The effect of working at home versus at the office on risk of transmission of SARS-CoV-2 and other respiratory agents. A randomized controlled trial (study protocol)

Background: Working from home has in many countries been a strongly advised infection prevention during the COVID-19 pandemic. However, we have not found evidence that this intervention influences the transmission of SARS-CoV-2 or other respiratory agents. Randomized trials are needed to assess if working from home reduce the risk of respiratory infections or outbreaks among employees.

Methods: Randomized two-arm multi-period crossover superiority trial. We will recruit 3-5 large firms with over 2000 eligible participants, located in Oslo and neighbouring municipalities. 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 participants will be randomized (1:1) to either i) mainly work from home in 4 weeks, and then at the office in 4 weeks, or ii) first work in the office in 4 weeks and then at home. Our primary outcome will be the proportion of participants who report having symptoms of respiratory disease during the trial period (self-reported). Given a dropout rate of 50%, we assume we need to enrol > 5500 participants to be able to detect a 50% reduction in the risk of COVID-19.

Discussion: We expect there to be some bias in the self-reporting of symptoms of respiratory disease, since participants allocated to the going to the office group, will need to consider every day if they feel healthy, while participants staying at home will not have to consider this. Thus, we plan to look only at symptoms above a certain threshold