Immune Response of Intradermal and Intramuscular Preparations of Inactive Seasonal Influenza Vaccine in Older Age Group.

The consent form will be reviewed and signed by the participant prior to any study-related procedures.

Potential study participants will be assessed based on inclusion and exclusion criteria. Screening procedures, which include taking medical history, vital signs, random blood for dextrostix and vaccination will be performed on day 1.

A total of 220 participants will be randomized into 2 study arms, of which each group of 110 vaccinees will receive either seasonal intradermal influenza vaccine [group A] or seasonal intramuscular influenza vaccine [group B]. The randomization route of vaccination will be kept in concealed envelope at the study site. It will be open after subject signed informed consent form and all inclusion exclusion criteria met for enrollment. Groups A and B will receive the vaccine at day 1. Clinical activities for groups A and B during each visit (total of 5 visits). Blood will be drawn and assayed (for baseline assessment) using HAI (hemagglutination inhibition assay) to the three influenza strains.

Inclusion criteria

• Male or female aged ≥ 60 years
• Healthy and/or medically stable with controlled chronic medical conditions (e.g. diabetes mellitus, hypertension ) able to help oneself

Exclusion criteria

• Known history of systemic hypersensitivity to egg or chicken proteins or any of the vaccine components
• Influenza infection within the past 3 months
• History of Guillain Barre Syndrome (GBS) or brachial neuritis within 6 weeks of previous influenza vaccination
• Treatment with immunosuppressive or other immune-modifying drugs or cancer therapy within the past 6 months
• Any concomitant medication with aspirin
• Participation in other intervention study
• Incapacity to provide fully informed consent or be attentive to follow-up observations resulting from cognitive impairment, abuse of alcohol or drug addiction
• Random blood for Dextrostix more than 200 mg/dL