Population-Based Incidence, Severity, and Risk Factors Associated with Treated Acute-Onset COVID-19 mRNA...

Area of Science:

• Immunology
• Vaccinology
• Public Health

Background:

• Acute-onset hypersensitivity reactions to COVID-19 mRNA vaccines can cause public anxiety and contribute to vaccine hesitancy.
• Understanding the incidence, severity, and risk factors of these reactions is crucial for public health initiatives.

Purpose of the Study:

• To determine the incidence, severity, and risk factors for treated acute-onset hypersensitivity reactions following COVID-19 mRNA vaccination.
• To characterize these events in a large, well-defined population.

Main Methods:

• A retrospective analysis of Kaiser Permanente Southern California members who received COVID-19 mRNA vaccinations between December 15, 2020, and March 11, 2021.
• Identification and characterization of all treated acute-onset vaccination-associated hypersensitivity events.

Main Results:

• Out of 391,123 vaccine recipients, treated hypersensitivity events were rare: 0.028% after the first dose and 0.014% after the second dose.
• Anaphylaxis occurred in only 0.00033% of vaccinations.
• Individuals experiencing treated events were more likely to be female, younger, and have a history of drug "allergies".

Conclusions:

• Treated acute-onset hypersensitivity events following COVID-19 mRNA vaccination are generally benign.
• These reactions are more common with the first vaccine dose and occur more frequently in younger females with risk factors for multiple drug intolerance syndrome.
• The events are unlikely to be primarily immunologically mediated.