US health officials closely monitoring the potential side effects of the first authorized COVID-19 vaccine said Saturday they’ve seen at least six cases of serious allergic reactions from more than a quarter of a million injections given – prompting a hospital in Illinois to interrupt.
Medical experts said a chemical called polyethylene glycol (PEG), a compound most commonly used in laxatives, could be “the culprit” causing the reactions.
PEG is an ingredient in the Pfizer vaccine, as well as the Moderna Inc vaccine approved Friday.
But the Food and Drug Administration has said that most Americans with allergies should be safe to receive the vaccine. It said only people who have previously had severe allergic reactions to vaccines or ingredients in this particular vaccine should avoid the injection.

A primary care health worker at the Garfield Medical Center will receive his first dose of Pfizer COVID-19 vaccine in a pop-up tent outside their main facility in Monterey Park, California, on Friday.


The Centers for Disease Control and Prevention said it has seen at least six cases of serious allergic reactions to the COVID-19 vaccine developed by Pfizer and BioNTech. Vials of the vaccine are on display above Friday in Pinellas Park, Florida
The Centers for Disease Control and Prevention said more than 272,000 injections of the Pfizer vaccine have been given across the country as of Saturday morning.
Half a dozen cases of allergic reaction were reported as of Friday evening, and included one person with a history of vaccination reactions.
An Illinois medical facility temporarily halted COVID-19 vaccinations after four health workers experienced adverse reactions to the shots.
Advocate Condell Medical Center in Libertyville stopped vaccinations on Friday and will resume on Sunday.
The unidentified workers experienced reactions such as tingling and increased heart rate a few moments after taking the vaccine, ABC 7 reports.
“These four team members represent less than 0.15% of the approximately 3,000 who have received vaccinations to date from Advocate Aurora Health,” a statement read.
While three of the staff recover at home, a fourth receive additional treatment.
Advocate shared it would use the time to help determine what might have triggered the reactions.
The vaccinations are still taking place at the eight other locations of Advocate Aurora Health in Illinois and at the three locations in Wisconsin.


Advocate Condell Medical Center in Libertyville, Illinois, discontinued vaccinations on Friday and will resume on Sunday after four medical workers reported side effects
Three health workers in Alaska needed medical treatment after receiving the vaccine earlier this week, while a hospital in a Chicago suburb halted vaccinations after four staff reported side effects.
Health officials are keeping a close eye on such side effects.
Recipients of US vaccines are supposed to hang around after their injections in case signs of an allergy appear.
The CDC said all cases occurred within the recommended observation window and were treated immediately.
The numbers were discussed at a meeting of a committee that advises the CDC on vaccines.
The group approved Moderna’s COVID-19 vaccine on Saturday, which received an emergency permit on Friday.
Less serious side effects are also rare.
Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, said at a press conference that allergic reactions to PEG are slightly more common than previously believed.
Of the first 215,000 people vaccinated in the United States, less than 1.5 percent had problems that prevented them from performing their normal activities or needing medical attention.


Medical experts said a chemical called polyethylene glycol (PEG), a compound most commonly used in laxatives, could be ‘the culprit’ causing the reactions
Many vaccines can cause temporary discomfort, such as a sore arm or certain flu-like symptoms.
COVID-19 vaccines usually cause more of those reactions than a flu shot, and some hospitals are increasingly getting their workers vaccinated to avoid staff problems.
A doctor in Fairbanks, Alaska, suffered anaphylactic symptoms after receiving the Pfizer coronavirus vaccine, a hospital said Friday, becoming the third health worker in the state to receive an adverse reaction to the new drug.
The doctor, whose name was not released, began showing symptoms about 10 minutes after he was vaccinated on Thursday, according to Foundation Health Partners, operator of Fairbanks Memorial Hospital.
The health worker was treated with epinephrine in the hospital emergency room and released about six hours later, Foundation Health Partners said in a written statement.
Two health workers in Juneau suffered side effects to the medication earlier this week.


One was briefly hospitalized in that city for anaphylaxis after being vaccinated on Tuesday.
The second responded more mildly on Wednesday and was treated and released in the hospital emergency room.
“Allergic reactions, while uncommon, can occur with injections of drugs and vaccines,” said Dr. Angelique Ramirez, Foundation Health Partners Chief Medical Officer in the statement.
The Fairbanks physician has issued her own statement which is included in the Foundation Health Partners release.
“ I would get the vaccine and recommend it to everyone, despite my response, to help immunize our country, which is necessary for the health of all Americans, for the economy, to get families back to hug, to get kids back to school , and to bring the country on the other side of this pandemic, ”the health worker said.
Alaska received its first shipments of the Pfizer vaccine Sunday night, state officials said.
Batches have been sent through the state, including by seaplane and boat to more remote locations.












The cases in Alaska were comparable to two cases reported in Britain last week.
The UK medical regulator has said that anyone with a history of anaphylaxis or severe allergic reactions to a drug or food should not receive the Pfizer-BioNTech COVID-19 vaccine.
On Friday, the FDA said that the Moderna vaccine should not be given to individuals with a known history of serious allergic reactions to any part of the injection.
The regulator also requires that appropriate medical treatments for immediate allergic reactions must be available when the injection is administered in the event of an anaphylactic reaction.
Pfizer was not immediately available for comment.