# Morocco’s population contact matrices: A crowd dynamics-based approach using aggregated literature data

## TL;DR

This paper introduces a new method to estimate contact patterns in Morocco using a social force model, showing how social distancing and panic could significantly affect contact rates.

## Contribution

A novel crowd dynamics-based approach to estimate contact matrices integrating social distancing and panic scenarios.

## Key findings

- Social distancing could reduce contacts by 95%.
- Panic increases contact numbers by 11%.
- Estimated matrices are highly assortative and align with prior studies like POLYMOD.

## Abstract

Estimation of contact patterns is often based on questionnaires and time-use data. The results obtained using these methods have been used extensively over the years and recently to predict the spread of the COVID-19 pandemic. They have also been used to test the effectiveness of non-pharmaceutical measures such as social distance. The latter is integrated into epidemiological models by multiplying contact matrices by control functions. We present a novel method that allows the integration of social distancing and other scenarios such as panic. Our method is based on a modified social force model. The model is calibrated using data relating to the movements of individuals and their interactions such as desired walking velocities and interpersonal distances as well as demographic data. We used the framework to assess contact patterns in different social contexts in Morocco. The estimated matrices are extremely assortative and exhibit patterns similar to those observed in other studies including the POLYMOD project. Our findings suggest social distancing would reduce the numbers of contacts by 95%. Further, we estimated the effect of panic on contact patterns, which indicated an increase in the number of contacts of 11%. This approach could be an alternative to questionnaire-based methods in the study of non-pharmaceutical measures and other specific scenarios such as rush hours. It also provides a substitute for estimating children’s contact patterns which are typically assessed through parental proxy reporting in surveys.