SAN FRANCISCO, Calif. (KRON) — The Centers for Disease Control and Prevention released data on allergic reactions to COVID-19 vaccines.

Anaphylaxis is a severe, life-threatening allergic reaction that has occurred for some people after receiving the first dose of both the Moderna and Pfizer COVID-19 vaccines.

The CDC says the allergic reaction occurs rarely after vaccination.

Twenty-one cases of Anaphylaxis were detected from Dec. 14 through Dec. 23, 2020 by the Vaccine Adverse Event Reporting System of a reported 1,893,360 first doses of the Pfizer vaccine — that’s 11.1 cases per million doses.

And 71% cases occurred within 15 minutes of receiving the vaccination.

For the Moderna vaccine, the same system detected 10 cases of Anaphylaxis after administering a reporter 4,041,396 doses of the vaccine — which is 2.5 cases per million doses given.

Nine of the 10 cases occurred within 15 minutes of receiving the vaccine.

Fortunately, no Anaphylaxis-related deaths have been reported.