1. suspected or confirmed pregnancy at evaluation 2. severe decompensation of any of the patient's underlying diseases 3. previous diagnosis of covid-19 with complete resolution of symptoms for at least 2 days. 4. patients meeting criteria for severe or critical covid-19 at evaluation: 1. severe covid-19 - patient with ≥1 of the following: tachypnea (≥30 breaths per minute), peripheral oxygen arterial saturation (sao2) less than or equal to 93% (89% in mexico city and guadalajara) with a maximum 3 l/min of supplementary oxygen (patients requiring ≥4 l/min will be considered to have progressed to severe covid-19), or pao2/fio2 ratio \<300. 2. critical covid-19 - patient with ards, shock, multiorgan failure, or any other condition requiring admission to an intensive care unit. elimination criteria: 1. participant retires consent to participate in the study 2. patient requiring ≥4 l/min of supplementary oxygen in the 24 hours of hospitalization (in the case that randomization occurred in the first 24 hours of hospitalization) 3. two negative tests against sars-cov-2 (a sequential diagnostic strategy will be implemented to reduce losses due to false negative tests). 4. patient that do not tolerate thermotherapy and requests to stop receiving the intervention. 5. transfer to another medical unit in the first 5 days of inclusion in the study.

1. suspected or confirmed pregnancy at evaluation 2. severe decompensation of any of the patient's underlying diseases 3. previous diagnosis of covid-19 with complete resolution of symptoms for at least 2 days. 4. patients meeting criteria for severe or critical covid-19 at evaluation: 1. severe covid-19 - patient with ≥1 of the following: tachypnea (≥30 breaths per minute), peripheral oxygen arterial saturation (sao2) less than or equal to 93% (89% in mexico city and guadalajara) with a maximum 3 l/min of supplementary oxygen (patients requiring ≥4 l/min will be considered to have progressed to severe covid-19), or pao2/fio2 ratio \<300. 2. critical covid-19 - patient with ards, shock, multiorgan failure, or any other condition requiring admission to an intensive care unit. elimination criteria: 1. participant retires consent to participate in the study 2. patient requiring ≥4 l/min of supplementary oxygen in the 24 hours of hospitalization (in the case that randomization occurred in the first 24 hours of hospitalization) 3. two negative tests against sars-cov-2 (a sequential diagnostic strategy will be implemented to reduce losses due to false negative tests). 4. patient that do not tolerate thermotherapy and requests to stop receiving the intervention. 5. transfer to another medical unit in the first 5 days of inclusion in the study.

suspected or confirmed pregnancy at evaluation severe decompensation of any of the patient's underlying diseases previous diagnosis of covid-19 with complete resolution of symptoms for at least 2 days. patients meeting criteria for severe or critical covid-19 at evaluation: severe covid-19 - patient with ≥1 of the following: tachypnea (≥30 breaths per minute), peripheral oxygen arterial saturation (sao2) less than or equal to 93% (89% in mexico city and guadalajara) with a maximum 3 l/min of supplementary oxygen (patients requiring ≥4 l/min will be considered to have progressed to severe covid-19), or pao2/fio2 ratio <300. critical covid-19 - patient with ards, shock, multiorgan failure, or any other condition requiring admission to an intensive care unit. elimination criteria: participant retires consent to participate in the study patient requiring ≥4 l/min of supplementary oxygen in the 24 hours of hospitalization (in the case that randomization occurred in the first 24 hours of hospitalization) two negative tests against sars-cov-2 (a sequential diagnostic strategy will be implemented to reduce losses due to false negative tests). patient that do not tolerate thermotherapy and requests to stop receiving the intervention. transfer to another medical unit in the first 5 days of inclusion in the study.

suspected or confirmed pregnancy at evaluation severe decompensation of any of the patient's underlying diseases previous diagnosis of covid-19 with complete resolution of symptoms for at least 2 days. patients meeting criteria for severe or critical covid-19 at evaluation: severe covid-19 - patient with ≥1 of the following: tachypnea (≥30 breaths per minute), peripheral oxygen arterial saturation (sao2) less than or equal to 93% (89% in mexico city and guadalajara) with a maximum 3 l/min of supplementary oxygen (patients requiring ≥4 l/min will be considered to have progressed to severe covid-19), or pao2/fio2 ratio <300. critical covid-19 - patient with ards, shock, multiorgan failure, or any other condition requiring admission to an intensive care unit. elimination criteria: participant retires consent to participate in the study patient requiring ≥4 l/min of supplementary oxygen in the 24 hours of hospitalization (in the case that randomization occurred in the first 24 hours of hospitalization) two negative tests against sars-cov-2 (a sequential diagnostic strategy will be implemented to reduce losses due to false negative tests). patient that do not tolerate thermotherapy and requests to stop receiving the intervention. transfer to another medical unit in the first 5 days of inclusion in the study.

1. suspected or confirmed pregnancy at evaluation 2. severe decompensation of any of the patient's underlying diseases 3. previous diagnosis of covid-19 with complete resolution of symptoms for at least 2 days. 4. patients meeting criteria for severe or critical covid-19 at evaluation: 1. severe covid-19 - patient with ≥1 of the following: tachypnea (≥30 breaths per minute), peripheral oxygen arterial saturation (sao2) less than or equal to 93% (89% in mexico city and guadalajara) with a maximum 3 l/min of supplementary oxygen (patients requiring ≥4 l/min will be considered to have progressed to severe covid-19), or pao2/fio2 ratio <300. 2. critical covid-19 - patient with ards, shock, multiorgan failure, or any other condition requiring admission to an intensive care unit. elimination criteria: 1. participant retires consent to participate in the study 2. patient requiring ≥4 l/min of supplementary oxygen in the 24 hours of hospitalization (in the case that randomization occurred in the first 24 hours of hospitalization) 3. two negative tests against sars-cov-2 (a sequential diagnostic strategy will be implemented to reduce losses due to false negative tests). 4. patient that do not tolerate thermotherapy and requests to stop receiving the intervention. 5. transfer to another medical unit in the first 5 days of inclusion in the study.

1. suspected or confirmed pregnancy at evaluation 2. severe decompensation of any of the patient's underlying diseases 3. previous diagnosis of covid-19 with complete resolution of symptoms for at least 2 days. 4. patients meeting criteria for severe or critical covid-19 at evaluation: 1. severe covid-19 - patient with ≥1 of the following: tachypnea (≥30 breaths per minute), peripheral oxygen arterial saturation (sao2) less than or equal to 93% (89% in mexico city and guadalajara) with a maximum 3 l/min of supplementary oxygen (patients requiring ≥4 l/min will be considered to have progressed to severe covid-19), or pao2/fio2 ratio <300. 2. critical covid-19 - patient with ards, shock, multiorgan failure, or any other condition requiring admission to an intensive care unit. elimination criteria: 1. participant retires consent to participate in the study 2. patient requiring ≥4 l/min of supplementary oxygen in the 24 hours of hospitalization (in the case that randomization occurred in the first 24 hours of hospitalization) 3. two negative tests against sars-cov-2 (a sequential diagnostic strategy will be implemented to reduce losses due to false negative tests). 4. patient that do not tolerate thermotherapy and requests to stop receiving the intervention. 5. transfer to another medical unit in the first 5 days of inclusion in the study.

- critical ill patients with assisted ventilation - patients with clinical sepsis symptoms

- critical ill patients with assisted ventilation - patients with clinical sepsis symptoms