Impact of COVID-19 after lung transplantation: A retrospective multicenter comparison of clinical outcomes in Denmark and Sweden

Background

The coronavirus disease-2019 (COVID-19) pandemic posed pronounced challenges in the care of lung transplant (LTx) recipients. Global variations in containment strategies and the introduction of messenger ribonucleic acid (mRNA) vaccines have sparked extensive debate in both scientific and public arenas.

Methods

This retrospective study compared outcomes among LTx recipients in Denmark, which implemented a more restrictive COVID-19 containment strategy, and Sweden, which adopted a less restrictive approach. A total of 318 LTx recipients with at least 1 episode of polymerase chain reaction (PCR)-confirmed COVID-19 were included. Propensity score weighting was applied to balance covariates, and survival outcomes were analyzed using weighted Cox proportional hazards and Kaplan-Meier analyses.

Results

No significant differences in mortality or risk of chronic lung allograft dysfunction (CLAD) were found between countries (hazard ratios [HR] for death, Sweden = 1.49, 95% confidence intervals [CI]: 0.68-3.26, p = 0.314; HR for CLAD, Sweden = 0.63, 95% CI: 0.32-1.25, p = 0.187). Unvaccinated patients had a significantly higher risk of death compared to vaccinated patients (HR = 3.49, 95% CI: 1.46-8.34, p = 0.005), and infections with the original Wuhan strain carried a higher risk than Omicron (HR = 3.59, 95% CI: 1.53-8.44, p = 0.003). CLAD development or progression was not significantly associated with any subgroup.

Conclusions

Despite differences in timing of infections and case load between Sweden and Denmark, clinical outcomes among infected LTx recipients were comparable. mRNA vaccination was strongly associated with improved survival. The results of the current study highlight the importance of continued vaccination efforts and tailored containment strategies in vulnerable populations.