The purpose of this observational study is to determine whether the vaccine (UB 311), targeting the N-terminal amino acids (1-14) of the amyloid beta peptide, has long-term immunogenicity and efficacy in individuals diagnosed with mild or moderate Alzheimer's disease (AD) who previously received UB 311-treatment. Amyloid beta was selected as the target antigen based on supporting evidence of the hypothesis that places the accumulation of amyloid beta at the initiating step of AD.

Inclusion Criteria:

• Individuals with mild to moderate Alzheimer's disease who received three (3) injections of UB 311 in the initial Phase I V118-AD trial

Exclusion Criteria:

• Individuals with Alzheimer's disease who are currently on prohibited medications, have severe or uncontrolled systemic disease, or are unable or unwilling to comply with study protocol requirements.

Enrolled subjects who received UB 311-treatment in the initial UBI Protocol V118 (Protocol V118-AD) Phase I trial are eligible for continued follow-up to week 48