The administration of U.S. President Joe Biden is considering ordering federal employees to prove that they have been vaccinated against COVID-19.Also under consideration are requirements for regular testing and wearing of face coverings or masks.The possible actions would represent a major policy change as concerns grow about the spread of the highly infectious Delta variant of the coronavirus.A person who knows about the plans spoke to the Associated Press but asked not to be identified.The person said the possible official order, or mandate, for vaccination could be put in place even if an area does not have a high rate of transmission of the virus.Administration officials are expected to release their final decision this week.The Office of Management and Budget says that in 2020 there were more than 4.2 million federal workers including those in the military.Biden suggested on Tuesday that expanding a vaccination requirement to all federal workers was "under consideration." He offered no additional details.