The study is designed in two phases: single-dose administration and multiple-dose administration. A randomized, double-blind, placebo-controlled trial design was used to evaluate the safety, tolerability, pharmacokinetic characteristics and immunogenicity of TQC2938 injection in healthy adults.

Inclusion Criteria:

• Sign informed consent before the study to fully understand the purpose, process and possible adverse reactions of the test.
• Adults aged between 18 and 60 years (inclusive)，both male and female;
• The male subject should weigh at least 50kg, the female subject should weigh at least 45kg. And body mass index (BMI) within 18~28 kg/m2 (inclusive);
• The subjects were able to communicate well with the investigators, voluntarily and were able to understand and follow the protocol to complete the study;
• Female patient had no plans to become pregnant for 6 months from the date of signing the informed consent to the last dose, and must use effective non-drug contraception with their sexual partners of childbearing age。

Exclusion Criteria:

• Pregnant or lactating women;
• Past medical history or current cardiac, endocrine, metabolic, renal, hepatic, gastrointestinal, skin, infection, hematological, neurological or psychiatric diseases/abnormalities, or related chronic abnormalities, or related chronic diseases, or acute diseases, and the investigator evaluated that the subject was not suitable for the trial;
• People who have abnormal and clinically significant results in vital signs, physical examination, laboratory tests, 12-lead electrocardiogram (ECG) and Chest radiograph during screening period;
• Subjects Positive for Any of Hepatitis B Virus Surface Antigen (HBsAg), Hepatitis C Virus Antibody (Anti-HCV), Human Immunodeficiency Virus Antibody (Anti-HIV), and Treponema Pallidum Antibody (Anti-TP);
• A history of clinically significant infections, including upper respiratory tract infections (URTI) and lower respiratory tract infections (LRTI), occurred within 30 days prior to and during screening and required antibiotic or antiviral treatment;
• Had undergone surgery within 8 weeks prior to screening period or expected to undergo surgery during the study period;
• Participated in any clinical trial within 3 months prior to the screening period;
• Received immunoglobulins or blood products within 30 days prior to randomization;
• Blood donation or significant blood loss of more than 400 mL within 3 months prior to randomization, or plan to donate blood within 3 months;
• Potential blood collection difficulties, can not tolerate venipuncture or have a history of fainting needles and fainting blood;
• A history of allergic reaction to treatment with another therapeutic monoclonal antibody or biologics, a history of any well-defined drug or food allergy, especially to ingredients similar to the drug in this trial;
• Those who received or planned to receive inactivated or active vaccines within 30 days prior to randomization or throughout the study period, including the follow-up period；
• Those who smoked more than 5 cigarettes/day or used a comparable amount of nicotine or nicotine-containing products in the 6 months prior to randomization, or could not stop using any tobacco products during the trial period；
• People with chronic alcohol abuse or who drank more than 14 units of alcohol per week in the 3 months prior to screening (1 unit =360 mL beer or 45 mL spirits with 40% alcohol or 150 mL wine), or who could not abstain during the test period, or who tested positive for alcohol breath；
• History of drug abuse or a positive result of urine drug test at screening;
• Received any marketed or investigational biological agent (other than vaccines) within 4 months or 5 half-lives (whichever is older) prior to randomization；
• Any prescription, over-the-counter, and herbal medicines, except vitamin products, were taken in the 4 weeks prior to randomization；
• Use of any systemic cytotoxicity or systemic immunosuppressants within 6 months prior to randomization or during the study period, or any local cytotoxin or local immunosuppressive drug within 30 days or 5 half-life periods (whichever is longer) prior to randomization or during the study period；
• Any situation in which the investigator believes that this poses a safety risk to the subject in the trial or may interfere with the conduct of the study, or that the investigator believes that the subject may not be able to complete the study or may not be able to comply with the requirements of the study.