Impact of COVID-19 social distancing measures on lung transplant recipients: decline in overall respiratory virus infections is associated with stabilisation of lung function

BACKGROUND: COVID-19 social distancing measures led to a dramatic decline in non-COVID respiratory virus (RV) infections, providing a unique opportunity to study their impact on annual FEV(1) decline, episodes of temporary drop in lung function (TDLF) suggestive of infection and chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTR). METHODS: All FEV(1) values of LTR transplanted between 2009-April 2020 were included. Annual FEV(1) change was estimated with separate estimates for pre- social distancing (2009/2020) and the year with social distancing measures (2020/2021). Patients were grouped by individual TDLF frequency (frequent/infrequent). RV circulation was derived from weekly hospital-wide RV infection rates. Effect modification by TDLF frequency and RV circulation was assessed. CLAD and TDLF rates were analyzed over time. RESULTS: 479 LTR (12 775 FEV(1) values) were included. Pre- social distancing annual change in FEV(1) was −114 mL [95%CI; −133; −94], while during social distancing FEV(1) did not decline: +5 mL [−38; 48] (difference pre- versus during social distancing: p<0.001). The frequent TDLF subgroup showed faster annual FEV(1) decline compared to infrequent TDLF (−150 mL [−181; −120] versus −90 mL [−115; −65] p=0.003). During social distancing, we found significantly lower odds for any TDLF (OR 0.53 [0.33; 0.85], p=0.008) and severe TDLF (OR 0.34 [0.16; 0.71] p=0.005) as well as lower CLAD incidence (OR 0.53 [0.27; 1.02] p=0.060). Effect modification by RV circulation indicated a significant association between TDLF/CLAD and RVs. CONCLUSION: During social distancing the strong reduction in RV circulation coincided with markedly less FEV(1) decline, fewer TDLFs and possibly less CLAD. Effect modification by RV circulation suggests an important role for RVs in lung function decline in LTR.