COVID-19 symptom duration: evidence from a survey of infected workers in Tokyo.

Introduction: The prevalence and duration of symptoms following COVID-19 infection vary substantially across individuals. However, little is known about the relationship between workers' job characteristics and the persistence of post-COVID symptoms. This study investigated the prevalence and duration of symptoms following COVID-19 infection and examined their associations with occupational characteristics. Methods: We conducted a large-scale retrospective survey of infected workers in February 2023. The survey collected information on symptom duration, job characteristics, and individual demographic, health, and socio-economic characteristics. We estimated adjusted odds ratios for prolonged symptoms using a three-month threshold while controlling for potential confounding factors. A sensitivity analysis was conducted using a one-month symptom-duration threshold. Results: Most infected workers experienced symptoms for less than one month. However, approximately 5% reported symptoms lasting three months or longer. Part-time workers had higher adjusted odds of experiencing symptoms for three months or more. Service workers, managers, and transportation workers tended to have lower odds of prolonged symptoms. However, the associations observed for occupational groups were not robust in the sensitivity analysis using a one-month threshold. Discussion: The findings suggest that the persistence of symptoms following COVID-19 infection varies across employment types and occupations. In particular, part-time workers may be at greater risk of long-lasting symptoms.