A Nationwide Cohort Study of Delta and Omicron SARS-CoV-2 Outcomes in Vaccinated Individuals With Chronic Lung Disease

Abstract

BackgroundIndividuals with chronic-lung-disease (CLD) are more susceptible to respiratory viral infections; however, there is significant heterogeneity in the literature on CLD and COVID-19 outcomes. Data is lacking on outcomes with newer variants (eg. Omicron) and in vaccinated/boosted populations. Research QuestionWhat are the outcomes of SARS-CoV-2 infection in individuals with CLD during Delta and Omicron transmission, in a highly vaccinated/boosted population-based cohort? Study Design and MethodsOutcomes of Delta/Omicron SARS-CoV-2 infection in a highly vaccinated/boosted cohort of adult Singaporeans with CLD (including asthma, chronic-obstructive-pulmonary-disease [COPD], bronchiectasis and pulmonary fibrosis) were contrasted against matched population controls. Calendar time-scale Cox regressions were used to compare risk of infection, COVID-19-related hospitalizations and severe COVID-19 disease, adjusting for sociodemographic factors/comorbidities. ResultsOverall, 68,782 individual patients with CLD and 534,364 matched population controls were included. 92.7% of CLD patients were boosted by the end of the Omicron wave. Compared with controls, higher risk of SARS-CoV-2 infection, COVID-19-related hospitalization and severe COVID-19 was observed amongst patients with CLD during both Delta (infection: adjusted-hazards-ratio, aHR=1.22[1.17-1.28]; hospitalization: aHR=1.76[1.61-1.92]; severe-COVID-19: aHR=1.75[1.50-2.05]) and Omicron waves (infection: aHR=1.15[1.14-1.17]; hospitalization: aHR=1.82[1.74-1.91]; severe-COVID-19: aHR=2.39[2.18-2.63]). During Omicron, significantly higher risk of infection, hospitalization and severe-COVID-19 was observed amongst patients with asthma (severe-COVID-19: aHR=1.31[1.10-1.55]) and COPD (severe-COVID-19: aHR=1.36[1.12-1.66]) compared with controls. Severe exacerbation (requiring hospitalization) in the preceding year was associated with higher risk of poorer outcomes (Delta-severe-COVID-19: aHR=9.84[6.33-15.28]; Omicron-severe-COVID-19: aHR=19.22[15.35-24.06]). Risk was attenuated in the boosted group, with numerically lower HRs against hospitalization/severe-COVID-19 in the 4-dose group compared with the 3-dose group. InterpretationIncreased risk of COVID-19-related hospitalization and severe-COVID-19 was observed amongst patients with CLD compared with matched population controls, during Delta/Omicron predominance. Boosting attenuated serious COVID-19 outcomes.