Transmissibility and control of tuberculosis in school outbreaks: a modeling study based on four outbreaks in China

The elevated incidence of tuberculosis (TB) outbreaks in schools poses a significant challenge to prevention and control efforts in China. The commonality among most outbreaks is the failure to isolate patients at an early stage. Early isolation of TB cases is crucial for reducing the spread of TB within schools. This study aims to quantify the impact of different isolation proportions and durations on the attack rate of TB in schools. It explored the intervention effects of isolation measures in preventing and controlling TB in school settings. The goal is to provide insights that can serve as a reference for reducing the occurrence of TB outbreaks in schools.

We collected data from 4 school TB outbreaks. Susceptible-Exposed-Infected-Recovered (SEIR) model was used to fit the collected data and calculate transmissibility. Susceptible-Exposed-Infected-Quarantined-Recovered (SEIQR) model was employed to evaluate the effect of isolation. Effective reproduction numbers and cumulative incidence were used to quantify the transmissibility of TB.

In the 4 outbreaks, the majority of student cases were distributed in high grades of high school and universities, with a widespread occurrence of significant intervention delays. The median ascending reproduction value for the 4 outbreaks was 18.44 [interquartile range: 15.40-20.11]. Isolating 100% of the patients at the first month could reduce the number of cases by 99.47%, 87.99%, 96.48%, and 99.16%, respectively.

This study suggests that high schools and universities may represent significant high-risk environments for TB outbreaks. Early detection and isolation of cases are important strategies that can help reduce the risk of TB outbreaks, with observed case reductions of up to 99.47% when implemented promptly.