Test ID: PN7    
Streptococcus pneumoniae IgG Antibodies, 7 Serotypes, Serum

Assessing the response to active immunization with Prevnar pneumococcal 7-valent conjugate vaccine

Streptococcus pneumoniae causes infectious diseases in children and adults, including invasive infections (eg, bacteremia and meningitis) and infections of the respiratory tract (eg, pneumonia and otitis media).(1,2) Streptococcus pneumoniae is responsible for approximately 40,000 deaths and 500,000 cases of pneumonia annually in the United States.

There are more than 90 serotypes of Streptococcus pneumoniae. The serotypes responsible for disease vary with age and geographic location. In children younger than 6 years, 7 serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F) account for 80% of invasive disease and up to 100% of all isolates that are highly resistant to treatment with penicillin.(3,4)

The greatest risk of invasive infection with Streptococcus pneumoniae occurs in children <2 years of age; and active immunization with conjugate vaccine is recommended to prevent invasive infections caused by Streptococcus pneumoniae.(5) Bacterial polysaccharides elicit antibodies in children by a T-cell-independent mechanism, and immune responses to polysaccharide antigens such as Streptococcus pneumoniae are generally poor in children <2 years, requiring multiple injections of vaccine prepared from purified polysaccharides conjugated to an immunogenic carrier (Corynebacterium diphtheria strain C7 protein). The recommended vaccine for children <2 years (Prevnar) contains the 7 serotypes mentioned above and is administered in 4 doses. The vaccine is highly effective in preventing invasive disease in children with reported efficacy of 88% to 100%.

Results are reported in mcg/mL.

Serotype results within the normal value range are consistent with a normal humoral immune response to 7-valent conjugate vaccine.

Published data are available from efficacy studies that define the geometric mean concentrations and the 95% confidence intervals for children after 3 and 4 doses of the vaccine.(6)

Concentrations of IgG antibodies to Streptococcus pneumoniae serotypes greater than the lower limits of the 95% confidence intervals are consistent with a normal humoral immune response to 7-valent conjugate vaccine.

The minimum concentration of IgG antibody necessary to insure protection against invasive disease has not been determined for any serotype of Streptococcus pneumoniae.

Serotype specific antibodies may persist for up to 10 years following immunization or infection.

The humoral immune response to Streptococcus pneumoniae is age-dependent and the database of IgG antibody concentrations to different serotypes is incomplete.

1. Schuchat A, Robinson K, Wenger JD, et al: Bacterial meningitis in the United States in 1995. N Engl J Med 1997;337:970-976

2. Zangwill KM, Vadheim CM, Vannier AM, et al: Epidemiology of invasive pneumococcal disease in Southern California: implications for the design and conduct of a pneumococcal conjugate vaccine efficacy trial. J Infect Dis 1996;174:752-759

3. Butler JC, Breiman RF, Lipman HB, et al: Serotype distribution of Streptococcus pneumoniae infections among preschool children in the United States, 1978-1994: implications for development of a conjugate vaccine. J Infect Dis 1995;171:885-889

4. Butler JC, Hoffman J, Cetron MS, et al: The continued emergence of drug-resistant Streptococcus pneumoniae in the United States. An update from the Centers for Disease Control and Prevention's Pneumococcal Sentinel Surveillance System. J Infect Dis 1996;174:986-993

5. Jacob GL, Homburger HA: Simultaneous Quantitative Measurement of IgG Antibodies to Streptococcus Pneumoniae Serotypes by Microsphere Photometry. J Allergy Clin Immunol,2004;113(2) Suppl (Abstract 1049, pS288)

6.Table 2: Geometric mean concentrations (ug/mL) of pneumococcal antibodies following the third and fourth doses of Prevnar or control when administered concurrently with DTP-HbOC in the efficacy study. In Physician's Desk Reference 2003. 57th edition. Montvale, NJ, Thompson PDR, p 3455

7. Plikaytis BD, Holder PF, Pais LB, et al: Determination of parallelism and nonparallelism in bioassay dilution curves. J Clin Microbiology 1994 October;32:2441-2447

8. Plikaytis BD, Goldblatt D, Frasch CE, et al: An analytical model applied to a multicenter pneumococcal enzyme-linked immunosorbent assay study. J Clin Microbiology 2000 June;38(6):2043-2050