COVID-19 incidence in a cohort of public transport workers

Abstract

Background: Previous research has shown an excess risk of COVID-19 among several occupations, but data on public transport workers are scarce. To investigate the occupational risk posed by contact with the public, we followed up the incidence of COVID-19 in a cohort of public transport workers.

Methods: We identified the incident cases of COVID-19 between 1 September 2020 - 6 May 2021 in a cohort of 2,052 employees of a public transport agency in Sardinia, Italy. The diagnosis of COVID-19 was based on a positive molecular test. To calculate the expected events, we applied the age- and gender-specific incidence rates of the regional population in the same time period to the correspondent strata of the study cohort. We estimated the relative risk (RR) of COVID-19 as the ratio between the observed and the expected events and its 95% confidence interval (95% C.I.) among the total cohort and in two sub-cohorts: bus drivers, and the rest of the personnel (administrative staff, train and metro drivers, workers in the mechanical shop, and in the railroad maintenance, and security).

Results: Bus drivers run an elevated risk of COVID-19 (RR = 1.4, 95% C.I. 1.07 - 1.79). There was no excess risk among the sub-cohort including the rest of the personnel.

Conclusions: Our study suggests an excess risk of COVID-19 among bus drivers even in a relatively low incidence area, which could imply inadequacy of the preventive measures in place. Further, larger size studies with detailed information on personal and lifestyle characteristics are warranted.

Figure 1.

Covid-19 weekly rate by study sub-cohort along the 34 weeks of follow-up between 1 September 2020 and 6 May 2021.

Supplemental Figure 1:

Time trend of the COVID-19 crude rate between 1 September 2020 and 6 May 2021 in Italy (black solid line), Sardinia (black dotted line), bus drivers (grey solid line) and other employees of the transport agency (grey dotted line).