Immunogenicity and Safety of an Adjuvanted Inactivated Subunit Influenza Vaccine to Those of a Non-adjuvanted Inactivated Subunit Influenza Vaccine, When Administered to Adults Affected by Chronic Diseases

Inclusion Criteria: * 18 to 60 years of age adult volunteers, mentally competent, willing and able to give written informed consent prior to study entry, suffering from at least one of these chronic diseases:moderate to severe hypertension, moderate to severe congestive heart failure, chronic obstructive pulmonary disease (COPD) or moderate to severe asthma, moderate to severe hepatic or renal insufficiency, arteriosclerotic disease or insulin dependent diabetes mellitus Exclusion Criteria: * Hypersensitivity to ovalbumin, chicken protein, chicken feathers, influenza viral protein, neomycin or polymyxin or any other component of the vaccine; * History of neurological symptoms or signs, or anaphylactic shock following administration of any vaccine; * Known or suspected impairment/ alteration of immune function; * Any condition which might interfere with the evaluation of the study objectives