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ST. LOUIS – Phase 1A of the COVID-19 vaccination rollout continues in Missouri, with frontline health care workers the first to receive the initial rollout. As more shots are given, there has been concern regarding allergic reactions to the drug.

There is one ingredient being investigated for causing uncommon allergic reactions in the Pfizer and Moderna vaccines.

“The likely suspect of causing issues is called Polyethylene Glycol or PEG for short,” Dr. Jennifer Monroy, Washington University allergist and immunologist at Barnes-Jewish Hospital, said.

PEG is a preservative used to help protect the vaccine. This ingredient commonly used.

“It’s found in a lot of preparations that we use on a day-to-day basis,” Monroy said. “It is found in processed foods, it is found in our cosmetics, and it is found in other medications.”

Miralax is one medication that uses the drug.

Most people with this uncommon sensitivity to PEG are likely to have a history.

Monroy said 71% of reactions occur within 15 minutes of the shot.

CDC guidelines recommend patients stay at the provider 15 minutes after receiving their dose.

As with most vaccines, allergic reactions are uncommon. Side effects are common and expected.

“This is going to differ from people, you know, going home the next day and feeling more run down, feeling aches, feeling sores, having a fever,” Monroy said. “Those are going to be more delayed responses that are not going to have you preclude you from getting the vaccine in the future. It’s a reassuring symptom that your body is immunizing this vaccine and creating a response to it.”

Even the doctor experiencing it for herself.

“I got the vaccine a week ago,” Monroy said. “And it felt for me very typical that you are getting the flu vaccine, that later in the evening I just had some soreness in my arms and I just took a couple of Ibuprofen and I was fine the next day.”

It is unclear which vaccination, the Pfizer or Moderna, is causing more allergic reactions.
They both contain the PEG drug.

More research and data is being gathered at this time.