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H. influenzae Antibody Haemophilus influenzae B Vaccine Response HIB (Haemophilus influenzae Type B) Vaccine Response
Assessing a patient's immunological (IgG) response to Haemophilus influenzae type B (HIB) vaccine
Assessing immunity against HIB
Aiding in the evaluation of immunodeficiency when the patient is tested pre- and post-vaccination
This assay does not provide diagnostic proof of the presence or absence of immune deficiency. Results must be confirmed by clinical findings and other laboratory tests.
Haemophilus influenzae type B (HIB) is an encapsulated Gram-negative cocco-bacillary bacterium that can cause devastating disease in unvaccinated young children, including meningitis, bacteremia, cellulitis, epiglottitis, pneumonia, and septic arthritis. The outer surface of H influenzae is covered by a polyribosyl-ribitol-phosphate (PRP) polysaccharide that is responsible for both pathogenicity and immunity. There are currently 6 recognized PRP serotypes, referred to as a through f, among which serotype b, prior to the availability of a vaccine, accounted for up to 95% of infections. There are also unencapsulated or nontypable strains.
Prior infection with H influenzae is associated with protective immunity against reinfection. One of the great advances in modern medicine has been the development of an effective vaccine against HIB, which is based on use of an unconjugated, purified PRP antigen. A patient's immunological response to HIB vaccine can be determined by measuring anti-HIB IgG antibody levels using a standardized enzyme immunoassay (EIA). Antibody levels of1 mcg/mL or more at least 3 weeks after vaccination has been correlated with long-term protective immunity.
> or =0.15 mg/L
Reference values apply to all ages.
An anti-Haemophilus influenzae type B (HIB) IgG antibody concentration of 0.15 mcg/L is generally accepted as the minimum level for protection at a given time; however, it does not confer long-term protection. A study from Finland suggested that the optimum protective level is 1.0 mcg/L postimmunization. Furthermore, studies have shown that the response to HIB vaccine is age-related.