Virus-specific T cells allow targeting of multiple pathogens in patients after hematopoietic stem cell transplantation and have demonstrated potential efficacy for cytomegalovirus, Epstein-Barr Virus, and adenovirus. Novel targets may include BK virus, JC virus, varicella zoster virus, human herpesvirus 6, Aspergillus, human parainfluenza virus-3, herpes simplex virus Type I, Zika virus, and mycobacteria. Generation of patient-specific products and third-party products may expand feasibility of therapy.