Tracing contacts to evaluate the transmission of COVID-19 from highly exposed individuals in public transportation

TL;DR

This study models COVID-19 transmission in buses using contact tracing data, revealing higher transmission among healthcare workers and emphasizing targeted public transportation policies.

Contribution

It introduces a data-driven contact tracing model for buses and compares transmission dynamics with city-wide data, highlighting risks for healthcare workers.

Findings

Effective reproduction number inside buses aligns with city-wide trends.

Healthcare workers exhibit higher transmission rates in buses.

Targeted policies are needed for highly exposed groups.

Abstract

We investigate, through a data-driven contact tracing model, the transmission of COVID-19 inside buses during distinct phases of the pandemic in a large Brazilian city. From this microscopic approach, we recover the networks of close contacts within consecutive time windows. A longitudinal comparison is then performed by upscaling the traced contacts with the transmission computed from a mean-field compartmental model for the entire city. Our results show that the effective reproduction numbers inside the buses, $Re^{bus}$, and in the city, $Re^{city}$, followed a compatible behavior during the first wave of the local outbreak. Moreover, by distinguishing the close contacts of healthcare workers in the buses, we discovered that their transmission, $Re^{health}$, during the same period, was systematically higher than $Re^{bus}$. This result reinforces the need for special public transportation policies for highly exposed groups of people.