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.