Trends in hospitalisations for lower respiratory tract infection after the COVID-19 pandemic in adults with chronic respiratory disease

IntroductionCOVID-19 pandemic has modified the epidemiology of lower respiratory tract infections (LRTI), particularly in patients presenting a chronic respiratory disease (CRD). LRTI incidence substantially decreased at the start of the COVID-19 pandemic. However, studies focusing on the post-pandemic period are missing. We aimed to evaluate the impact of the pandemic and post-pandemic periods on hospital admissions for LRTI, with a focus on patients with CRD. MethodsFrom July 2013 to June 2023, monthly numbers of adult hospitalisations for LRTI (excluding SARS-CoV-2) were extracted from the anonymized French National Hospital Discharge Database. They were modelled by regressions with autocorrelated errors. Three periods were defined: (1) early pandemic and successive lockdowns (April 2020 to May 2021); (2) gradual lifting of restrictions and widespread SARS-CoV-2 vaccination (June 2021 to June 2022); (3) withdrawal of restriction measures (July 2022 to July 2023). Analyses were computed for the entire series, by gender, age, severity, and pre-existing CRD ResultsBefore the pandemic, LRTI hospitalisations showed a winter seasonal pattern with a rising trend. Pre-pandemic incidence was 96 (90.5 to 101.5) per 100,000 population. Compared with the pre-pandemic period, seasonality was no longer present and significant reductions were estimated in the first two periods: -43.64% (-50.11 to -37.17) and -32.97% (-39.88 to -26.05), respectively. A rebound with a positive trend and a seasonal pattern was observed in period 3. Similar results were observed for CRD patients with no significant difference with pre-pandemic levels in the last period (-9.21%; -20.9% to 1.67%), albeit with differential changes according to the type of CRD. ConclusionsCOVID-19 pandemic containment measures contributed to significant changes in LRTI incidence, with a rapid increase and return to a seasonal pattern after their gradual lifting, particularly in patients with CRD.