Response by Shah et al to Letter Regarding Article, "Cell-Free DNA to Detect Heart Allograft Acute Rejection". Issue 10 (8th September 2021) - Shah, Palak; Agbor-Enoh, Sean; Tunc, Ilker; Hsu, Steven; Russell, Stuart; Feller, Erika; Shah, Keyur; Rodrigo, Maria E.; Najjar, Samer S.; Kong, Hyesik; Pirooznia, Mehdi; Fideli, Ulgen; et al.