SARS-CoV-2 infection in asymptomatic healthcare workers at a clinic in Chile

Asymptomatic SARS-CoV-2 infection of healthcare workers (HCWs) has been reported as a key player in the nosocomial spreading of COVID-19. Early detection of infected HCWs can prevent spreading of the virus in hospitals among HCWs and patients. We conducted a cross-sectional study to determine the asymptomatic infection of HCWs in a private clinic in the city of Santiago, Chile. Our study was conducted during a period of 5 weeks at the peak of transmission of SARS-CoV-2 in Chile. Nasopharyngeal samples were obtained from 413 HCWs and tested for the presence of SARS-CoV-2 using RT-qPCR. We found that a 3.14% of HCWs were positive for the presence of SARS-CoV-2 (14/413). Out of these, 7/14 were completely asymptomatic and did not develop symptoms within 3 weeks of testing. Sequencing of viral genomes showed the predominance of the GR clade; however, sequence comparison demonstrated numerous genetic differences among them suggesting community infection as the main focus of transmission among HCWs. Our study demonstrates that the protocols applied to protect HCWs and patients have been effective as no infection clusters due to asymptomatic carriers were found in the clinic. Together, these data suggest that infection with SARS-CoV-2 among HCWs of this health center is not nosocomial.

Validation of the Madigan ESS simulator

The Madigan Endoscopic Sinus Surgery (ESS) Simulator, developed by a multi-institution team led by Lockheed Martin, includes force-feedback instrument and virtual endoscope interaction with three-dimensional paranasal anatomy models derived from the Visible Human dataset, supplemented by a variety of graphical and auditory instructional aids embedded in the model. Our formal evaluation of Version 1.2 of the system focused on its validity as an ESS simulator. Run-time and survey data were collected for three groups of subjects on a common protocol progressing through the three basic ESS subtasks: navigation, injection, and dissection. Non-MD subjects performed the tasks on a simplified abstract virtual model with instructional aids (hoops for the navigation path, injection targets, dissection spheres, auditory feedback about task completion, and simulated patient heart rhythm). Non-ENT MDs progressed from this "novice" model to a simulated anterior ethmoidectomy on an "intermediate" model with the aids embedded in the reconstructed and segmented paranasal anatomy. Otolaryngologists ranging from second-year ENT residents through senior staff progressed through both the abstract and intermediate models, and then performed the simulated surgical procedure on an "advanced" model, consisting of the anatomy with no instructional aids. The procedural validity of the simulator is supported by a strong correlation between performance on the simulator and degree of prior ESS experience, by convergent correlation among independent measures of subject task performance, and by subjective evaluations by experienced ESS surgeons.