Risk of Severe Coronavirus Disease 2019 Disease in Individuals With Down Syndrome: A Matched Cohort Study From a Large, Integrated Health Care System.

Background: Down syndrome (DS) is associated with an increased risk of infections attributed to immune defects. Whether individuals with DS are at an increased risk of severe coronavirus disease 2019 (COVID-19) remains unclear.

Methods: In a matched cohort study, we evaluated the risk of COVID-19 infection and severe COVID-19 disease in individuals with DS and their matched counterparts in a pre-COVID-19 vaccination period at Kaiser Permanente Southern California. Multivariable Cox proportion hazard regression was used to investigate associations between DS and risk of COVID-19 infection and severe COVID-19 disease.

Results: Our cohort included 2541 individuals with DS and 10 164 without DS matched on age, sex, and race/ethnicity (51.6% female, 53.3% Hispanic, median age 25 years [interquartile range, 14-38]). Although the rate of COVID-19 infection in individuals with DS was 32% lower than their matched counterparts (adjusted hazard ratio [aHR], 0.68; 95% confidence interval [CI], .56-.83), the rate of severe COVID-19 disease was 6-fold higher (aHR, 6.14; 95% CI, 1.87-20.16).

Conclusions: Although the risk of COVID-19 infection is lower, the risk of severe disease is higher in individuals with DS compared with their matched counterparts. Better infection monitoring, early treatment, and promotion of vaccine for COVID-19 are warranted for DS populations.