This study is a randomized, parallel-group, open-label Phase I clinical trial designed to compare the bioavailability and safety of subcutaneous SHR-1819 injection administered via different injection devices in healthy subjects.

Inclusion Criteria:

1. Understanding the research procedures and methods, being able to complete the research in accordance with the procedure requirements, and sign the informed consent;
2. The age on the date of signing the informed consent must be ≥18 years old and ≤55 years old;
3. Body mass index (BMI) at screening period must be ≥19.0 kg/m2 and <26.0 kg/m2, weight of male must≥ 50.0 kg and <80.0 kg;
4. The subjects and their female partners are willing to have no reproductive plan from signing the informed consent to 3 months after the last administration of the study drug, and voluntarily take effective contraceptive measures and do not plan to donate sperm or ovum.

Exclusion Criteria:

1. History of the following diseases or treatments: (1) Receipt of a live-attenuated vaccine within 1 month prior to screening or planned receipt during the study; (2) Previous participation in a clinical trial involving any investigational product (drug or device) within 3 months before screening; (3) History of food or drug allergy or atopic allergic disease (asthma, urticaria);
2. Any one of the following tests at Screening period or Baseline period: (1) Human immunodeficiency virus antibody (HIV-Ab), syphilis serological examination, hepatitis B virus surface antigen (HBsAg), hepatitis C virus antibody (HCV-Ab) positive; (2) Exclude individuals who have experienced severe trauma or undergone major surgery within the past 6 months, or who plan to undergo surgery during the trial period;
3. General situation: (1) Have a history of drug use or drug abuse; (2) Investigators, site staff, or any other individuals directly involved in the conduct of the protocol;
4. Subjects who are considered by the investigator to have any other factors which are not suitable for participating in this study.