This study adopts a randomized, double-blind, placebo parallel control design, and is expected to include 120 eligible patients with severe novel coronavirus pneumonia.

Inclusion Criteria:

• Aged 18 to 80 years old (including threshold), regardless of gender;
• There is a history of novel coronavirus antigen- or nucleic acid-positive infection within 1 week;
• HRCT is consistent with the manifestation of viral pneumonia (judged by the investigator)
• Participants who voluntarily sign informed consent.

Exclusion Criteria:

• Participants who cannot take orally, or are suspected to be allergic to Jaktinib hydrochloride, similar drugs or their excipients, or have severe gastrointestinal dysfunction that affects drug absorption;

• Critical pneumonia patients with other organ failure requiring ICU monitoring and treatment;

• Participants who have received the following treatments within the specified time window before randomization:

  1. participants have received Janus kinase (JAK) inhibitor, interleukin 6 (IL-6) inhibitor, IL-1 inhibitor, tumor necrosis factor (TNF) inhibitor, T cell or B cell depletion agent, interferon and other immunosuppressive drugs within the first two weeks of randomization, except glucocorticoid;
  2. Systematically used CYP 3A4 potent inhibitor or potent inducer in the first five drug half lives at random;

• Immune deficiency;

• Participants who have received novel coronavirus vaccine within 1 week before randomization;

• Prior to randomization, there were the following active and uncontrolled infections: tuberculosis, HIV, syphilis, mycoplasma, chlamydia, parasites, and viral infections other than SARS CoV-2 that required systemic anti-infection treatment;

• Renal diseases requiring dialysis treatment;

• Pregnant and lactating women;

• Any other participants that were considered unsuitable by the investigator.