On Jan. 14, 2005, the first meningococcal polysaccharide (Serogroups A, C, Y and W-135) diphtheria toxoid conjugate vaccine (Menactra by Sanofi Pasteur) was licensed. This marked the first meningococcal vaccine that was immunogenic and indicated for children younger than 2 years of age.

Neisseria meningitidis is the leading cause of bacterial meningitis in the United States and worldwide. A serogroup A/C/W-135/Y polysaccharide meningococcal vaccine has been licensed in the United States since 1981 but has not been used universally outside of the military.