1) Male and female, 18-70 years old, 2) Severe patients (in any case: respiratory distress, RR >= 30 times / min, in resting state, oxygen saturation <= 93%, PaO2 / FiO2 <= 300MMHG), 3) Within 12 days after illness onset, 4) Agree to sign the informed consent, 5) Able to ingest, absorb and tolerate oral medication, 6) Agree to collect clinical samples, 7) Consent to contraceptive measures for sex within 7 days of the last oral medication.

1) Male and female, 18-70 years old, 2) Severe patients (in any case: respiratory distress, RR >= 30 times / min, in resting state, oxygen saturation <= 93%, PaO2 / FiO2 <= 300MMHG), 3) Within 12 days after illness onset, 4) Agree to sign the informed consent, 5) Able to ingest, absorb and tolerate oral medication, 6) Agree to collect clinical samples, 7) Consent to contraceptive measures for sex within 7 days of the last oral medication.