OCCUPATIONAL CIRCADIAN RHYTHM DISORDERS AND THE RISK OF COVID-19 IN MEDICAL WORKERS
Authors:   North-Western Public Health Research Center, Saint Petersburg, Russia, Sorokin G.A. , Chistyakov N.D. ,   North-Western Public Health Research Center, Saint Petersburg, Russia, Chernysheva M.P. ,   Saint Petersburg State University, Saint Petersburg, Russia,   Saint Petersburg Medical and Social Institute, St. Petersburg, Russia, Сhalkina O.N ,   North-Western Public Health Research Center, Saint Petersburg, Russia
Published: May 2022

The issue of occupational circadian rhythm disorders and the risk of COVID-19 in medical workers is considered in the following three aspects: chronobiological (circadian rhythm disorders in shift work are a health risk factor), immunological (chronobiological vulnerability to viral infections in night shift work), medico-social (medical care providers working the night shift are a high-risk group). The purpose of the study was to analyze the effect of circadian rhythm disorders associated with night shift work among doctors and nurses on the risk of COVID-19. Material and methods. Four groups of employees of St. Petersburg medical organizations were examined: doctors and nurses working shifts and working the day shift only; infection with COVID-19; diseases detected during a medical examination of workers with and without COVID-19; indicators of the work regime (shift work, night shift work and work without night shifts, possibility to take a nap during the night shift, years in night shift); workload indicators (length of the working week, intensity and pace of labor actions, including the level of attention); degree and frequency of regular fatigue at work, the time the fatigue starts and ends. The workload was determined by the following indicator - the number of physiological standard hours per calendar week. Results. The relative risk of COVID-19 among doctors working the night shift is 1.51 times higher compared to doctors working the day shift only (RR=1.51; 1.22-0.87). Among nurses, the effect of the night shift on the risk of COVID-19 is lower compared to doctors (RR=1,06.2; 0.66-1.69). In nurses with moderate and severe fatigue working the night shift, the risk of COVID-19 is higher RR=1.43 (0.67-3.04) compared to nurses who are not tired or a little tired. The workload of doctors and nurses working the night shift equaled to 49.2 ± 0.7 standard hours; the workload of nurses added up to 49.8 ± 0.9 standard hours, while the workload of care providers working the day shift only equaled to 37.5 ± 0.6 and 39.1 ± 0.6 standard hours, respectively. Additional one hour of workload per week increases the risk of COVID-19 by 0.6% with night shifts and by 1.1% with day shifts only. The number of years in night shift from one to 9 years increases the risk of COVID-19. However, over nine years in night shift does not increase the risk. Lack or rare nap in night shift increases the relative risk of COVID-19 1.4 times in nurses and 1.2 times in doctors. With a total time of less than one hour between shifts, the relative risk increases 1.5 times in doctors and 1.7 times in nurses. The rate of gastrointestinal diseases among doctors with COVID-19 (11.4± 3.4%.) is higher compared to doctors without COVID-19 (6.1±3.5%). Conclusion. 1. The relative risk of COVID-19 among doctors working the night shift is 1.5 time higher compared to doctors working the day shift only (RR=1.51; 1.22-0.87). Among nurses, the night shift impact on the COVID-19 risk in lower (RR=1,06; 0.66-1.69). 2. In night shift, the COVID-19 risk is affected by circadian rhythm disorders and stress associated with high workload due to chronic fatigue. Additional one physiological standard hour of workload per week increases the COVID-19 risk by 0.6% ± 0.3%. 3. In doctors and nurses working the night shift, the COVID-19 risk increases over threefold with years in night shift from one to nine. After 9 years in night shift, the COVID-19 risk decreases. 4. The rate of gastrointestinal diseases among doctors with COVID-19 (11.4± 3.4%.) is higher compared to doctors without COVID-19 (6.1± 3.5%).