Hill JA, Vusse LKV, Xie H, et al. - Given that bronchoalveolar lavage fluid (BALF) from immunocompromised people with lower respiratory tract disease (LRTD) commonly contain human herpesvirus 6B (HHV-6B) DNA, researchers investigated if HHV-6B represents a pulmonary pathogen. Participants were allogeneic hematopoietic cell transplantation (HCT) recipients. These individuals underwent a BAL for assessment of LRTD from 1992 to 2015. Evidence demonstrating a link between HHV-6B detection in BALF and higher mortality in allogeneic HCT recipients with LRTD was generated in this study. A nearly 1 log₁₀ lower median HHV-6B BALF viral load, as well as a lower risk of overall mortality, were observed in individuals with HHV-6B⁺ BALF who took antivirals within 3 days pre-BAL vs those with HHV-6B⁺ BALF not receiving antivirals. A randomized prevention or treatment trial will be needed for definitive evidence of causation.