The purpose of this explorative trial is to collect preliminary data on efficacy and safety of thymosin alpha 1 given at different doses as an adjuvant to egg-derived H1N1sw monovalent influenza vaccine in hemodialysis patients. The final aim is that of gathering information needed for planning a following confirmatory study on the efficacy and safety of Thymosin alpha 1 in the same indication.

The emergence and spread of the novel influenza A (H1N1) virus has been of great concern globally.

Uremic patients are especially vulnerable to infections and it is generally recommended to vaccinate patients with chronic renal insufficiency yearly against influenza. In patients on haemodialysis (HD) the vaccination response has been considered suboptimal.

Decreased antibody response to T-cell dependent antigens may be one factor that accounts for insufficient efficacy of certain vaccination programs (eg, influenza). Diminished antibody responses have also been reported in patients with end-stage renal disease. The evidence for impairment of cell-mediated immunity in hemodialysis patients has been attributed to incompetence in T-cell-mediated immune responses.

Since Zadaxin can enhance T-cell-dependent specific antibody production, the addition of Zadaxin (Thymosin alpha 1)to vaccination programs for immunocompromised individuals should be effective.

Inclusion Criteria:

1. Signed written informed consent.
2. Age > 18 .
3. Chronic dialysis for ESRD .
4. Life expectancy of at least 6 months.

Exclusion Criteria:

1. They have any serious disease
2. They are hypersensitive to eggs, chicken protein, chicken feathers, influenza viral protein, neomycin or polymyxin or any other component of the vaccine.
3. They have a history of neurological symptoms or signs, or anaphylactic shock following administration of any vaccine.
4. Within the past 3 days, they have experienced fever (i.e., axillary temperature _ 38°C).
5. They have any condition which, in the opinion of the investigator, might interfere with the evaluation of the study objective.