Statistical methods
For all study objectives, unless otherwise specified, we summarized data descriptively using frequencies for categorical variables and measures of central tendency for continuous variables. Proportions were compared using the Chi-square test or the Fisher exact test when needed. Mean values were compared using the Wilcoxon-Rank-Sum or Kruskal-Wallis test were used.
Bivariable analyses were performed to compare patient and clinical characteristics by immunocompromising condition and to compare factors with dichotomized version of time to negative test result (< 30 days, >30 days). For those that had at least one subsequent test, multiple SARS-CoV-2 test results were described graphically using a line segment plot. Kaplan-Meier (KM) analysis was stratified by oncology classification, symptomatic/asymptomatic, and ALC classification. KM curves were described by median times to negative (defined as first of two consecutive negatives) and compared with log rank tests. For those with at least one subsequent test, subjects were considered censored at the last test if they did not have two consecutive negative test results.