The US Centers for Disease Control and prevention issued a statement 13 days ago, saying that in view of the current subtype BA. of COVID-19's The "mask order" implemented in the public transport system will be extended until May 3. (passengers wearing masks walk in the terminal at Reagan National Airport in Arlington, Virginia, on April 14) (passengers wearing masks walk outside the terminal at Reagan National Airport in Arlington, Virginia, on April 14.) (on April 14, passengers wearing masks checked in at Reagan National Airport in Arlington, Virginia, USA.) (on April 14, at Reagan National Airport in Arlington, Virginia, passengers wearing masks take an elevator in the terminal.) (passengers wearing masks walk in the terminal at Reagan National Airport in Arlington, Virginia, on April 14.) (Xinhua News Agency)