Compare Dose Regimens of AllerT, in Adults With Allergic Rhino-Conjunctivitis to Birch Pollen Studied in EEC

Inclusion Criteria: * Minimum two-year history of moderate to severe rhino-conjunctivitis on exposure to birch pollen with a need to take symptomatic medications (antihistamine, steroid) during pollen season, prior to study enrollment. * Sensitivity to birch tree pollen confirmed at Screening by both of the following criteria: * Positive Skin Prick Test (SPT) to birch pollen extract (wheal ≥ 3 mm than the negative control). Negative control must be ≤ 2 mm. * Positive specific IgE CAP test for Bet v 1 (≥ 0.7 kU/L). * A qualifying score in at least one of the two Baseline EEC Challenges: at least one diary card of 12/24 or greater for Total Rhinoconjunctivitis Symptom Score (TRSS) as well as either one diary card 6/12 or greater for Total Nasal Symptom Score (TNSS) or Total Ocular Symptom Score (TOSS). Exclusion Criteria: * Positive SPT to AllerT (wheal ≥ 3 mm than the negative control). * Received specific immunotherapy against: * Any allergen within three years before the Screening visit. * Birch tree pollen or a tree pollen mix including birch pollen at any time before the Screening visit. * Clinically significant symptoms due to allergens other than birch pollen during the EEC challenge periods (eg, perennial allergies, allergies to other pollens with overlapping allergy seasons during the EEC periods). * Persistent un-controlled asthma; subjects with a Forced Expiratory Volume (FEV1) lower than 80% of their predicted value and/or subjects under chronic treatment for asthma with regular use of inhaled steroids. Subjects with seasonal asthma may be included. Subjects who require the occasional use of inhaled broncho-dilator can be included. * History of birch pollen induced asthma. Note: A diagnosis of isolated exercise induced bronchospasm or controlled asthma (Global Initiative for Asthma \[GINA\] Step 1) not triggered by birch pollen does not constitute an exclusion criterion. * History of documented severe anaphylactic reaction (Grade 4 of World Allergy Organization \[WAO\]). * History of sinus disease including: * Acute or significant chronic sinusitis. * History of significant recurrent acute sinusitis, defined as two episodes per year for the last two years, all of which required antibiotic treatment. * History of chronic sinusitis, defined as sinus symptoms lasting greater than 12 weeks that includes two or more major factors or one major factor and two minor factors. Major factors are defined as facial pain or pressure, nasal obstruction or blockage, nasal discharge or purulence or discolored postnasal discharge, purulence in nasal cavity, or impaired or loss of smell. Minor factors are defined as headache, fever, halitosis, fatigue, dental pain, cough, and ear pain, pressure, or fullness. * Subjects who cannot tolerate the Baseline EEC Challenge or do not meet the Baseline EEC Challenge inclusion criteria. * Subjects with a history of immunodeficiency or any other conditions that might affect the subject's safety or interpretation of study results. * Received immunosuppressive medication (including oral corticosteroids) within four weeks prior to Screening, or planned to be used during the trial period. * Received systemic or local antihistamines, oral or inhaled corticosteroids or under antidepressant medication with antihistamine effects within two weeks prior to Screening. * Subjects for whom administration of epinephrine is contraindicated (eg, subjects with acute or chronic symptomatic coronary heart disease or severe hypertension). * Subjects being treated with beta-blockers in any form including topical ocular beta-blocker type medication.