and the state.

“The County is working closely with CDPH as the situation evolves and will notify the affected vaccine providers and the public as soon as more information becomes available,” county public health officials said in a statement.

Find comprehensive coverage on the Midpeninsula’s response to the new coronavirus by Palo Alto Online, the Mountain View Voice and the Almanac here.

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2 Comments

  1. The benefit of administering these 33,000 doses greatly outweighs the risks of allergy. People are dying everyday because of lack of vaccine. What can be worse than that??

  2. What exactly are the allergic reactions residents are experiencing? In San Diego, over the weekend this was highlighted as a potential problem. How many residents took the vaccine without any reaction? People are dying and the government is more concerned about allergic reactions. We should know the percentages of the potential problem. This vaccine may be a problem, but residents should be aware of the exact numbers and percentages.
    Tell that to someone who may die because someone else has an allergic reaction. Instead of the normal buzz words that really don’t tell us anything the government needs to be more honest with residents. The flu vaccine can also cause problems but most residents are receptive to taking the vaccine. The flu vaccine is only 65% effective and some people also report getting reactions after the flu vaccine. I would like the government to get us exact feedback residents are getting instead of the normal words “—– reaction”. I recently asked the health department if they had any proof salons were responsible for the transmission of the virus and got a response that really didn’t answer my question.

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