USF Health’s Dr. Thomas Casale leads one of only two academic allergy-research centers in Florida participating in the national trial

TAMPA, Fla. (April 14, 2021) — USF Health is participating in a National Institutes of Health (NIH) clinical trial to determine whether highly allergic people or those with mast cell disorders are at greater risk for severe, immediate allergic reactions to the Moderna or Pfizer-BioNTech COVID vaccines.  A mast cell disorder is caused by a type of white blood cell that is abnormal, overly active or both, predisposing a person to life-threatening reactions that resemble allergic reactions.

USF Health allergist Thomas Casale, MD, is the USF site principal investigator for the Systemic Allergic Reactions to SARS-CoV-2 Vaccination clinical trial, sponsored by the National Institute of Allergy, Immunology and Infectious Diseases, part of NIH. | Photo by Torie Doll

The USF Health Asthma, Allergy and Immunology Clinical Research Unit is one of only two academic allergy-research centers in the state, and up to 35 centers nationwide, enrolling adults who have not yet received a COVID vaccine in this Phase 2 randomized, placebo-controlled trial funded by NIH’s National Institute of Allergy and Infectious Diseases (NIAID). The USF site will enroll 120 participants, ages 18 to 69, in the study; two-thirds must have a history of severe allergic reactions or diagnosis of a mast cell disorder, and one-third must have no history of allergies. Nationwide, 3,400 adults are expected to complete the 17-week NIAID trial called Systemic Allergic Reactions to SARS-CoV-2 Vaccination.

The Moderna and Pfizer-BioNTech COVID-19 vaccines were the first two COVID-19 vaccines authorized by the Food and Drug Administration for emergency use and have already been given to millions of Americans.

Rare, severe allergic reactions to both messenger RNA (mRNA) COVID vaccines have occurred more commonly in women and primarily in people with a history of allergies to foods, insect bites, or medications. A large number had previously experienced anaphylaxis, a potentially life-threatening allergic reaction with serious symptoms, such as  hives, swelling, low blood pressure, difficulty breathing and severe diarrhea. Reversing anaphylaxis requires treatment with autoinjectible epinephrine, and/or an emergency room visit.

“Defining the causes of acute allergic reactions to these two mRNA vaccines will be critical to enhance safety of potentially required booster mRNA vaccinations, or different mRNA vaccine platforms, used for COVID or other infectious diseases,” said USF site principal investigator Thomas Casale, MD, a professor of medicine and pediatrics in the Division of Allergy and Immunology, USF Health Morsani College of Medicine.

Severe allergic reactions to the two mRNA COVID-19 vaccines  — made by Pfizner-BioNtech and by Moderna  — have been rare, but higher than incidences reported for other vaccines in general. | Photo by Allison Long

Anaphylaxis has been reported at a rate of about 10 to 12 people per every 1 million Pfizer-BioNTech COVID-19 vaccine doses administered, and 2.5 per 1 million Moderna vaccine doses,

“These incidences have been rare, but still higher than what we see with typical vaccines, such as those for influenza; measles, mumps and rubella; tetanus; and hepatitis. With vaccines in general, severe allergic reactions occur at a rate of about 1.3 people per 1 million injections,” Dr. Casale said. “I would emphasize that nothing contained in these two mRNA COVID vaccines has yet been identified as the culprit triggering the allergic reactions reported.”

Study participants will be divided into groups and assigned at random to receive either the Pfizer-BioNTech vaccine (one-third), the Moderna vaccine (one-third), a placebo followed by the Pfizer-BioNTech vaccine (one sixth); or a placebo followed by the Moderna vaccine (one sixth). Initially, neither the participants nor the study team will know who receives a vaccine or the placebo, or which vaccine is being administered. All participants ultimately will receive a full two-dose course of either the Pfizer-BioNTech vaccine or the Moderna vaccine.

The Centers for Disease Control and Prevention currently recommends a 30-minute on-site observation period after COVID-19 vaccination for people with any history of severe or sudden allergic reactions. Those in the NIAID trial will be closely monitored for at least 90 minutes after each injection by allergists trained to recognize and treat anaphylaxis, and armed with emergency medications, oxygen, and medical equipment.

“It’s important to allay some of the vaccine hesitancy concerns among this higher-risk population,” Dr. Casale said. “We’re vaccinating people in a very controlled environment. So, if anyone does experience an acute allergic reaction, we’re right there to immediately treat them and get them safely through it.”

Investigators will assess the proportion of study participants in each group who have a severe allergic reaction within 90 minutes after injection with the first or second doses of either the Pfizer-BioNTech vaccine or the Moderna vaccine. Results are expected in late summer 2021.

The USF Health Asthma, Allergy and Immunology Clinical Research Unit stocks stocks auto-injectable epinephrine that can be quickly administered to counteract severe and immediate allergic reactions. | Photo by Torie Doll

If a significant number of severe allergic reactions to either or both mRNA COVID vaccines occur during the trial, researchers will analyze blood and urine samples collected before and after each injection to identify possible biological mechanisms for the reactions. They will examine whether certain genetic patterns or other factors can predict which individuals are most susceptible to adverse effects, Dr. Casale said.

For more information on the clinical trial, or to speak to a USF Health coordinator, please call 813-631-4024.