The arrival of the first COVID-19 vaccine will not mean people can throw away their face masks, experts say. Face coverings, social distancing and a lot of handwashing still will be required for some time after COVID-19 vaccines become available. But for how long? That depends on how effective the vaccines are and how long protection lasts. Such questions will not be answered when the first injections arrive. "This vaccine is not likely to be a suit of armor," said William Schaffner, an expert on infectious disease at Vanderbilt University Medical Center in Tennessee. In other words, a vaccine is not likely to be 100 percent effective. Seasonal influenza vaccines, for example, have been 60 percent effective, at best, in recent years. The least efficient vaccines were only 10 percent effective. The United States Food and Drug Administration, FDA, has said it aims to have a 50 percent rate of effectiveness in COVID-19 vaccines.