Infection prevention and control measures during the COVID-19 pandemic and airborne tuberculosis transmission during primary care visits in South Africa

Abstract

Background

Tuberculosis (TB) transmission in crowded health care settings poses considerable risks in high-burden regions. We assessed how COVID-19 pandemic-related infection prevention and control (IPC) measures might impact TB transmission in a South African primary care clinic.

Methods

In 2019 (prepandemic) and 2021 (pandemic), we collected clinical data, patient tracking data (person-time and spatial density), indoor CO₂ levels, and concentrations of Mycobacterium tuberculosis (Mtb) DNA in bio-aerosol samples. We estimated the risk of Mtb transmission during a 1-hour visit based on ventilation rate and duration of exposure.

Results

During the pandemic, clinics were less crowded, with lower mean person-time per day (209 vs 258 hours; P < 0.001). TB prevalence among patients also declined (1.1% vs 4.7%; P < 0.052). Environmental indicators suggested improved air quality, with lower CO₂ levels (555 vs 856 parts-per-million; P < 0.001) and higher ventilation rates (15.8 vs 6.3 air changes per hour; P < 0.001). These changes corresponded with a reduction in modeled Mtb transmission risk (0.04% vs 1.36%; P = 0.046). Airborne Mtb DNA was detected in both periods.

Conclusion

Pandemic-related IPC measures to control COVID-19 transmission were rigorously implemented and likely reduced transmission of airborne respiratory infections, supporting their continued implementation in healthcare settings postpandemic.