inclusion criteria: - be age 50 or over; not pregnant (will undergo pregnancy testing if below age 55); - have had a positive pcr-based test confirming the diagnosis of covid-19 within 5 days (+/-2 day)of study enrollment* - have had clinical signs of severe acute respiratory syndrome or pneumonia (ie. dyspnea, cough,fever) that primary team feels like patient needs rescuing with ld-rt.** - have visible bilateral consolidations/ground glass opacities on chest imaging - require supplemental oxygen at the time of enrollment, defined by inability to wean from supplemental oxygen within 24 hours prior to enrollment. - not require intubation within 12 hours of randomization (ie, not screen fail). intubation after enrollment but within 12 hours of randomization will be defined as a screen failure for both the ld-rt and control cohorts. - be enrolled within 5 days (+/- 2) of first hospitalization for covid-19. prior hospitalization for covid-19 will be an exclusion criteria (prior ed visits are permissible). - willingness and ability of the subject to comply with scheduled visits, protocol-specified laboratory tests, other study procedures, and study restrictions - evidence of a signed informed consent/assent indicating that the subject is aware of the infectious nature of the disease and has been informed of the procedures to be followed, potential risks and discomforts, potential benefits, and other pertinent aspects of study participation

inclusion criteria: - be age 50 or over; not pregnant (will undergo pregnancy testing if below age 55); - have had a positive pcr-based test confirming the diagnosis of covid-19 within 5 days (+/-2 day)of study enrollment* - have had clinical signs of severe acute respiratory syndrome or pneumonia (ie. dyspnea, cough,fever) that primary team feels like patient needs rescuing with ld-rt.** - have visible bilateral consolidations/ground glass opacities on chest imaging - require supplemental oxygen at the time of enrollment, defined by inability to wean from supplemental oxygen within 24 hours prior to enrollment. - not require intubation within 12 hours of randomization (ie, not screen fail). intubation after enrollment but within 12 hours of randomization will be defined as a screen failure for both the ld-rt and control cohorts. - be enrolled within 5 days (+/- 2) of first hospitalization for covid-19. prior hospitalization for covid-19 will be an exclusion criteria (prior ed visits are permissible). - willingness and ability of the subject to comply with scheduled visits, protocol-specified laboratory tests, other study procedures, and study restrictions - evidence of a signed informed consent/assent indicating that the subject is aware of the infectious nature of the disease and has been informed of the procedures to be followed, potential risks and discomforts, potential benefits, and other pertinent aspects of study participation

inclusion criteria: - have had a positive test confirming the diagnosis of covid-19 - have had clinical signs of severe acute respiratory syndrome or pneumonia (dyspnea, cough, fever) that primary team feels like needs rescuing with treatments - have visible consolidations/ground glass opacities on chest imaging - requiring supplemental oxygen - willingness and ability of the subject to comply with scheduled visits, protocol-specified laboratory tests, other study procedures, and study restrictions - evidence of a signed informed consent/assent indicating that the subject is aware of the infectious nature of the disease and has been informed of the procedures to be followed, potential risks and discomforts, potential benefits, and other pertinent aspects of study participation

inclusion criteria: - have had a positive test confirming the diagnosis of covid-19 - have had clinical signs of severe acute respiratory syndrome or pneumonia (dyspnea, cough, fever) that primary team feels like needs rescuing with treatments - have visible consolidations/ground glass opacities on chest imaging - requiring supplemental oxygen - willingness and ability of the subject to comply with scheduled visits, protocol-specified laboratory tests, other study procedures, and study restrictions - evidence of a signed informed consent/assent indicating that the subject is aware of the infectious nature of the disease and has been informed of the procedures to be followed, potential risks and discomforts, potential benefits, and other pertinent aspects of study participation