COVID-19: The Effectiveness of Free Face Mask Distribution

The Effectiveness of Distributing Free Face Masks to Increase Use of Face Masks During the COVID-19 Pandemic. A Randomised Experiment in Stovner District, Oslo, Norway

The investigators will carry out a randomised trial of free face mask distribution in Stovner District, Oslo, Norway. Ten grocery stores will serve as study sites. Over three weeks the stores will be randomised daily to having "corona hosts" outside their entrance, handing out face masks to customers. The investigators will compare the proportion of customers who wear face masks as they enter the store in stores with or without face mask distribution.

The team members from the Stovner district-administration will send a numbered list to Norwegian Institute of Public Health-team, with the names of the stores. The ordering of the stores will define the numbers used to represent each store in the randomisation process. Using Stata software, we will carry out 13 separate and independent randomisations, each assigning the intervention to half the included stores. An additional randomisation to the treatment or control group will be carried out for a marginal store each day in the event of an odd number of stores. Unless it proves too logistically cumbersome, we will also randomise the corona hosts, i.e. the store they are allocated to will be decided through randomisation.

The analyst will receive a dataset in a format which makes it impossible for him/her to know which of the two arms in the dataset represents intervention or control.

"Corona hosts" will be placed at the entrance of the intervention stores, and hand out face masks to customers entering the store.

All grocery stores in the Stovner district are eligible as long as they have not, or only sporadically, had free distribution of face masks previously. At the customer level, we will only include those 12 years or older (age based on the outcome assessor's judgement).

The investigators will share the full dataset as soon as it as ready. All data are anonymous, so there are no person data issues to take into consideration.

Elgersma IH, Fretheim A, Indseth T, Munch AT, Johannessen LB, Hansen CE. The Evaluation of a Social Media Campaign to Increase COVID-19 Testing in Migrant Groups: Cluster Randomized Trial. J Med Internet Res. 2022 Mar 24;24(3):e34544. doi: 10.2196/34544.