Efficacy and Safety of Grass Sublingual Tablet in Adults (P05238 AM3)(COMPLETED)

This is a multicenter, double-blind, randomized, placebo-controlled, parallel-group study in participants 18 to 65 years of age, of either sex, and of any race with a history of grass pollen induced rhinoconjunctivitis with or without asthma. While receiving treatment, participants will receive either grass sublingual tablet or placebo. Open-label rescue medications for the hinoconjunctivitis and asthma symptoms will be provided. Participants will visit the study site for at least 12 visits. A total of 10 allergic symptoms, 6 rhinoconjunctivitis and 4 lung symptoms, will be recorded daily on an electronic diary by the participant. The start and end of the grass pollen season (GPS) was determined based on the regional grass pollen count, and lasted up to 162 days. For each region, the GPS is defined as the first day of 3 consecutive recorded days with a grass pollen count of ≥ 10 grains/m\^3, to the last day of the last occurrence of 3 consecutive recorded days with a grass pollen count ≥ 10 grains/m\^3, inclusively.