Which vaccine is not routinely given by the time of a 6-month well-child visit?

• A. Meningococcal polysaccharide vaccine (MPSV4).
• B. Haemophilus influenzae type B conjugate vaccine (Hib).
• C. Inactivated poliovirus vaccine (IPV).
• D. Diphtheria, tetanus, and acellular pertussis (DTaP).

Answer: (A)

Infants are immunized on a schedule that already covers several vaccines by six months, including Hib, IPV, and DTaP, with a possible HepB dose #3 and (depending on the brand) Rotavirus. The meningococcal polysaccharide vaccine is not part of routine infancy; it’s reserved for older children or adults at higher risk because young children respond poorly to polysaccharide antigens. By contrast, meningococcal vaccines given in adolescence are the conjugate type, not the polysaccharide one. So the vaccine not routinely given by the six‑month visit is the meningococcal polysaccharide vaccine.