SARS-CoV-2 Transmission Risk in the School Environment: a pilot case-ascertained prospective study to inform future school-based surveillance.

BACKGROUND: There is no current active or passive disease surveillance programme focused on schools in South Africa. As such the country is missing an opportunity to rapidly and effectively flag and address pathogen outbreaks, for example SARS-CoV-2, in a key closed setting. Furthermore, the role of school transmission in the spread of the SARS-CoV-2 virus within communities is uncertain.  Objective. This pilot study, conducted during March 2022 in Cape Town, aimed to indicate the feasibility of conducting intense active contact-tracing in a school environment prior to a large national study to compare school versus community SARS-CoV-2 transmission risk.  Methods. We conducted a pilot school-level case-ascertained prospective study with a component of enhanced surveillance. Following study initiation, the first learner at a participating school who tested SARS-CoV-2 positive (via Polymerase Chain Reaction (PCR) or a Rapid Antigen Test (RAT)) was invited to join the study as the index case and all their school-based close contacts were followed up telephonically, monitored for symptoms for 14 days, and tested using a PCR if any symptoms were reported.  Results. On 8th March 2022, a student with RAT laboratory-confirmed COVID-19 was identified and they and their guardian consented to participate as the index case. Of the 11 eligible close contacts, six provided consent/assent and completed symptom monitoring calls until the end of the 14-day study period. The Secondary Attack Rate (SAR) was 2/11 (18.18%) of all close contacts who were at risk of infection, 2/4 (50.0%) of all those close contacts who developed symptoms, and 2/4 (50.0%) of all those close contacts who developed symptoms and were tested for SARS-CoV-2. During the same period, the school reported that nine of the 926 learner body tested COVID-19 positive (0.97%). Total hours spent conducting monitoring for 6 learners was 27 hours, with each learner requiring approximately 4.5 hours of contact time during the study period.  Conclusion. This is the first South African school-based COVID-19 transmission study, the results of which can inform national discussions regarding the role of schools and school-based active and passive surveillance in pathogen prevention and control.

Effect of lung volume on lung resistance and elastance in awake subjects measured during sinusoidal forcing.

BACKGROUND: Although lung volume may be changed by certain procedures during anesthesia and mechanical ventilation, dependence of the dynamic mechanical properties of the lungs on lung volume are not clear. Based on studies in dogs, the authors hypothesized that changes in lung mechanics caused by anesthesia in healthy humans could be accounted for by immediate changes in lung volume and that lung resistance will not be decreased by positive end-expiratory airway pressure if tidal volume and respiratory frequency are in the normal ranges. METHODS: Lung resistance and dynamic lung elastance were measured in six healthy, relaxed, seated subjects during sinusoidal volume oscillations at the mouth (5 mL/kg; 0.4 Hz) delivered at mean airway pressure from -9 to +25 cmH2O. Changes in lung volume from functional residual capacity were measured with inductance plethysmographic belts. RESULTS: Decreases in mean mean airway pressure that caused decreases in lung volume from functional residual capacity comparable to those typically observed during anesthesia were associated with significant increases in both dynamic lung elastance and lung resistance. Increases in mean mean airway pressure that caused increases in lung volume from functional residual capacity did not increase lung resistance and increased dynamic lung elastance only above about 15 cmH2O. CONCLUSIONS: Increases in dynamic lung elastance and lung resistance with anesthesia can be explained by the accompanying, acute decreases in lung volume, although other factors may be involved. Increasing lung volume by increasing mean airway pressure with positive end-expiratory pressure will decrease lung resistance only if the original lung volume is low compared to awake, seated functional residual capacity.