The coronavirus pandemic Mask requirement Biden is requiring the use of masks and social distancing in all federal buildings, on federal lands and by federal employees and contractors. Consistently masking up is a practice that science has shown to be effective in preventing the spread of the coronavirus, particularly when social distancing is difficult to maintain. He is challenging all Americans to wear a mask for the first 100 days of his administration. That’s a critical period, since communities will still be vulnerable to the virus even as the pace of vaccination increases in pursuit of Biden’s goal of 100 million shots in 100 days.