COVID-19 pandemic changes in social behavior relevant for transmission of Mycobacterium tuberculosis

Objective Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is spread through the air. Although extensive data has shown that TB case notifications decreased during the COVID-19 pandemic, there is little known about the extent to which these reductions were due to a decrease in transmission, rather than delays in healthcare seeking and diagnosis. We used data from CONTEXT, a population-based cross-sectional study which enrolled newly diagnosed cases of extensively drug-resistant (XDR) or pre-extensively drug resistant (pre-XDR) TB in KwaZulu-Natal, South Africa from 2019 to 2023 and recorded information on their contacts. Results We found that close contacts declined by 36% from 2019 to 2020 (p = 0.005). Casual contacts at locations where participants routinely spent time declined by 30% (p = 0.16). Based on our findings, substantially lower population-level risk of transmission could be expected between 2020 and 2022 in this region of South Africa. These data are useful for understanding the extent of the reduction in Mtb transmission during the pandemic.