Evaluation of the Safety and Effectiveness of a Probiotic Bacterium to Boost the Immune Response to Influenza Vaccines

Inclusion Criteria: * Persons must be adult men and women aged 18-49 years (have not reached 50th birthday). * Persons must be able and willing to provide informed consent. * Persons must be willing to receive the influenza vaccine (Fluvax®) given as an intramuscular injection. * Persons must be willing to consume one gelatin capsule per day containing either probiotic bacteria or placebo (inactive substance) for the duration (42 days) of the study. * Persons must be willing to provide blood specimens, each of 10 ml, collected by venepuncture. * Persons must be willing to notify study personnel of a range of health effects by questionnaire. Exclusion Criteria: * Any health condition for which the influenza vaccine is not recommended including: chronic diseases of the pulmonary or cardiovascular systems (including asthma); chronic metabolic diseases (including diabetes); renal dysfunction; hemoglobinopathies; immune deficiency diseases (including HIV infection) or on-going immunosuppressive therapy. * Currently pregnant; nursing mothers; or planning a pregnancy within one month of vaccination. * Allergy to latex, egg, or egg protein, or the antibiotics neomycin or polymyxin. * A prior serious reaction to a vaccine, or have had Guillain-Barre syndrome. * Received an influenza vaccine in the past. * Received any other vaccine within one month prior to enrolment * Are participating in another research study involving any study medication