Human Metapneumovirus and Parainfluenza Virus Infections in Lung Transplant Recipients: the Effects on Lung Allograft and Clinical Outcomes.

BACKGROUND: Human metapneumovirus (HMPVi) and parainfluenza virus (PIV) infections are common community acquired infection in lung transplant recipients (LTRs), but data is extremely limited. METHODS: A retrospective study including all LTRs at the Johns Hopkins Hospital during July 2010-June 2019 with positive HMPV and PIV polymerase chain reaction (PCR) respiratory specimens was performed. RESULTS: Thirty-one HMPV- and 53 PIV-infected LTRs were identified. LTRs with HMPVi and PIVi had similar baseline characteristics, infection parameters, treatment allocation, and allograft function outcomes. Among entire cohort, 31.6% had CLAD stage progression within 1-year post infections (29.2% vs 35.5% for PIV vs HMPV, respectively, p= 0.56). In forced expiratory volume in 1 second percent (FEV1%) trajectory analysis showed steadily decline of FEV1 across time among CLAD stage progressor from both viruses. FEV1% decline ≥ 10% at 90 days had adjusted hazard ratio for CLAD stage progression of 18.4 [4.98, 67.76] and 4.6 [1.36, 15.34] for PIVi and HMPVi, respectively. PIVi caused higher DSA development (11.8% vs 3.2%, p=0.18) and 1-year mortality (9.4% vs 0%, p=0.11), compared to HMPVi, even though the results were not statistically significant. Ribavirin did not show protective effect and mycophenolate discontinuation during infection did not increase risk of CLAD stage progression. CONCLUSION: One-third of HMPV- and PIV- infected LTRs developed CLAD stage progression within 1 year. The lack of early lung function recovery may predict long term CLAD progression.