coronavirus vaccine in the country this week.Addressing a press conference, Dr Peter Marks, the director of the FDA's Center for Biologics Evaluation and Research, said that the allergic reactions had been reported in more than one state, including Alaska.Peter Marks further added that a chemical called polyethylene glycol (PEG) that is an ingredient in the Pfizer Covid-19 vaccine - as well as the Moderna vaccine authorised on Friday - "could be the culprit" causing the reactions.He said that allergic reactions to PEG could be somewhat more common than previously understood.An Alaskan health worker had a serious allergic reaction after getting Pfizer and BioNTech's vaccine.