A single center, non-randomized clinical trial in two-dose primed healthy adults to evaluate the safety and immunogenicity of a booster dose of an inactivated pandemic influenza (H5N1) vaccine (whole-virion, aluminium-adjuvanted).

Inclusion Criteria:

• Had received two-dose priming vaccination in previous phase I trial
• Be able to show legal identity card for the sake of recruitment
• Be able to understand and sign the informed consent.

Exclusion Criteria:

• Woman： Who breast-feeding or planning to become pregnant during the study
• Any history of allergic reactions to vaccines or eggs
• Autoimmune disease or immunodeficiency
• Diabetes mellitus (type I or II), with the exception of gestational diabetes
• Serious angioedema episodes within the previous 3 years or requiring medication in the previous two years
• Hypertension that was not well controlled by medication or is more than 145/95 mmHg at enrollment
• Active malignancy or treated malignancy for which there is not reasonable assurance of sustained cure or malignancy that is likely to recur during the period of study
• Guillain-Barre Syndrome
• Women subjects with positive urinary pregnancy test
• Any history of immunosuppressive medications or cytotoxic medications or inhaled corticosteroids within the past six months
• History of any blood products administration within 3 months before the dosing
• Administration of any other investigational research agents within 30 days before the dosing
• Administration of any live attenuated vaccine within 30 days before the dosing
• Administration of subunit or inactivated vaccines, e.g. pneumococcal vaccine, or allergy treatment with antigen injections, within 14 days before the dosing
• Be receiving anti-TB prophylaxis or therapy currently
• Axillary temperature >37.0 centigrade at the time of dosing
• Psychiatric condition that precludes compliance with the protocol; past or present psychoses; past or present bipolar disorder requiring therapy that has not been well controlled on medication for the past two years; disorder requiring lithium; or suicidal ideation occurring within five years prior to enrollment
• Any medical, psychiatric, social condition, occupational reason or other responsibility that, in the judgment of the investigator, is a contraindication to protocol participation or impairs a volunteer's ability to give informed consent.