The spread of Influenza H1N1 has prompted the development of vaccines against this virus. IBD patients are at increased risk of developing complications of Influenza H1N1. The efficacy and safety of H1N1 vaccination have not been evaluated in this population of patients. We would like to estimate the efficacy and safety of vaccination against influenza H1N1 in patients with IBD who treated with immunomodulatory drugs.

200 patients with IBD and 200 healthy subjects will participate in the study. All the subjects will be vaccinated with Focetria (Novartis) and will be evaluated the day of vaccination and 4 weeks later.

The evaluation will include:

Efficacy of the vaccine: Blood will be drawn on day 0 and 4 weeks later and tested for the presence of antibodies against A/California17/2009/H1N1 by hemagglutination inhibition test.

Safety of the vaccine:

• Records of adverse event
• Assessment of disease activity : CDAI and MAYO score

Inclusion Criteria:

1. Patients suffering from IBD (inflammatory bowel disease): UC/ CD
2. Able to firm an informed consent
3. Aged - 18-65
4. Candidates to receive vaccination against H1N1, according to the recommendation of the Ministry of Health
5. patients who treated with immunomodulators and biologics

Exclusion Criteria:

1. Allergy to eggs
2. Known allergy to seasonal influenza vaccine
3. Pregnant women
4. Patients who inoculate another vaccine in the past 3 weeks (except vaccine fot seasonal influenza
5. Patients without worsening in their disease condition (stable condition)