Timeline of the events. Patient 1 received the first and the second dose of the SARS-CoV-2 vaccine (BNT162b2, Pfizer-BioNTech) in April and May, respectively. In June, he was infused with the PEG conjugates FVIII product turoctocog alfa pegol. Patient 2 received the first and the second dose of the SARS-CoV-2 vaccine (BNT162b2, Pfizer-BioNTech) in October and November, respectively. In December, he was infused with the PEGylated FVIII product damoctocog alfa pegol. A poor FVIII recovery after the PEGylated FVIII infusion was found for both patients. For patient 1, the pre- and postinfusion FVIII activity was <1% and 5%, respectively; for patient 2, the pre- and postinfusion FVIII activity was 4% unchanged.