Two days after the first COVID-19 vaccine was administered in the U.S. — to a healthcare worker in Long Island, New York — two healthcare workers in Alaska who received Pfizer’s COVID vaccine experienced allergic reactions. One of those, a woman with no prior history of allergies, suffered an anaphylactic reaction and spent at least two nights in the hospital.

The reactions, similar to those experienced on Dec. 8, shortly after rollout of the same Pfizer vaccine in the UK, raise renewed concerns about the potential for life-threatening reactions to the vaccine. Concerns include the vaccine maker’s exclusion of people with severe allergies from the clinical trials, and the failure to pre-screen patients for polyethylene glycol (PEG), the compound suspected of triggering the reactions, before administering the vaccine.

An initial investigation into the allergic reactions experienced by the two UK healthcare workers identified PEG as the likely trigger for those anaphylactic reactions.

In September, Children’s Health Defense’s chairman and chief legal counsel, Robert F. Kennedy, Jr., warned the FDA about the potential for vaccines containing PEG — an ingredient used in the Pfizer and Moderna vaccines — to cause severe allergic reactions.

On learning Wednesday of the hospitalization of the woman in Alaska, Kennedy said:

“When we warned FDA Director Peter Marks that the nanoparticles in this vaccine pose deadly risks from anaphylaxis, he suggested we take our concerns directly to the vaccine makers. We clearly have a systematic problem when government health regulators have utterly abdicated their responsibility to safeguard public health and refer safety concerns about shoddily tested, zero-liability vaccines to pharmaceutical companies.”

Vaccine makers have zero legal or financial incentive to make their products safe, Kennedy added. “Let’s remember that Pfizer will make billions so long as it keeps its vaccine in play, no matter how many people experience life-threatening reactions,” he said.

A spokeswoman for Pfizer told the Washington Post the company is “actively working with local health authorities to assess” what happened in Alaska. She also told the Post that prospective participants in Pfizer’s late-stage clinical trial were excluded if they had a history of severe allergic reactions associated with a vaccine or to any component of this vaccine.