Wisconsin COVID-19 Vaccine Program

Potential for Anaphylaxis Following COVID-19 Vaccination

Anaphylaxis is a severe, life-threatening allergic reaction that occurs rarely after vaccination, with onset typically within minutes to hours.

As of January 19, monitoring by the Vaccine Adverse Event Reporting System (VAERS) on COVID-19 vaccine administration detected:

• 47 cases of anaphylaxis after administration of the Pfizer COVID-19 vaccine (4.7 cases per million doses administered)
• 19 cases of anaphylaxis after administration of Moderna COVID-19 vaccine (2.5 cases per million doses administered)

These estimated rates may change as additional doses of COVID-19 vaccine are administered. The data available to date show that anaphylaxis is a rare occurrence following COVID-19 vaccination. As stated in a recent MMWR, this data "is within the range reported after receipt of inactivated influenza vaccine (1.4 per million), pneumococcal polysaccharide vaccine (2.5 per million), and live attenuated herpes zoster vaccine (9.6 per million)." Symptoms of anaphylaxis typically occur within 30 minutes of vaccine administration and are more likely to occur in individuals with a history of allergies or prior allergic reactions.

COVID-19 Vaccinators Should Continue to do the Following:

• Screen recipients for contraindications and precautions prior to vaccination and ensure you are using the most recent screening tool for COVID-19 vaccine. 
• Have necessary supplies and staff to manage anaphylaxis and immediately treat suspected anaphylaxis with intramuscular epinephrine injection.
• Implement recommended post-vaccination observation periods; 30 minutes for persons with a precaution to COVID-19 vaccination or with a history of anaphylaxis due to any cause and 15 minutes for all other recipients.
• See additional clinical considerations.

Adverse Event Monitoring

Report to VAERS any:

• Vaccine administration error whether or not associated with an adverse event
• Serious adverse events** (irrespective of attribution to vaccination)
• Cases of Multisystem Inflammatory Syndrome (MIS) in adults and children
• Cases of COVID-19 that result in hospitalization or death

**Serious adverse events are defined as:

• Death;
• A life-threatening adverse event;
• Inpatient hospitalization or prolongation of existing hospitalization;
• A persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions;
• A congenital anomaly or birth defect;
• An important medical event that based on appropriate medical judgement may jeopardize the individual and may require medical or surgical intervention to prevent one of the outcomes listed above.

Other Adverse Event Reporting to VAERS

Vaccinators may report to VAERS other adverse events that are not required to be reported.

Please do not reply directly to this email message. If you have a question, please email DHSCOVIDVaccinator@wi.gov.