Bottom line: The risk is less with the Moderna vaccine than with Pfizer.
Anaphylaxis is a severe, potentially life-threatening allergic reaction. It can occur within seconds or minutes of exposure to something you’re allergic to, such as peanuts or bee stings.
Anaphylaxis causes your immune system to release a flood of chemicals that can cause you to go into shock — your blood pressure drops suddenly and your airways narrow, blocking breathing. Signs and symptoms include a rapid, weak pulse; a skin rash; and nausea and vomiting. Common triggers include certain foods, some medications, insect venom and latex.
Anaphylaxis requires an injection of epinephrine and a follow-up trip to an emergency room. If you don’t have epinephrine, you need to go to an emergency room immediately. If anaphylaxis isn’t treated right away, it can be fatal.
When the first Covid 19 vaccine from Pfizer was released there was concern about the rate of anaphylaxis related to the vaccine which was higher that with other vaccines. Here’s the information from Morbidity and Mortality Weekly.
Weekly / January 15, 2021 / 70(2);46–51
On January 6, 2021, this report was posted online as an MMWR Early Release.
CDC COVID-19 Response Team; Food and Drug Administration (View author affiliations)
Summary
What is already known about this topic?
Anaphylaxis is a severe, life-threatening allergic reaction that occurs rarely after vaccination.
What is added by this report?
During December 14–23, 2020, monitoring by the Vaccine Adverse Event Reporting System detected 21 cases of anaphylaxis after administration of a reported 1,893,360 first doses of the Pfizer-BioNTech COVID-19 vaccine (11.1 cases per million doses); 71% of these occurred within 15 minutes of vaccination.
What are the implications for public health practice?
Locations administering COVID-19 vaccines should adhere to CDC guidance for use of COVID-19 vaccines, including screening recipients for contraindications and precautions, having the necessary supplies available to manage anaphylaxis, implementing the recommended postvaccination observation periods, and immediately treating suspected cases of anaphylaxis with intramuscular injection of epinephrine.
And this is the latest on the Moderna vaccine:
Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Moderna COVID-19 Vaccine — United States, December 21, 2020–January 10, 2021
Early Release / January 22, 2021 / 70
CDC COVID-19 Response Team; Food and Drug Administration (View author affiliations)
Summary
What is already known about this topic?
Anaphylaxis is a severe, life-threatening allergic reaction that occurs rarely after vaccination.
What is added by this report?
During December 21, 2020–January 10, 2021, monitoring by the Vaccine Adverse Event Reporting System detected 10 cases of anaphylaxis after administration of a reported 4,041,396 first doses of Moderna COVID-19 vaccine (2.5 cases per million doses administered). In nine cases, onset occurred within 15 minutes of vaccination. No anaphylaxis-related deaths were reported.
What are the implications for public health practice?
Locations administering COVID-19 vaccines should adhere to CDC guidance, including screening recipients for contraindications and precautions, having necessary supplies and staff members available to manage anaphylaxis, implementing recommended postvaccination observation periods, and immediately treating suspected anaphylaxis with intramuscular epinephrine injection.
In a person with severe reactions to vaccines or a history of anaphlyaxis, it might be preferable to use the Moderna vaccine versus the Pfizer if there is an option, but precautions still need to be taken.
