The US Food and Drug Administration is investigating five allergic reactions to the Pfizer Inc and BioNTech SE's COVID-19 vaccine in the United States this week.
Dr. Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said at a press conference that the allergic reactions had been reported in multiple states including Alaska.
Marks also said that a chemical called polyethylene glycol that is an ingredient in the Pfizer vaccine - as well as the Moderna Inc vaccine authorized on Friday - 'could be the culprit' causing the reactions.
Marks said that allergic reactions to PEG could be somewhat more common than previously understood.
The US Food and Drug Administration is investigating five allergic reactions to the Pfizer Inc and BioNTech SE's COVID-19 vaccine in the United States this week
The reactions include a Fairbanks, Alaska, clinician, whose name was not released, that started showing symptoms about 10 minutes after being inoculated on Thursday, according to Foundation Health Partners, operator of the Fairbanks Memorial Hospital.
The health care worker was treated in the hospital´s emergency room with epinephrine and released about six hours later, Foundation Health Partners said in a written statement.
Two health care workers in Juneau suffered adverse reactions to the medication earlier this week. One was briefly hospitalized in that city for anaphylaxis after she was vaccinated on Tuesday. The second had a milder reaction on Wednesday and was treated at the hospital emergency room and released.
The Fairbanks clinician issued her own statement that was included in the Foundation Health Partners release.
'I would get the vaccine and recommend it to anyone, despite my reaction, to help our country get immunized which is needed for the health of all Americans, for the economy, get families hugging again, for getting children back to schools, and to get the country on the other side of this pandemic,' the health worker said.
Medical assistant Vangie Yazzie administers the Pfizer COVID-19 vaccine to Galena Dineyazhe as director of nursing Monica Jones (back right) watches at the Dr. Guy Gorman Senior Care Home on the Navajo Nation in Chinle, Ariz. on December 18
Two others who received the vaccine in the US also suffered allergic reactions this week.
The cases in Alaska were similar to two cases reported last week in Britain.
Britain's medical regulator has said that anyone with a history of anaphylaxis, or severe allergic reactions to a medicine or food, should not be given the Pfizer-BioNTech COVID-19 vaccine.
But the U.S. 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 getting the shot.
On Friday, the FDA said the Moderna vaccine should not be given to individuals with a known history of a severe allergic reactions to any components of the shot.
The regulator is also requiring that appropriate medical treatments for immediate allergic reactions must be available when the shot is administered in case of an anaphylactic reaction.
Pfizer could not be immediately reached for comment.
Pfizer vaccine side effects
British regulators are advising that anyone who has a history of 'significant' allergic reactions to medicines, food or vaccines should not get the Pfizer coronavirus jab.
Allergic reactions to the vaccine are 'very rare', according to the trials involving more than 40,000 people.
Pfizer found a 'very small number' during its phase three clinical studies, or 137 out of 19,000 people who got the vaccine. But 111 people who were given a placebo also had allergic reactions.
They also identified 12 possible side-effects from the vaccine, with seven identified as 'very common' meaning they are likely to affect more than one in ten people. Below are the known side effects.
The patient safety leaflet for the vaccine cautions that anyone with an allergy to any of the active substances in the vaccine should not receive the jab.
Allergic reactions to the vaccine are:
Very common (Likely to affect more than one in ten people)
Common (Likely to affect up to one in ten people)
Uncommon (May affect one in 100 people)