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.