COVID-19(22) SARS-CoV-2(16) Oxygenation(6) Treatment(6) Infection(6) viral replication(6) airway(6) Viral(6) impair(4) expression(4) viral infection(4) Human(4) subject(4) airway pH.(4) SARS-CoV-2 viral replication(4) Host(4) viability(4) inhibited(4) Patient(4) had no(4) mechanisms(4) host defense(4) Activation(4) Trial(4) patient safety(4) multiplicity(4) Defense(4) cells(4) raise(4) Lung function(4)