Administration, Inhalation 1 Article 1 COVID-19 1 COVID-19 Vaccines 1 Electric NO generator Humans 1 Klebsiella pneumoniae 1 Methemoglobin 1 Nitric Oxide 1 Nitric oxide 1 Nitrogen dioxide 1 Oxygen Saturation 1 Pilot Projects 1 Pulmonary vasodilator 1 SARS-CoV-2 1 Spontaneous breathing 1 adult 1 airflow 1 arterial pressure 1 artificial ventilation 1 breathing pattern 1 calcium hydroxide 1 chemiluminescence immunoassay 1 chemoluminescence 1 clinical article 1 controlled study 1 coronavirus disease 2019 1 coughing 1 drug dose increase 1 expiratory nitric oxide 1