By the beginning of April 2021, the number of people infected during the COVID-19 pandemic had risen to more than 130 million people of whom more than 2.8 million died. The SARS-CoV-2 virus responsible for COVID-19 is transmitted particularly by droplets or aerosols emitted when an infected person speaks, sneezes or coughs. This is how the viruses and other pathogens spread through the environment and transmit infectious diseases when they are inhaled by someone else.