VITT after ChAdOx1 nCoV-19 Vaccination

To the Editor: The Journal recently published three studies involving a total of 39 persons in whom vaccine-induced immune thrombotic thrombocytopenia (VITT), a devastating syndrome characterized by thromboses in unusual sites, developed after they received the ChAdOx1 nCoV-19 vaccine. The articles by Schultz et al. and Greinacher et al. (June 3 issue) 1,2 and by Scully et al. (June 10 issue) 3 all conclude that it was highly unlikely that the patients had been previously infected with SARS-CoV-2, since they tested negative for antibodies to the SARS-CoV-2 nucleocapsid protein. I believe that this statement is questionable and probably erroneous. Studies have shown . . .