Shift Work Is Associated with Increased Risk of COVID-19: Findings from the UK Biobank Cohort

Background: Despite the strong evidence on immunological effects of shift work and consequent vulnerability for infection, there is a dearth of evidence on the association between shift work and COVID-19 infection. The main objective of this study is to assess whether shift work, particularly night shift, increases the odds of COVID-19 infection.Methods: This study is based on the data from UK Biobank participants who were tested for COVID-19 infection, covering the period from 16th March to 27th July 2020. Participants were categorised as non-shift workers, day shift workers, mixed shift workers and night shift workers. The prospective association between shift work and COVID-19 infection were explored after controlling for age, gender, ethnic minority status, income, education, Townsend deprivation quintile, sleep duration, sleep problems, daytime sleepiness, overall health and obesity.Findings: Among the 12,428 participants ((13.2% positive cases) around 1 in 6 were frontline health workers (16.2%) with 1 in 5 involved in a shift work-based job (21.2%). Within the shift work-based jobs, people who worked mostly night shift were at the highest risk of COVID-19 infection (23.6%, P-value <0.001). Adjusted logistics regression model suggest that compared with their counterparts, people employed in a night-shift based job were 1.82 times (95% confidence interval 1.40 to 2.37) more likely to have COVID-19 infection Although health workers were found to have a significantly higher risk of COVID-19 infection than other occupational groups (14.6 vs 8.8%), and a significant proportion of the healthcare workforce was comprised of shift workers (37.1 % vs 17.2), this did not confound the association between shift work and COVID-19 infection. Sensitivity analysis, focusing on people working in a non-healthcare setting, suggests that people in shift work based jobs were 1.79 times (95% confidence interval 1.09 to 2.95) more likely to have COVID-19 infection than their counterparts.Interpretation: People in shift based job are more likely to have a positive test result for COVID-19 than their counterparts, and this association is robust to adjustment for predisposing sociodemographic factors.Funding: NoneDeclaration of Interests: None.Ethics Approval Statement: The UK Biobank study has approval from the North West Multi-centre Research Ethics Committee, the Patient Information Advisory Group, and the Community Health Index Advisory Group.