* minor subject (age \<18 years) * person unable to give consent * refusal to participate * pregnancy * participating in another research * signs of respiratory decompensation requiring mechanical ventilation * diagnosis of pneumonia with sars-cov-2 not confirmed * oxygen dependence criterion exceeded i.e. need to maintain an oxygen flow rate greater than or equal to 6 liters / min to obtain: saturation by pulse oximetry (spo2) greater than or equal to 92% or arterial gas with value of pao2 greater than 60mmhg. * inability to maintain the prolonged sitting position (at least 2 hours) * subject with contraindications to hbot

* minor subject (age \<18 years) * person unable to give consent * refusal to participate * pregnancy * participating in another research * signs of respiratory decompensation requiring mechanical ventilation * diagnosis of pneumonia with sars-cov-2 not confirmed * oxygen dependence criterion exceeded i.e. need to maintain an oxygen flow rate greater than or equal to 6 liters / min to obtain: saturation by pulse oximetry (spo2) greater than or equal to 92% or arterial gas with value of pao2 greater than 60mmhg. * inability to maintain the prolonged sitting position (at least 2 hours) * subject with contraindications to hbot

- minor subject (age <18 years) - person unable to give consent - refusal to participate - pregnancy - participating in another research - signs of respiratory decompensation requiring mechanical ventilation - diagnosis of pneumonia with sars-cov-2 not confirmed - oxygen dependence criterion exceeded i.e. need to maintain an oxygen flow rate greater than or equal to 6 liters / min to obtain: saturation by pulse oximetry (spo2) greater than or equal to 92% or arterial gas with value of pao2 greater than 60mmhg. - inability to maintain the prolonged sitting position (at least 2 hours) - subject with contraindications to hbot

- minor subject (age <18 years) - person unable to give consent - refusal to participate - pregnancy - participating in another research - signs of respiratory decompensation requiring mechanical ventilation - diagnosis of pneumonia with sars-cov-2 not confirmed - oxygen dependence criterion exceeded i.e. need to maintain an oxygen flow rate greater than or equal to 6 liters / min to obtain: saturation by pulse oximetry (spo2) greater than or equal to 92% or arterial gas with value of pao2 greater than 60mmhg. - inability to maintain the prolonged sitting position (at least 2 hours) - subject with contraindications to hbot