The researchers will recruit volunteers from various organisations who are willing and able to be randomised to either working from home for 4 weeks followed by working in the office for 4 weeks, or vice versa. The goal is to assess whether working from home has an impact on the risk of symptoms of respiratory infection.

Working in the office entails to various extent contact with colleagues, and for some it includes close contact to others when using public transport to and from work. This likely increases the risk of transmission and many workplaces along with health authorities have strongly advised employees to work from home as much as possible during the COVID-19 pandemic. On the other hand, most people are infected from other family members, and working from home increases exposure to other family members.

There are few, if any trials on the effects of teleworking/home office on the risk of transmission of SARS-CoV-2 and other respiratory agents. Studies that have looked at associations between teleworking and COVID-19 have found a negative correlation.

A systematic review from the National Institute of Occupational Health (STAMI) showed that workers working from home experienced higher work satisfaction and productivity, while also reporting negative effects on work-life balance, professional isolation and working outside core hours. Effects on health outcomes were mixed. The quality of the studies was generally judged as low.

However, working at the office could mean increased exposure to transmission of SARS-CoV-2 and other respiratory agents. Thus, both interventions do pose potential benefits and harms for the participants.

Working from home is a broadly applied intervention nationally and internationally during the COVID-19 pandemic. Establishing what effect this intervention has on actual spread of SARS-CoV-2 and other respiratory agents could hence provide valuable insight to national and local authorities and decision-makers.

The researchers propose to conduct a trial to assess whether working at home impacts on employees' risk of respiratory infection and reduce the risk of work-related outbreaks. The aim is to reject the null hypothesis that working at home does not reduce the risk of respiratory infections or outbreaks among employees.

The researchers plan to conduct the trial as a two-arm multi-period crossover superiority trial where the employees are allocated into two equally sized groups. If this eases the recruitment of firms, the cross-over structure will be dropped.

The first and second arm will cross-over (change treatment) after four weeks. Week 1 and week 5 will be considered run-in periods for these arms, and the data collected these run-in weeks will not be used as outcome data in the statistical analysis.

The plan is to recruit 3-5 large firms with over 2000 eligible participants. Firms located in Oslo and neighbouring municipalities will be included. These are the areas That are seeing the highest incidence rates of SARS-CoV-2 in the ongoing covid-19 pandemic in Norway.

All consenting employees in the selected organizations are eligible to participate in the trial. The organizations can define in advance certain key personnel that cannot take part in the trial.

The investigators will compare the following interventions:

1. Participants will strive to be working from home every day. Participants can go to the office in order to complete tasks that cannot be completed from home.
2. Participants will be working from the office most days, but at least three days a week.

Inclusion criteria:

• Over 18 years old
• Employee in a company/organisation that has agreed to let their employees take part
• Willing and able to work form home for 4 weeks (most of the time)

Exclusion crieria:

- Unable to work from home

The intention is to enable sharing of an anonymised dataset with all interested parties.

After reporting of the trial findings, estimated to June 2023.