Tracking social distance: Exploring ways to safely open events

Six months into the COVID-19 crisis, we bite our regularly washed fingernails waiting for a vaccine, but for now, behavioural interventions are the only medicine. How do we find out which interventions work? To answer this question, we decided to measure their efficacy through experiments. One Art Fair and around 200,000 data points later, we are starting to assess the effects of different settings at public events on social distancing, i.e., the interactions between people. 

Currently, the main public recommendation to avoid infection is to maintain distance from one another – in the Netherlands, this distance is set at 1.5 meters. Yet there is little research available to judge to which degree people adhere to this recommendation, and how they can be nudged to follow it. To recommend the best guidelines, it is vital that we study how effective different behavioural interventions are in promoting this social distance.

This journey started last May when the Science versus Corona team discussed ways to study behavioural interventions (see Virus transmission is dependent on both the characteristics of COVID-19 and the behaviour of individuals, i.e., whether people are in contact with each other. These contacts can be thought of as a network where individuals are represented by nodes and are connected when they have been in physical proximity long enough to transmit the virus. Such a network is called the “contact network”. We can compare the effectiveness of behavioural interventions by comparing the contact network when different interventions are in place. The indicators used in this comparison are termed Behavioral Contact Network (BECON) indicators. If, for instance, an intervention, such as wearing face masks, reduces the number of contacts a person has with others, it will lead to a contact network in which the virus could not spread as easily — the intervention shows promise.

By a stroke of luck, shortly after submitting the BECON paper, Science versus Corona found the Smart Distance Lab (SDL), a group of partners assessing how to organise large public events safely. SDL planned an Art Fair with this goal. It was the first experiment of its kind in Amsterdam and the perfect venue to compare BECON indicators across different settings. By dividing the three-day Art Fair into different time slots (i.e., experimental conditions), we could implement various behavioural interventions.

At ticket purchase, a questionnaire was administered to all visitors of the Art Fair about their adherence to public safety guidelines, their attitudes toward these guidelines, and their general COVID-19 worries. Inside the hall, infrared and regular cameras by Centillien measured the temperature of guests and recorded their movements throughout the exhibition. At the event, we handed out “Social Distancing Sensors” (SDS), designed by Focus Technologies and Sentech, to each visitor. These wearable electronic devices detect the presence of another device within a 1.5 m radius and can light up, vibrate, or make a sound to alert the wearer to increase social distance. The devices also record all the contacts people made while wearing them, and these data can be used to partially reconstruct the contact network and compute BECON indicators.

The contact data from the SDS’s were used to test whether the following interventions affected social distancing behaviour:

  1. Wearing facemasks,
  2. Three variations —none, one-directional, and bi-directional — of walking directions pasted on the floor, and,
  3. Buzzing sensors to alert people when they are within 1.5 m of someone else

The event was a huge success, with almost 700 visitors volunteering to wear the SDS’s at the Art Fair over three days. The response to the sensors was overwhelmingly positive, with many visitors enthusiastically wearing their sensors for the advancement of science. All this information and data will be used in the coming weeks to better understand which behavioural interventions show promise. 

In a mere four months, from a theoretical paper to a completed experiment; a herculean effort involving artists, companies, research institutes, and universities together collecting a magnitude of data. As we begin to analyse the data in the coming weeks, we may be able to provide recommendations to the government and public venues about best practices. Research like this is crucial for reopening safely – we need a better understanding of how behaviour can be shaped in public spaces.