Early Respiratory Viral Acquisition after Allogeneic Hematopoietic Cell Transplant (HCT)

INTRODUCTION: Respiratory infections after HCT lead to significant morbidity, mortality, and health care costs due to pulmonary complications. In up to a third of patients following allogeneic HCT, infection can progress from an upper to a lower respiratory tract infection. Without vaccines or effective therapeutics for most viruses, very little can be done beyond supportive care. OBJECTIVES: There is a need to identify risk factors for virus acquisition in HCT recipients in order to develop and implement better preventative interventions. METHODS: In a prospective study, 471 HCT patients enrolled between 2005 and 2010 underwent weekly PCR-based surveillance for RSV, metapneumovirus, parainfluenza virus 1-4, influenza A and B, rhinovirus, coronavirus, and adenovirus. Detailed weekly surveys were collected from subjects for up to 1 year post-transplant on symptoms and exposures to children under 10 years or sick contacts (within 3 feet for more than 1 hour total in the past week). We performed multivariable Cox regression analysis to identify risk factors associated with the time to first positive respiratory viral detection by PCR (asymptomatic and symptomatic) within the first 100 days HCT. RESULTS: In this cohort, 211 patients (45%) acquired a respiratory virus in the first 100 days after transplant. Of those infected, 88 (42%) were symptomatic with at least 2 respiratory symptoms. We found significantly higher risk of acquiring any respiratory viral infection for patients with underlying chronic leukemia compared with other hematologic malignancies [hazard ratio (HR) 1.79 (1.16 – 2.77)], exposure to children under or over 4 years [HR 1.84 (1.36 – 2.48)], exposure to contacts with cold symptoms [HR 1.47 (1.02 – 2.12)], exposure to systemic steroids [HR 1.49 (1.07 – 2.08)], and absolute monocyte counts < 100/µL [HR 1.81 (1.12 – 2.94)]. Age, age of child exposure, gender, smoking history, season, conditioning regimen, donor relationship, cell source, presence of acute GVHD, albumin level, total IgG level, lymphocyte counts, and neutrophil counts were not associated with risk for acquisition. We also analyzed the association of these same variables with the time to first positive respiratory viral detection with symptomatic respiratory disease. We found that exposure to children [HR 1.56 (1.03 – 2.35)] and exposure to steroids [HR 1.59 (1.01 – 2.52)] remained associated with acquisition of symptomatic respiratory viral infection. CONCLUSIONS: These data support the contribution of both exposure and immunologic determinants to the risk of respiratory viral acquisition with and without development of symptoms. Although many infections were asymptomatic, patients receiving steroids and those in close proximity to children may benefit from closer monitoring and counseling in the early post-transplant period.