Fig. 4From: Impact of respirator versus surgical masks on SARS-CoV-2 acquisition in healthcare workers: a prospective multicentre cohortKaplan–Meier curve regarding unadjusted risk of a SARS-CoV-2-positive nasopharyngeal swab for healthcare workers (HCW) with infrequent (a) and frequent (b) exposure to COVID-19 patients (FFP2 filtering facepiece class 2)Back to article page