Cases per ward day amongst HCWs on green wards (A ) were
strongly correlated with the number of community cases identified the
previous week (p-value < 5x10-5, Pearson
correlation test), suggesting that infection in the community explains
cases amongst HCWs on these wards. Conversely, cases per ward day
amongst HCWs on red wards (B) did not correlate with the
community incidence (p-value > 0.7, Pearson correlation
test). R2 values shown in the figures are coefficients
of determination arising from linear regression calculations performed
using the Mathematica software package (version 12.1.0.0).