Ragweed Observational Study

Inclusion Criteria * Male or female, aged 18-65 years. * Reliable history of rhinoconjunctivitis and/or rhinoconjunctivitis plus controlled asthma on exposure to ragweed allergen for at least 2 years and required symptomatic treatment for at least 1 year. * Positive skin prick test (SPT) to Ambrosia artemisiifolia * Specific Immunoglobulin E (IgE) against Ambrosia artemisiifolia \>0.35 kU/L Exclusion Criteria * Positive skin test to any confounding, co-existing seasonal allergens likely to be present during the Pre-season baseline and ragweed pollen periods (grasses, miscellaneous weeds, fall trees) and who have received medication for these confounding seasonal allergies. * Medical records of symptomatic perennial allergic rhinitis and/or asthma due to an allergen to which the subject is regularly exposed (moulds, dust mites, cockroaches, and animal dander) and have received medication for these perennial allergies * Subjects with a history of severe drug allergy, severe angioedema or anaphylactic reaction to food or previous SPT for any allergen. * Subjects with a history of any significant disease or disorder (e.g., cardiovascular, pulmonary, gastrointestinal, liver, renal, neurological, immunopathological, musculoskeletal, endocrine, metabolic, malignant, psychiatric, major physical impairment) which, in the opinion of the Investigator, may influence the subject's ability to participate in this study.