Successful fractionated undiluted doses of COVID-19 vaccine in five cases of suspected allergic reactions to the first dose.

After a suspected allergic reaction to first dose of mRNA COVID-19 vaccine, given the PEG skin tests negativity and tolerance in vivo to PEG containing drugs, five patients were vaccinated with the second dose of Pfizer-Biontech undergoing a fractional protocol, with antihistamine premedication, without presenting immediate or delayed reactions.