Inclusion Criteria:
1. Participants who can comply with all scheduled assessment visits during the clinical trial period and who can be continuously monitored by the investigator through the provided contact information
2. Males or females aged 55 to 74 years at the time of consent
3. Participants and/or legally authorized representatives who are capable of providing written informed consent (signed in person in the presence of a witness)
4. Participants with either positive or negative QFT test results at the time of screening; QFT testing can be omitted in the following case: If participants have a documented history of a positive QFT test result, evidenced by submitted records or recorded in the EMR
5. Participants with negative HIV test results at the time of screening
6. Participants with a record of BCG vaccination or BCG scar directly
7. Participants who fall within the following range in physical measurements at the time of screening: 19 ≤ Body Mass Index (BMI) ≤ 33 (kg/m\^2) BMI and weight results are rounded to the nearest whole number.
8. Healthy participants or those with well-managed chronic diseases through medical history and clinical examination
9. Female participants must provide evidence at the screening visit (Visit 1) that they meet one of the following criteria to be considered non-fertile:
* Non-fertile: Defined as post-menopausal or other infertility conditions. Post-menopausal women: No menstrual periods for at least 12 months after stopping all external hormone treatments and over 55 years old. Documented irreversible surgical infertility such as hysterectomy, bilateral oophorectomy, or bilateral salpingectomy. However, tubal ligation is not permitted.
* Fertile: Women of childbearing potential who have not undergone sterilization must agree to use appropriate contraception during the investigational product administration period and for 6 months after the end of the investigational product administration. They must undergo a serum pregnancy test (β-hCG test) at the screening visit (Visit 1) and urine pregnancy tests (Urine-hCG test) at subsequent visits, with negative HCG results required.
10. Male participants can be enrolled under the following conditions: Men who have not undergone vasectomy must agree to use barrier contraception (e.g., condoms) and agree that both they and their partner will use appropriate contraception during the investigational product administration period and for 6 months after the end of the investigational product administration.
11. Participants who understand the clinical trial procedures, voluntarily decide to participate and sign the informed consent form
12. Participants recommended for tuberculosis prevention treatment who have been adequately informed about and understand latent tuberculosis chemoprophylaxis, and voluntarily agree to participate in the clinical trial while expressing non-consent to the chemoprophylaxis
Exclusion Criteria:
Participants who meet any of the following criteria must be excluded from enrollment.
1. Participants who are suspected of having tuberculosis, have a history of tuberculosis, are currently undergoing treatment for tuberculosis, are being treated for latent tuberculosis infection, or have a history of medication treatment for latent tuberculosis infection at the time of the Screening (Visit 1) or the first administration (Visit 2)
2. Participants who have received other investigational products or used unapproved drugs within 6 months prior to participating in the clinical trial or who plan to use them during the trial period
3. Participants who have previously received an investigational tuberculosis vaccine
4. Participants who test positive for HIV at the screening visit
5. Participants who test positive for HCV or who test positive for HBsAg and negative for HBsAb in HBV tests at the screening visit
6. Participants who are exposed to or will be exposed to investigational or non-investigational products during the clinical trial period or who participate in another clinical trial simultaneously
7. Participants who have received immunoglobulins and/or any blood products within 90 days before the first administration of the investigational product or plan to receive them during the clinical trial period
8. Pregnant or breastfeeding female
9. Participants with the following medical or psychiatric conditions that make it impossible to conduct the clinical trial as judged by the principal investigator:
* Participants with acute fever (an arbitrary body temperature of 38°C or higher at the time of randomization or within 24 hours before randomization), acute respiratory disease, or active infection.
* Participants with malignancies or a history of malignancies within the past 5 years.
* Participants with respiratory diseases: who have received treatment for acute exacerbation or moderate exacerbation of a respiratory condition within 2 years prior to the first administration of the investigational product. (Participants with a history of high-risk pulmonary diseases, such as silicosis, may be excluded at the investigator's discretion, regardless of the treatment period or even if the history is beyond the past 2 years. However, participants with controlled asthma or COPD stage 0 (at-risk) may participate with judgment of the principal investigator.)
* Participants with serious cardiovascular diseases: congestive heart failure, coronary artery disease, myocardial infarction, uncontrolled hypertension, etc.
* Participants with neurological diseases: epilepsy, seizures within 3 years before the first administration of the investigational products, migraines, strokes, encephalopathy, Guillain-Barre syndrome, etc.
* Participants with a history of COVID-19 infection within 90 days before the screening visit (confirmed positive by NAAT or rapid antigen test) or who have not recovered from COVID-19-related symptoms after being diagnosed with COVID-19 more than 90 days before the screening visit.
* Participants with autoimmune hypothyroidism, autoimmune diseases, immunodeficiency diseases.
* Participants with other clinically significant medical histories related to the hepatobiliary system, kidneys, endocrine system, urinary system, musculoskeletal system, etc., as judged by the principal investigator.
* Participants with a history of hereditary or idiopathic angioedema.
* Participants with a history of organ or bone marrow transplantation.
* Participants with a history of platelet-related or bleeding disorders, a history of significant bleeding or bruising following intramuscular injection or venipuncture, or who are receiving anticoagulants.
10. Participants who have received radiation therapy within 12 months before the first administration of the investigational product. However, those who have received radiation therapy to the lungs are excluded regardless of the time frame.
11. Participants who have surgery planned during the clinical trial period
12. Participants with a history of severe allergic reactions or anaphylaxis to vaccines or other allergens
13. Participants with clinically significant abnormal findings in laboratory tests, ECG, or chest X-ray at the screening visit as judged by the principal investigator to be unsuitable for participation. Participants with fibrotic nodular lesions on chest X-ray (indicative of spontaneously healed tuberculosis lesions without a history of tuberculosis treatment)
14. Participants who have chronically received immunosuppressants or other immunomodulatory drugs within 6 months before the first administration of the investigational product
* High-dose corticosteroids (continuous use of doses exceeding 15 mg/day of prednisolone for more than 14 days)
* However, topical steroids, nasal sprays, inhalers, and eye drops are allowed regardless of the dose
15. Participants who are deemed unsuitable for this clinical trial by the principal investigator for any other reasons
16. Participants with cognitive impairment.
17. Household contacts and close contacts who have been in an indoor environment with an active tuberculosis patient
* Household Contact: Family members and cohabitants who have been living in the same space or regularly interacting for at least 3 months.
* Close Contact: Individuals other than household contacts who have had direct contact in an enclosed indoor environment (e.g., classroom, office) for an extended period, defined as continuous or daily contact for at least 8 hours per day, or cumulative contact of 40 hours or more.
