The CDC released data Friday that suggests severe allergic reactions to the Moderna COVID-19 vaccine appear rare.

Out of more than 4 million shots given, there were 10 instances of a severe allergic reaction, or anaphylaxis, reported.

All of the cases were treated with epinephrine and none of them resulted in death.

Another commonality is that all of the cases involved women.

“[That] has to be taken in the context that two-thirds of the people vaccinated so far are women,” explains Dr. Manish Ramesh, Assistant Professor of Allergy and Immunology at Montefiore Medical Center. “And it happens to be because healthcare workers were first in line for vaccination and a majority of healthcare workers, especially nurses, are women and that may account for the female predominance seen in this data.”

Providers administering the vaccines are required to be prepared for the rare instance of a severe allergic reaction because it can be a life threatening situation.

Dr. Matthew Harris, medical director of the Northwell Community Vaccination Program, explained if there is an anaphylactic reaction, the data shows it happens on average about 7.5 minutes after the vaccine. Medical professionals are trained to keep people with a history of allergic reactions under supervision for at least 30 minutes after the shot, so they can immediately respond, he said.

“So the good news is that the mechanism that we have to keep people safe is working,” Dr. Harris said.

Doctors encourage people with a history of severe reactions to consult medical professionals before getting the vaccine.

The Moderna data, showing a severe reaction at a rate of about 2.5 per million doses follows the CDC’s report from earlier in the month that severe allergic reactions to the Pfizer/Biontech vaccine occur at a rate of about 11 per million vaccinations.

“My understanding is that this is relatively comparable to the Pfizer data,” said Dr. Harris. “It is extraordinarily rare. This is a safe vaccine. I think we can feel confident we are not endangering anyone. Rather, quite the opposite. By taking this vaccine, you are ensuring the health of yourself and your community.”