MALAYA JOURNAL OF MATEMATIK Malaya J. Mat. 11(03)(2013), 286–293. http://doi.org/10.26637/mjm1103/005 A mathematical reason to wear a face mask during a COVID-19 like pandemic TCHILABALO ABOZOU KPANZOU * 1 ,EDOH KATCHEKPELE 2 AND ESSOMANDA TCHANDAO MANGAMANA 3 1,2,3 Laboratoire de Mod´ elisation Math´ ematique et d’Analyse Statistique D´ ecisionnelle (LaMMASD), D´ epartement de Math´ ematiques, Universit´ e de Kara, Togo. Received 09 March 2023; Accepted 08 June 2023 Abstract. The new coronavirus called COVID-19 started spreading in China since the end of 2019, and shortly, it became a serious matter over the entire world, infecting millions of people and killing many of them. That virus lead researchers to looking for ways to eradicate it, the first thing being to prevent people from getting contaminated. One way someone can protect himself and others is to wear a face mask as recommended by the World Health Organization. In this paper, we give a simple mathematical model showing why everyone should wear a face mask during a COVID-19 like pandemic. In order to illustrate the situation, we carry out a short simulation work, showing how various populations can be affected. We also show the number of contamination rounds needed to contaminate the whole population if nothing is done to stop the contamination process. AMS Subject Classifications: 92C99; 03C65. Keywords: Coronavirus, face mask, mathematical model, epidemiology, simulation. Contents 1 Introduction 286 2 The model without any policy 287 3 The model with ”wear-a-mask” (WAM) policy 289 4 Simulations 291 5 Concluding remarks 292 1. Introduction The new coronavirus disease called COVID-19 is caused by the virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and started spreading in China since the end of 2019. This has become a serious worldwide concern, especially in the most developed countries where the spread has taken most governments by surprise. Very quickly, variants of this virus also started circulating in different countries. The dominant ones are: Alpha (α) for B.1.1.7 (United Kingdom variant), Beta (β) for B.1.351 (South Africa), Gamma (γ ) for P.1 (Brazil), Delta (δ) for B.1.617.2 (India), etc. Since then, many methods have been used in order to flatten the curve of * Corresponding author. Email addresses: t.kpanzou@univkara.net (T.A. Kpanzou), ekatchekpele@univkara.net (E. Katchekpele), tchanesso@yahoo.fr (E. Tchandao Mangamana) https://www.malayajournal.org/index.php/mjm/index ©2013 by the authors.