<prompt> Bivalent meningococcal vaccine is ?A YA CC yA W-I35  <response>: Ans. is b i.e., A C Two type of meningococcal vaccine develop Unconjugated polysaccharide vaccine. Conjugated group C vaccine. Polysaccharide vaccines Internationally marketed meningococcal polysaccharide vaccines are o Bivalent A and C, Trivalent A, C and W-135 Tetravalent A, C, Y and W-135. The vaccines are purified, heat-stable, lyophilized capsular polysaccharides from meningococci of the respective serogroups. A protective antibody response occurs within 10 days of vaccination. In schoolchildren and adults, one dose of these polysaccharide vaccines appears to provide protection for at least 3 years, but in children under 4 years of age the levels of specific antibodies decline rapidly after 2-3 years. 