Rating Newest Oldest. Best Answer: The currently available meningococcal meningitis vaccine protects against four types of the bacterium Neisseria meningitidis, a very important cause of bacterial meningitis and sepsis in adolescents and young adults in the United States.ating Newest Oldest. Best Answer: The currently available meningococcal meningitis vaccine protects against four types of the bacterium Neisseria meningitidis, a very important cause of bacterial meningitis and sepsis in adolescents and young adults in the United States.