Fig. 2From: The University of Padua salivary-based SARS-CoV-2 surveillance program minimized viral transmission during the second and third pandemic waveFlow chart diagram reporting the number of subjects under surveillance and not in surveillance involved in the study. The 531 non-permanent staff subjects who did not participate in the study were excluded since, as non-permanent, their medical records were not always available to the Preventive Medicine of the University of PaduaBack to article page