Broad Decline in Viral Infections During COVID-19 Lockdown: Association with Lung Function in Lung Transplant Recipients

Purpose In April 2020 COVID-19 lockdown measures were instigated leading to a dramatic drop in non-COVID respiratory virus infections (RVI). This provided a unique situation to assess the impact of RVI on annual FEV1 decline, episodes of temporary drop in lung function suggestive of infection (TDLF) and CLAD in lung transplant recipients (LTR). Methods All lung function tests (LFT) of LTR transplanted between 2009-April 2020 were used from post-transplant baseline onward. LFT were censored after COVID-19 infection. Weekly RVI counts from the virology department defined RVI pressure over time. TDLF was defined as sudden, reversible FEV1 drop compared to previous 4 values (any TDLF ≥10% and ≥200ml, severe TDLF ≥20% and ≥500ml). Annual FEV1 decline was estimated using linear mixed effects models with separate estimates for 2009/20 and 2020/21. Effect modification by TDLF frequency of individual LTR (two subgroups, split at median) and RVI pressure was tested. Rates of CLAD and TDLF were analyzed over time. Results 479 LTR (12,775 LFT) were included. Annual FEV1 change in 2009/20 was -114ml [95%CI -133; -94], while in 2020/21 this was significantly less: 5ml [-38; 48] (p<0.001). RVI pressure significantly affected FEV1 level (an increase in weekly RVI-count of 10 leading to a 7ml [-10; -5] lower FEV1 (p