UMN-0501 is a purified recombinant influenza HA vaccine (A H5N1/Vietnam/1203/2004).

The purpose of the present study is to evaluate immunogenicity, safety and optimal dose among three different doses of UMN-0501 following two same-dose vaccinations of UMN-0501 per patient with a 3 week interval between vaccination in healthy young adults.

Immunogenicity will be confirmed by both microneutralization (MN) antibody and hemagglutination inhibition (HAI) titer levels in the serums of subjects after receiving different doses of UMN-0501. There will be three dose groups with 30 subjects per group for a total of 90 healthy young adults aged 20-40 years enrolled in this study.

Inclusion Criteria:

• Healthy adult as determined by medical history, physical examination, laboratory test, and clinical judgment of the investigator.
• Males and females aged 20-40 years.
• Provides signed informed consent form after received a detailed explanation of the study protocol prior to any study procedures.

Exclusion Criteria:

• Body Mass Index (BMI) 30 kg/m2 and above.
• Has a history of a A/H5N1 influenza virus infection and subjects had received other A/H5N1 influenza vaccine.
• Has a history of allergic reaction by food and medicine including vaccine, and acute fever illness (greater than 39.0C) within 2 days of vaccination.
• Has a history of Guillain-Barre syndrome or acute disseminated encephalomyelitis (ADEM).
• Has severe allergic diseases.
• Has asthma.
• Has a history of convulsions.
• Has a history of any serious disease.
• Known impairment of imune function.
• Known rheumatism and autoimmune disease.
• Receipt of medicines that would affect evaluation of immunogenicity.
• Receipt of any live virus vaccination or receipt of any inactivated vaccine/toxoid prior to enrollment.
• Blood donation prior to enrollment.
• Receipt of another investigation agent prior to enrollment.
• History of alcohol or drug abuse.
• Females who are pregnant or potentially childbearing or are breastfeeding.
• Ineligible subject based on the judgement of the investigator.