No Correlation between Anti-PF4 and Anti–SARS-CoV-2 Antibodies after ChAdOx1 nCoV-19 Vaccination

This correspondence investigates the potential immunological link between SARS-CoV-2 vaccination and vaccine-induced immune thrombotic thrombocytopenia (VITT), focusing on antibody responses. Researchers assessed 101 vaccinated healthy controls and 59 patients with suspected VITT after receiving the ChAdOx1 nCoV-19 vaccine. Antibody levels against SARS-CoV-2 proteins (spike trimer, RBD, S1, S2, nucleocapsid) and anti–platelet factor 4 (PF4) antibodies were measured. Among patients, 20 were confirmed to have VITT via PF4 ELISA and platelet aggregation assays. The study found no meaningful correlation between anti-PF4 antibodies and anti–SARS-CoV-2 antibody levels, suggesting no immunogenic cross-reactivity between these antibody groups. These findings challenge hypotheses about SARS-CoV-2 spike protein triggering VITT through PF4 mimicry.

This correspondence investigates the potential immunological link between SARS-CoV-2 vaccination and vaccine-induced immune thrombotic thrombocytopenia (VITT), focusing on antibody responses. Researchers assessed 101 vaccinated healthy controls and 59 patients with suspected VITT after receiving the ChAdOx1 nCoV-19 vaccine. Antibody levels against SARS-CoV-2 proteins (spike trimer, RBD, S1, S2, nucleocapsid) and anti–platelet factor 4 (PF4) antibodies were measured. Among patients, 20 were confirmed to have VITT via PF4 ELISA and platelet aggregation assays. The study found no meaningful correlation between anti-PF4 antibodies and anti–SARS-CoV-2 antibody levels, suggesting no immunogenic cross-reactivity between these antibody groups. These findings challenge hypotheses about SARS-CoV-2 spike protein triggering VITT through PF4 mimicry.