inclusion criteria: * icu admission for pneumonia complicated by respiratory failure. * rt-pcr (or equivalent) confirmed covid-19 infection. * intubated and on mechanical ventilation within 120 hours of initiation of mechanical ventilation. * age ≥ 3 years of age.

inclusion criteria: * icu admission for pneumonia complicated by respiratory failure. * rt-pcr (or equivalent) confirmed covid-19 infection. * intubated and on mechanical ventilation within 120 hours of initiation of mechanical ventilation. * age ≥ 3 years of age.

inclusion criteria: - icu admission for pneumonia complicated by respiratory failure. - rt-pcr (or equivalent) confirmed covid-19 infection. - intubated and on mechanical ventilation within 120 hours of initiation of mechanical ventilation. - age ≥ 3 years of age.

inclusion criteria: - icu admission for pneumonia complicated by respiratory failure. - rt-pcr (or equivalent) confirmed covid-19 infection. - intubated and on mechanical ventilation within 120 hours of initiation of mechanical ventilation. - age ≥ 3 years of age.

inclusion criteria: - icu admission for pneumonia complicated by respiratory failure. - rt-pcr (or equivalent) confirmed covid-19 infection. - intubated and on mechanical ventilation within 48 hours of initiation of mechanical ventilation. - age ≥ 3 years of age.

inclusion criteria: - icu admission for pneumonia complicated by respiratory failure. - rt-pcr (or equivalent) confirmed covid-19 infection. - intubated and on mechanical ventilation within 48 hours of initiation of mechanical ventilation. - age ≥ 3 years of age.