The Safety of Administering a Second Dose of a COVID-19 mRNA Vaccine in Individuals Who Experienced a Systemic Allergic Reaction to an Initial Dose
Public ClinicalTrials.gov record NCT04977479. Field values are reproduced from the official study page; the official ClinicalTrials.gov record remains the source of truth for eligibility, enrollment, and contact information.
Data is sourced from official ClinicalTrials.gov public API records. Always review the official ClinicalTrials.gov record for the latest information.
Official title
A Randomized, Placebo-controlled Crossover Study to Assess the Safety of Administering a Second Dose of a COVID-19 mRNA Vaccine in Individuals Who Experienced a Systemic Allergic Reaction to an Initial Dose
Study identification
- NCT ID
- NCT04977479
- Recruitment status
- Completed
- Study type
- Interventional
- Phase
- Phase 2
- Lead sponsor
- National Institute of Allergy and Infectious Diseases (NIAID)
- NIH
- Enrollment
- 20 participants
Conditions and interventions
Conditions
Interventions
- Pfizer-BioNTech COVID-19 Vaccine (Comirnaty) Biological
- Placebo Other
- Pfizer-BioNTech COVID-19 Vaccine, Bivalent Biological
Biological · Other
Eligibility (public fields only)
- Age range
- 16 Years to 69 Years
- Sex
- All
- Healthy volunteers
- Healthy volunteers not accepted
This page does not interpret eligibility. Detailed inclusion and exclusion criteria are on the official ClinicalTrials.gov record.
Study timeline
- Start date
- Sep 7, 2021
- Primary completion
- Jun 16, 2022
- Completion
- Feb 21, 2023
- Last update posted
- Oct 15, 2023
2021 – 2023
United States locations
- U.S. sites
- 1
- U.S. states
- 1
- U.S. cities
- 1
| Facility | City | State | ZIP | Site status |
|---|---|---|---|---|
| National Institutes of Health Clinical Center | Bethesda | Maryland | 20892 | — |
Site contact phone numbers, emails, and investigator names are intentionally not displayed here. Open the official ClinicalTrials.gov record for site contact information.
About this trial record page
- What this page shows
- Public field values for ClinicalTrials.gov record NCT04977479, including study identification, conditions, interventions, eligibility (age, sex, healthy volunteer), timeline, and U.S. site list.
- What this page does not do
- No medical advice, eligibility judgments, treatment recommendations, study quality scoring, or AI-generated medical summaries. No site contact phone numbers, emails, or investigator names.
- Where the data comes from
- Sourced from the official ClinicalTrials.gov public API. The official record is the source of truth.
- Last refresh
- Last update posted Oct 15, 2023 · Synced Jul 22, 2026
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Open the official record
The complete protocol, eligibility criteria, and contact information for NCT04977479 live on ClinicalTrials.gov.