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People who work shifts seem to end up in hospital significantly more often with COVID-19 than people with regular work patterns, suggests a study published online in the journal Thorax.
Researchers found that shiftwork could be just as important a risk factor as well-known high-risk traits such as ethnicity and living in poorer areas. Therefore, they should be taken into account in future public health actions aimed at reducing COVID-19 infections.
Shift work in this study referred to a work schedule that falls outside of regular working hours of 9 a.m. to 5 p.m., including long-term night shifts and work schedules in which employees change or change their shifts.
Shift work is becoming more common around the world, with 10% to 40% of workers in most countries doing it. Previous studies have identified adverse health effects from shift work such as respiratory diseases, diabetes, cancer, and non-COVID-19 infectious diseases. It is believed that this could be due to sleep deprivation, poor diet, and disruption of the body's natural 24-hour (circadian) cycle.
Given that the immune system is regulated by the circadian clock, it is possible that shift work could lead to "circadian misalignment" and increase a person's susceptibility to COVID-19 infection – a theory put forward by researchers at the Universities of Manchester and Oxford represented in the UK and the University of the West Indies set out to investigate.
They used data from more than 280,000 participants, ages 40 to 69, when they took part in the UK Biobank Study (2006-10), along with data from other sources such as hospital episode statistics and GP records.
They excluded participants who had COVID-19 tests performed outside of secondary care.
To find out if shift work was linked to a positive COVID-19 test in the hospital, the researchers compared workers who had never worked shifts with participants who worked irregular or permanent shifts.
The data showed that shift workers tended to be younger and male, had higher body mass index (BMI), smoked more, had lower alcohol consumption, non-white ethnicity, and higher levels of deprivation.
The results showed that a person who worked irregular shifts was more than twice as likely to test positive for COVID-19 as a person who did not work shifts.
Similarly, a person working permanently appeared to be 2.5 times more likely to develop COVID-19 even when other factors such as age, gender, and ethnicity were taken into account.
The researchers also looked at whether the type of shift work affects the association with COVID-19.
They found that day and night shift workers (who work irregular and continuous night shifts) were more likely to get a positive COVID-19 test compared to workers who did not work shifts. In fact, those who worked irregular night shifts were three times more likely to test positive for the virus in hospitals.
And those higher risks were largely unchanged when factors such as sleep duration, BMI, alcohol, and smoking were taken into account.
According to the researchers, key workers and healthcare workers are at higher risk of COVID-19, which could possibly explain their findings if shiftworkers were concentrated in these groups.
They then examined the effects of a person's physical proximity to a colleague in the workplace, combined with estimated disease exposure. compared participants in each occupational area (not essential, essential and in health care); and compared shiftwork and non-shiftwork colleagues.
In all of these cases, shift work was still significantly linked to COVID-19, meaning that shift work was associated with higher chances for COVID-19 regardless of the type of occupational sector.
They suggest their findings could be due to increased workspace occupancy for shift workers over 24 hours, shorter cleaning time between shifts, and fatigue, resulting in lower awareness of health and safety measures.
Other explanations could be that shift work could alter the immune system's response to infection.
This is an observational study so no cause can be determined. The authors also acknowledge some other limitations such as the fact that data collected via questionnaire for the UK biobank and used in the study was recorded at least 10 years before COVID-19 and although some of the data was updated through hospital episodes were statistics it could not be viewed as a simultaneous record.
However, one of the study's strengths was the fact that it analyzed a large number of participants.
The author Dr. John Blaikley of the University of Manchester said, "This study shows a fairly strong association between shift work and hospitalization for COVID-19, even after controlling for existing COVID-19 risk factors."
The co-author Dr. Hannah Durrington of the University of Manchester added, "We believe it should be possible to significantly reduce these risks through thorough hand washing, the use of face shields, adequate intervals and vaccinations."
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Shift work is linked to a positive COVID-19 status in hospital patients, thorax (2021). DOI: 10.1136 / thoraxjnl-2020-216651
British Medical Journal
Hospital shift workers are up to three times more likely to be COVID-19 positive (April 26, 2021).
accessed on April 26, 2021
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