A Clinical Trial Evaluating the Monkeypox Recombinant Protein Vaccine

This study is a randomized, double-blind, placebo-controlled Phase I clinical trial representing the first-in-human (FIH) investigation of the Monkeypox recombinant protein vaccine JT118. The primary objectives are to evaluate the safety, tolerability, and immunogenicity of two doses of JT118 in healthy adults and to conduct preliminary exploration of vaccination regimens. The study will sequentially proceed from the low-dose group to the high-dose group with Subgroup 1 (participants without prior Smallpox vaccination history) and Subgroup 2 (participants with prior Smallpox vaccination history) being conducted concurrently within each dose group. It will explore single-dose, two-dose, and three-dose vaccination regimens with approximately 180 healthy adult participants planned for enrollment.

Inclusion Criteria: 1. Male or female participants aged 18 to 59 years (inclusive) at the time of signing the informed consent form. 2. Participants with fertility (including male participants) and their spouses are willing to avoid pregnancy (including sperm donation and egg donation plans) from 14 days before screening until six months after the last administration of the investigational vaccine, and are willing to use effective contraception. 3. Ability to understand the study procedures, sign a written informed consent form, and complete the study according to the protocol requirements. 4. Body temperature \