Reference Values

Humoral Immunity Evaluation

Diphtheria Antitoxoid

Reference Range:  ≥0.01 IU/mL (Post-Vaccination)

Interpretive Criteria:

<0.01 IU/mL Nonprotective Antibody Level

≥0.01 IU/mL Protective Antibody Level

This test was developed and its performance characteristics have been determined by Focus Diagnostics. Performance characteristics refer to the analytical performance of the test.

Haemophilus influenzae Type B Antibody (IgG)

Reference Range:  ≥1.00 mcg/mL post-vaccination (protective level)

Interpretive Criteria:

<0.15 mcg/mL Nonprotective Antibody Level

0.15 - 0.99 mcg/mL Indeterminate for protective antibody

≥1.0  mcg/mL Protective Antibody Level

IgG antibody to polyribosylribitol phosphate (PRP), the capsular polysaccharide of Haemophilus influenzae type b, is measured in micrograms/mL (mcg/mL), based on correlations with a reference Farr radioimmunoprecipitation assay (RIA). The exact level of antibody needed for protection from infection has not been clarified; values ranging from 0.15 mcg/mL to 1.0 mcg/mL have been reported. A four-fold increase in the PRP IgG antibody level between pre-vaccination and post-vaccination sera is considered evidence of effective immunization.

Tetanus Antitoxoid

Reference Range:  ≥0.50 IU/mL (Post-Vaccination)

Interpretive Criteria:

<0.05 IU/mL Nonprotective Antibody Level

0.05 - 0.49 IU/mL Indeterminate for Protective Antibody

≥0.50 IU/mL Protective Antibody Level

Levels greater than or equal to 0.50 IU/mL are generally considered protective, whereas levels less than 0.05 IU/mL indicate a lack of protective antibody. Levels between 0.05 and 0.49 IU/mL are indeterminate for the presence of protective antibody and may indicate a need for further immunization to tetanus toxoid.

This test was developed and its performance characteristics have been determined by Focus Diagnostics. Performance characteristics refer to the analytical performance of the test. 

Streptococcus Pneumoniae IgG Ab (6 Serotypes), MAID

   Serotype 1 (1)              mcg/mL

   Serotype 3 (3)              mcg/mL

   Serotype 14 (14)          mcg/mL

   Serotype 19 (19F)        mcg/mL

   Serotype 23 (23F)        mcg/mL

   Serotype 51 (7F)          mcg/mL

Note: Serotype designations are American nomenclature, with Danish nomenclature in parentheses.

Studies from the 1980’s using radioimmunoassay suggested that vaccine-induced S. pneumoniae type-specific antibody levels of approximately 2.0 mcg/mL were protective against invasive pneumococcal disease. Newer methods (ELISA and multiplexed immunoassay) incorporating an adsorption step to remove cross-reactive antibodies yield results that are comparable to each other, but are lower than those obtained with the original radioimmunoassay. Rigorous studies of protective antibody levels as determined by the newer methods have not been performed. In addition to antibody quantity, protection also depends on antibody avidity and opsonophagocytic activity.

Evaluation of the response to pneumococcal vaccination is best accomplished by comparing pre-vaccination and post-vaccination antibody levels. A 2- to 4-fold increase in type-specific antibodies measured 4-6 weeks after vaccination is expected in immuno-competent adults. The number of serotypes for which a 2- to 4-fold increase is observed varies greatly among individuals; a consensus panel has suggested that individuals older than 5 years should respond to at least approximately 70% of pneumococcal serotypes. Adults >65 years old may exhibit a smaller (<2-fold) increase in type-specific antibody levels.

This test was developed and its performance characteristics have been determined by Focus Diagnostics. Performance characteristics refer to the analytical performance of the test.