Respiratory syncytial virus in hematopoietic cell transplant recipients and patients with hematologic malignancies

Khawaja, Fareed; Chemaly, Roy F.

There are limited data on HCT recipients and pulmonary function (including changes in FEV 1 and oxygen diffusion capacity) after an RSV infection. Avetisyan et al. showed that, compared to a control group, HCT recipients with RSV infections were more likely to develop mild or marked changes in vital capacity or diffusion capacity during pulmonary function tests. 24 Subsequently, Seo et al. described significant decreases in patients' diffusion capacity 3 months after RSV infection, which persisted for a year. 43 There were some indications that FEV 1 and total lung capacity were also affected, but the sample size was too small to draw definite conclusions. Another study compared the effects of different viruses on pulmonary function in HCT recipients; 60 RSV and parainfluenza were associated with FEV 1 decreases of at least 10%. It was postulated that subclinical shedding of these viruses may augment airway inflammation, leading to airway restriction. In comparison, lung transplant recipients who are infected with respiratory viruses are at increased of risk of developing bronchiolitis obliterans, with an associated mortality of up to 29%. 65 Similarly, HCT recipients with prior respiratory viral infections were more likely to develop bronchiolitis obliterans or changes in FEV 1 , 59,66 with a higher mortality rate than that of patients without bronchiolitis obliterans (HR: 2.7). 59 Delayed or failed engraftment of stem cells during or after acute RSV infection has been reported; however, it is an uncommon complication with a total of only seven patients having been described in a few case series. 45, 46, 62 This association was first described in 1999 by McCarthy et al., who noted that four patients with graft failure had had an RSV infection in the pre-engraftment period, 45 with no other identified infections. Furthermore, during an RSV outbreak in a hematologic unit in Australia, delayed neutrophil and platelet engraftment occurred in two autologous HCT recipients and graft failure occurred in one allogeneic HCT recipient with an RSV infection. 62 On the other hand, a study by Waghmare et al. showed no significant changes in lymphocyte count dynamics in HCT recipients who experienced progression to RSV LRTI compared to patients who did not. 46 Overall, there are very limited data supporting that RSV infection per se leads to graft failure or contributes to a delay in engraftment.