*1990s - conjugated vaccines for A and C after success of Hib conjugate vaccine
*2000s - monovalent A vaccine for Africa
**"MenAfriVac"[[file:Development history of meningococcal vaccine.jpg|500px]] ===current vaccines===*men C conjugate*A,C,Y,W135 *B-PS has potential toxicity for infant brain**B-PS showed interaction with fatal brain cells which suggests potential of causing neurological damage for young infants