CI

At a glance

ClinicalIndex Comparison Record
Phase 2Completed· 746 enrolled
Drug / intervention
Moderna COVID-19 Vaccine +2 morebiological
Likely dose
Not stated in record
Structured eligibility isn't available for this trial yet — see the full criteria in the Eligibility tab below.

Standardized by ClinicalIndex from the ClinicalTrials.gov record · verify against the source.

Search/NCT04761822
NCT04761822Phase 2Completed

Systemic Allergic Reactions to SARS-CoV-2 Vaccination

National Institute of Allergy and Infectious Diseases (NIAID)·interventional·Posted Feb 21, 2021·Updated Aug 12, 2025

In Brief

A Phase 2 clinical trial evaluating Moderna COVID-19 Vaccine, Pfizer-BioNTech COVID-19 Vaccine, and 1 other intervention for SARS-CoV Infection and 3 related conditions. Completed, enrolled 746 participants across 29 sites.

Detailed Summary

Background: Allergic reactions have been reported to occur after vaccination with both the Pfizer-BioNTech COVID-19 Vaccine and Moderna COVID-19 Vaccine. Allergic reactions range from mild to severe and include life- threatening anaphylactic reactions, although no deaths have been reported with either vaccine. This study is designed with two principal aims: * To estimate the proportions of systemic allergic reactions to the Pfizer-BioNTech COVID-19 Vaccine and the Moderna COVID-19 Vaccine in a High-Allergy/Mast Cell Disorder (HA/MCD) population, and * If the risk in the HA/MCD is demonstrable, to determine whether the proportions are higher in the HA/MCD in comparison to a representative population without severe allergies or mast cell disorders

Study Details

Study Typeinterventional
Allocation--
Masking--
Primary Purpose--
CountriesUnited States

Timeline

Phase 2CompletedFinished
202120222023202420252026
First PostedFeb 21, 2021
Enrollment StartApr 7, 2021
Primary CompletionApr 20, 2022
Study CompletionApr 27, 2022
TodayJul 2, 2026
Enrollment to primary: 1.0 yearsPosted 5.4 years ago

Interventions

Moderna COVID-19 Vaccinebiological

Intramuscular injection

Pfizer-BioNTech COVID-19 Vaccinebiological

Intramuscular injection

Placebobiological

Intramuscular injection