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
Brief summary
Reproduced verbatim from the official ClinicalTrials.gov record. Not medical advice.
Background: Some people have allergic reactions to COVID-19 mRNA vaccines. Researchers want to learn more about these reactions to provide guidance on who can safely receive the vaccines, including a second dose in people who had a reaction to the first. Objective: To study the safety of giving a second mRNA COVID-19 vaccine dose to people who had a systemic allergic reaction to their first dose. Eligibility: People aged 16-69 who had a systemic allergic reaction to their first dose of COVID-19 vaccine. Design: Individuals who have underlying health issues may need to come to the NIH for screening tests to make sure they are safe to receive the vaccine. People who are eligible to participate in the study will be admitted to the NIH hospital and stay for at least 4 days. They will give urine samples. They will have a nasal swab SARS-CoV-2 test. They will have an intravenous line placed in each arm. They will get the study vaccine (Pfizer-BioNTech COVID-19 vaccine) and one dose of placebo on different days. They will have breathing tests. They may have clinical photography if they develop a rash. Participants will have 4 follow-up visits - 2 by phone and 2 in-person visits at the NIH campus . They will have allergy skin testing at one visit. Drops of different allergens or controls will be placed on their back or arm. The skin under each drop will be scratched with a tool. If the results are negative, a small amount of allergen will be injected just below the surface of their skin. Participants who have no or only a mild allergic reaction to the second dose of the vaccine may be eligible to receive a Booster dose at the NIH. Participation will last for approximately 5 months.
Study identification
- NCT ID
- NCT04977479
- Recruitment status
- Completed
- Study type
- Interventional
- Phase
- Phase 2
- 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 Sep 5, 2026
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Open the official record
The complete protocol, eligibility criteria, and contact information for NCT04977479 live on ClinicalTrials.gov.