Public health advice for avoiding respiratory illness is largely unchanged since the Spanish flu of 1918, one of history’s deadliest pandemics. Keep a safe distance from other people. Wash your hands frequently with soap and water to kill any germs you may have picked up. Cover your nose and mouth with a face mask—even one fashioned from a bandana will do. Such guidance is based on the understanding that respiratory infections spread through virus-carrying droplets that are expelled when infected people cough, sneeze, or breathe.
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Source: Phys.org