Interlaboratory comparison of three multiplexed bead-based immunoassays for measuring serum antibodies to pneumococcal polysaccharides.

Serotype-specific IgG, as quantified by a standardized WHO enzyme-linked immunosorbent assay (ELISA), is a serologic end point used to evaluate pneumococcal polysaccharide-based vaccine immunogenicity. Antibodies to each vaccine polysaccharide in licensed multivalent vaccines are quantified separately; this is laborious and consumes serum. We compared three bead-based immunoassays: a commercial assay (xMAP Pneumo14; Luminex) and two in-house assays (of the Health Protection Agency [HPA] and Centers for Disease Control and Prevention [CDC]), using the WHO-recommended standard reference and reference sera (n = 11) from vaccinated adults. Multiple comparisons of the IgG concentrations for seven conjugate vaccine serotypes were performed by sample (percent error), serotype (equivalency testing), and laboratory (concordance correlation coefficient [CCC]). When comparing concentrations by sample, bead-based immunoassays generally yielded higher antibody concentrations than the ELISA and had higher variability for serotypes 6B, 18C, and 23F. None of the three assays met the current WHO recommendation of 75% of sera falling within 40% of the assigned antibody concentrations for all seven serotypes. When compared by serotype, the CDC and HPA tests were equivalent for five of seven serotypes, whereas the Luminex assay was equivalent for four of seven serotypes. When overall mean IgG concentrations were compared by laboratory, a higher level of agreement (CCC close to 1) was found among bead-based immunoassays than between the assays and WHO assignments. When compared to WHO assignments, the HPA assay outperformed the other assays (r = 0.920; CCC = 0.894; coefficient of accuracy = 0.972). Additional testing with sera from immunogenicity studies should demonstrate the applicability of this methodology for vaccine evaluation.

Evaluation of body mass index, pre-vaccination serum progesterone levels and anti-anthrax protective antigen immunoglobulin G on injection site adverse events following anthrax vaccination in women.

BACKGROUND: In 2002, CDC initiated the Anthrax Vaccination Program (AVP) to provide voluntary pre-exposure anthrax vaccination for individuals at high risk for exposure to Bacillus anthracis spores. The AVP offered an opportunity to investigate hypothesized reasons for a reported gender difference in injection site adverse events (AEs) following anthrax vaccine adsorbed (AVA). OBJECTIVES: To evaluate in women the impact of body mass index (BMI), pre-vaccination serum progesterone levels, and pre-vaccination anti-anthrax protective antigen immunoglobulin G concentrations (anti-PA IgG) on the occurrence of AEs following subcutaneous AVA vaccination. METHODS: Participants' BMI was determined at enrollment. Also, pre-vaccination blood samples were assayed for serum progesterone and anti-PA IgG. Post-vaccination solicited AEs were recorded by participants using a 4-day diary card. RESULTS: Obese group had an elevated risk for arm soreness. Decreased pre-vaccination serum progesterone level was associated with arm swelling. Increased pre-vaccination anti-PA IgG was associated with itching on the arm; and within the obese group, was associated with arm swelling, lump or knot, redness, soreness, and warmth. CONCLUSIONS: In AVA vaccinated women, obesity was associated with arm soreness and decreased pre-vaccination serum progesterone levels were associated with increased rate of arm swelling. Increased pre-vaccination anti-PA IgG may be associated with an increased frequency of itching on the arm, and in obese women, may increase the occurrence of arm swelling, lump or knot, redness, and warmth. Administering AVA according to a woman's menstrual phase may reduce the occurrence of certain injection site reactions.