Pfizer Inc. PFE, -0.09% on Thursday announced positive results from a late-stage trial of a meningococcal vaccine candidate called MenABCWY in adolescents and said it will submit an application for approval to the U.S. Food and Drug Administration in the fourth quarter. Meningococcal disease is a relatively rare but serious illness caused by a bacteria that can cause meningitis and can lead to death within 24 hours of infection. The current vaccination recommendations in the U.S. for adolescents and young adults are for a MenACWY vaccine and a separate MenB vaccine for a total of four doses, although less than a third of adolescents get even one dose. Pfizer is aiming to simplify the schedule by reducing the number of doses needed for maximum protection. The Phase 3 trial met all primary and secondary endpoints for the five serogroups that cause the majority of cases of the disease. Pfizer shares were flat premarket but have fallen 25% in the year to date, while the S&P 500 SPX, +0.34% has fallen 17%.