SA1211 Injection Phase 1 Study

The goal of this clinical trial is to evaluate the safety, tolerability, immunogenicity and Pharmacokinetics (PK) characteristics of SA1211 Injection in healthy volunteers (Part A) and participants with chronic hepatitis B (CHB, Part B), and assess its preliminary efficacy in participants with chronic hepatitis B (CHB). The main questions it aims to answer are: What are the safety, tolerability, immunogenicity and PK characteristics of a single subcutaneous injection of SA1211 Injection in healthy volunteers (Part A)? What are the safety, tolerability, immunogenicity and PK characteristics of multiple subcutaneous injections of SA1211 Injection in participants with CHB (Part B)? What is the preliminary efficacy of SA1211 Injection in participants with CHB (Part B)? Participants will: * Part A (healthy volunteers): Receive a single subcutaneous injection of SA1211 Injection or placebo and complete relevant safety, tolerability and PK monitoring as required. * Part B (participants with CHB): Receive multiple subcutaneous injections of SA1211 Injection or placebo and complete relevant safety, tolerability, PK monitoring and preliminary efficacy assessment as required.