A 6-month-old boy is brought to the clinic by his mother and grandmother for a routine well-child visit. The child was born full-term and has no medical problems. He recently learned to sit with support and is starting to eat pureed foods. Vital signs and physical examination are normal. As part of the routine pediatric immunization schedule, the pneumococcal conjugate vaccine is ordered. The patient's grandmother says that she recently received the pneumococcal polysaccharide vaccine. Which of the following statements is true regarding the difference between the pneumococcal conjugate and polysaccharide vaccines?

Question

A 6-month-old boy is brought to the clinic by his mother and grandmother for a routine well-child visit.  The child was born full-term and has no medical problems.  He recently learned to sit with support and is starting to eat pureed foods.  Vital signs and physical examination are normal.  As part of the routine pediatric immunization schedule, the pneumococcal conjugate vaccine is ordered.  The patient's grandmother says that she recently received the pneumococcal polysaccharide vaccine.  Which of the following statements is true regarding the difference between the pneumococcal conjugate and polysaccharide vaccines?

Quizplus · Accepted Answer

11ec160b_37af_76a3_9249_2f9af48e2487_MD0001_00 Streptococcus pneumoniae is a common cause of invasive infection (eg, meningitis, sepsis) in children, particularly those age <2. Routine childhood immunization has dramatically reduced the incidence of S pneumoniae infection in infancy. Pneumococcal strains are identified by the polysaccharide components of their capsule. These polysaccharides are included in vaccines to provide strain-specific immunity. The 2 types of pneumococcal vaccines are the polysaccharide and conjugate vaccines. The 23-valent pneumococcal polysaccharide vaccine (PPSV23, Pneumovax) protects against a wider range of serotypes (Choice E), but antibody levels decline over approximately 5 years. In addition, PPSV23 is not immunogenic in children age <2 due to their relatively immature humoral antibody response. Therefore, PPSV23 is recommended for all adults age >65 and for those age 2-64 with certain medical conditions (eg, diabetes, chronic pulmonary or cardiovascular disease). The 13-valent pneumococcal conjugate vaccine (PCV13, Prevnar) contains a nontoxic diphtheria protein conjugated to the polysaccharides that boosts the immune response through T cell recruitment. This conjugation allows for development of memory B cells, higher and longer-lasting antibody levels, and less mucosal carriage (herd immunity). Therefore, PCV13 is strongly immunogenic in infancy and part of routine childhood vaccinations. Similar to PPSV23, PCV13 is recommended for immunocompromised patients and adults age >65. (Choice A) The rate of local site reactions is similar between PCV13 and PPSV23, approximately 40%-50%. Most local site reactions are minor (eg, transient pain, redness, swelling). (Choice C) PPSV23 is a polysaccharide capsular subunit, not a live attenuated vaccine. Examples of live attenuated vaccines include the rotavirus, varicella, and measles-mumps-rubella vaccinations. (Choice D) Both PPSV23 and PCV13 provide strain-specific protection against invasive disease, including meningitis and sepsis. Educational objective: Pneumococcal conjugate vaccines are strongly immunogenic in infancy due to both B and T cell recruitment. They provide higher, longer-lasting antibody titers relative to pneumococcal polysaccharide vaccines. The pneumococcal polysaccharide vaccine is poorly immunogenic in infants due to their relatively immature humoral antibody response. __________ References: Impact of conjugate pneumococcal vaccines on the changing epidemiology of pneumococcal infections (http://www.ncbi.nlm.nih.gov/pubmed/21434802) A review of the evidence to inform pneumococcal vaccine recommendations for risk groups aged 2 years and older (http://www.ncbi.nlm.nih.gov/pubmed/24932959) Optimising the use of conjugate vaccines to prevent disease caused by Haemophilus influenzae type b, Neisseria meningitidis and Streptococcus pneumoniae. (http://www.ncbi.nlm.nih.gov/pubmed/18617296)

A 6-Month-Old Boy Is Brought to the Clinic by His