The currently available stock of smallpox vaccine would be insufficient in the face of an incident of smallpox attack. Thus, new manufacturing methods for smallpox vaccine are urgently needed because previous manufacturing methods using calf lymph are no longer acceptable in the view of current standards. Recently, CJ corporation in Republic of Korea has developed cell-culture derived smallpox vaccine (CJ-50300) which was manufactured by infecting MRC-5 cells. The aim of this clinical trial were to assess safety, reactogenicity, and immunogenicity of CJ-50300.

Inclusion Criteria:

1. Healthy Korean male and female subjects between 20 and 60 years of age at the time of screening visit
2. Willing to participate and have signed the informed consent form
3. In good general health, without clinically skin diseases history, physical examination or laboratory test results
4. Hematocrit > 33% for women; > 38% for men
5. White cell count 3,300-12,000/mm3
6. Total lymphocyte count > 800 cells/mm3
7. Subjects who have never been vaccinated with smallpox vaccines

Exclusion Criteria:

1. Diseases or conditions that cause immunodeficiency (For examples; HIV AIDS, leukemia, lymphoma, generalized malignancy, agammaglobulinemia, history of transplantation, therapy with alkylating agents, antimetabolites, radiation, or oral or parenteral corticosteroids).
2. In close physical contact (household or at work) with an individual who has the diseases or conditions that cause immunodeficiency
3. History or present of eczema or atopic dermatitis
4. Allergy or sensitivity to any known components of vaccine or other medicines
5. In close physical contact (household or at work) with an individual who has acute or chronic skin conditions such as dermatitis, exfoliative dermatitis
6. Subjects requiring steroid therapy
7. Subjects who are taking immunosuppressive therapy
8. Subjects who are planning for blood donations
9. Autoimmune disease such as lupus erythematosus
10. Subjects who work in medical institution
11. Household contacts with women who are pregnant or breast-feeding
12. Female subjects who are pregnant or breast-feeding and have positive result by serum pregnancy test or urine pregnancy test, or do not using approved contraceptives such as sterilization, contraceptive ring injectable, combined oral contraceptive pills and barrier contraceptive, combined hormone-based therapy, contraceptive cream, contraceptive jelly, diaphragm or condoms
13. Subjects household member < 1 year old or work with children < 1 year old
14. Subjects with a known history of Cardiac disease or have three or more of the following risk factors: hyperpiesia, obesity, hyperlipidemia, glucosuria, sclerosis, cerebral arteriosclerosis
15. Receipt of immunoglobulin and steroid within 14 days of vaccination
16. Receipt of investigational research agents within 120 days of vaccination
17. HBsAg seropositive
18. HCV antibody seropositive
19. HIV seropositive
20. Subjects having fever (oral temperature > 38℃) or severe nutrition disorder
21. Blood donation within 12 weeks in advance screening visit
22. Subject who are not suitable to participate in study according to investigator's judgement

28 days, 3 months, 6 months

In the Conventional-dose Group, all 82 finished the 28 day follow up, 80 were available for 3 months, and 77 were available for the 6 months safety assessment.

In the Low-dose Group, all 41 finished the 28 day follow up, 40 were available for 3 months, and 39 were available for the 6 months safety assessment.

the study was limited to vaccinia-naïve adults, thus yielding no data concerning the efficacy of CJ-50300 in non-naïve adults or in children.