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The protective effect of masks

Men play chess in the city of Sonargaon, Bangladesh, in November 2020

Nishat Thechotobhai / Pexels

Widespread and proper use of masks reduces transmission of the novel coronavirus and COVID-19 cases, according to the largest study ever conducted on the subject. Laboratory experiments had already shown that masks reduce the amount of virus released into the air and lower the likelihood of transmission, but there was previously little data on effectiveness in real-life conditions. To obtain this information, researchers from the USA, Australia, and Bangladesh carried out a study involving 342,126 residents of 600 villages in the Asian country between November 2020 and April 2021: just over half (178,288 people) were given masks, as well as information on how to wear them correctly and the importance of doing so. For eight weeks, these individuals were also encouraged to wear the masks by local leaders and were given personal reminders. The other 163,838 participants (the control group) were monitored with no intervention. In the first group, 42.3% of people wore masks. Only 13.3% did so in the control group, according to the study, which has been submitted for publication in a scientific journal. The intervention reduced symptomatic cases in the general population by 9.3%. The reduction was even greater (35%) among people aged over 65, who are most at risk of dying from the disease.