NIH launches trial to study allergic reactions to COVID-19 mRNA vaccine

Researchers from the National Institute of Allergy and Infectious Diseases (NIAID) are conducting a clinical trial designed to help understand rare, but potentially serious systemic allergic reactions to COVID-19 mRNA vaccines. The single-site trial will enroll up to 100 people aged 16 to 69 years old who had an allergic reaction to the first dose of COVID-19 mRNA vaccines. Study participants will receive a second dose of vaccine as inpatients under carefully controlled conditions at the National Institutes of Health’s Clinical Center in Bethesda, Maryland, NIH notified in a statement.

“People who experienced an allergic reaction after receiving a COVID-19 mRNA vaccine may be hesitant to complete their vaccine regimen,” said Anthony S Fauci, MD, Director, NIAID, in the statement.

He added, “This study will help us determine if individuals who experienced moderate systemic allergic reactions can safely receive a second dose of a COVID-19 mRNA vaccine.”

The trial is seeking participants who experienced a mild or moderate systemic allergic reaction following the first dose of either the Pfizer-BioNTech or the Moderna COVID-19 mRNA vaccine. However, people who developed severe allergic reactions to the first dose of a COVID-19 mRNA vaccine are not eligible to enroll, the statement further added.

“Overall, severe allergic reactions to COVID-19 mRNA vaccines, including life-threatening anaphylaxis reactions such as low blood pressure and difficulty in breathing, are rare, on the order of five cases per million vaccine doses administered. Our study aims to provide a better understanding of the mechanisms responsible for systemic allergic reactions such as hives, swelling, trouble breathing and light-headedness or passing out,” noted Dr Pamela A Guerrerio, MD, PhD, Laboratory of Allergic Diseases, NIAID, in the statement.

To maximise safety, all participants will be admitted for a minimum of four days to the Intensive Care Unit (ICU) at the NIH Clinical Center, where experienced medical staff, as well as equipment and medications needed to treat severe allergic reactions, are readily available. On consecutive days, each participant will be randomly assigned to receive either the FDA-approved Pfizer COVID-19 mRNA vaccine, Comirnaty, or a look-alike dose of inactive placebo. All participants will thus receive the vaccine on one of the two days and can expect to be fully vaccinated by the end of their ICU admission.

At admission and during the inpatient stay, participants will have breathing tests and frequent blood draws, which will be used by medical staff to discern details of any allergic or other responses to the vaccine. The enrollees will also complete mental health/anxiety questionnaires prior to, at the time of, and in the months following vaccination. In addition to a follow-up interview by phone one week after discharge, participants will also be asked to return to the NIH for an in-person follow-up one month and again five months after vaccination. At the five-month visit, all participants who tolerated the second dose of the vaccine with no or only mild symptoms will be offered a booster vaccination with the Comirnaty COVID-19 vaccine, concluded the statement.