• Man or non-pregnant / non-lactating woman between the ages of 50 years and 70 years at the time of enrollment into the study.

• Subjects who the investigator believes can and will comply with the requirements of the protocol (e.g., completion of the diary cards, return for follow-up visits).

• Subject who allow to access to their Medical Record.

• Subjects whose residence is in Taiwan who will remain available for the duration of the study, approximately 3 years following the first vaccination.

• Good general health as determined by physical examination, laboratory screening, and review of medical history.

• An informed consent form signed and dated by the subject.

• If the subject is female, she must be of non-childbearing potential, i.e. surgically sterilized or one year post-menopausal; or, if of childbearing potential, she must be abstinent or have used adequate contraceptive precautions (i.e. intrauterine contraceptive device; condom and spermicide combination, oral contraceptives or other equivalent hormonal contraception, e.g. progestin implantable, cutaneous hormonal patch or injectable contraceptives) for 30 days prior to vaccination, have a negative pregnancy test prior to vaccination and must agree to continue such precautions for 90 days after completion of the vaccination. For male subject, he must be abstinent or use a condom together with spermicide for 14 days after completion of the vaccination.