An 18-Month-Old, Partially Vaccinated Boy Is Brought to the Office

An 18-month-old, partially vaccinated boy is brought to the office for a routine well-child examination.  His parents have elected a delayed schedule for vaccine administration based on personal preferences.  Today, the patient is scheduled to receive the Haemophilus influenzae serotype b (Hib) conjugate vaccine.  The parents are given detailed information about the vaccine, but the mother asks, "Why is 'tetanus toxoid conjugate' listed on the package insert?"  She adds that her son already received the diphtheria-tetanus-acellular pertussis (DTaP) vaccine.  The parents request an explanation for the reason the Hib vaccine contains both the capsular polysaccharide of Hib as well as the conjugated tetanus toxoid.  Which of the following best describes the purpose of Hib vaccine conjugation?

A) Decreases adverse vaccine reactions
B) Elicits T cell-dependent immune response
C) Eliminates the need for booster doses
D) Induces immunity against nontypeable H influenzae
E) Induces immunity against the conjugated toxoid