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An enzyme-linked immunoassay (EIA) is described and evaluated which quantitates human antibodies to serotype specific S. pneumoniae polysaccharide (PnPs) in human sera. Based on the observations previously described by Koskela (1), native PnPs are used as coating antigens and sera are absorbed with a soluble pneumococcal absorbant material containing C-polysaccharide (CPs) to ensure measurement of serotype specific anti-PnPs antibodies. The robustness of this method was evaluated by ten laboratories using the same reagents, protocol, and five human serum samples. Reproducible antibody values were obtained for IgM, IgG, and IgA antibodies to five different PnPs serotypes, 3, 6B, 14, 19F, and 23F. The overall mean percent coefficients of variation in this interlaboratory study for all five serotype specific anti-PnPs determinations with the five coded sera were 30% for IgG, 37% for IgM, and 36% for IgA. This assay can be standardized for quantitation of serotype specific anti-PnPs antibodies, allowing comparison of antibody values in vaccine trials evaluating pneumococcal vaccines. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to identify risk factors for relapse (psychiatric emergency department visits or hospitalization) and lack of follow-up with outpatient psychiatric care in the 12 months after ending services in an urban safety net coordinated specialty care (CSC) program for first episode psychosis (FEP)., Methods: The study population (n = 143) were individuals with FEP who had any CSC care between 2014 and 2021. To identify risk factors for relapse and follow up after exit, multivariable logistic regression was performed using data from electronic health records and linked insurance claims data., Results: Individuals with any emergency department visit or hospitalization 12 months prior to ending CSC (aOR = 4.69, 95 % CI 1.78-12.34) and those who were using cannabis at last CSC contact (aOR = 4.06, 95 % CI 1.56-10.56) had a higher risk of relapse after ending CSC services. Cannabis use at last contact was also associated with lower rates of outpatient psychiatric follow-up (aOR = 0.32, 95 % CI 0.12-0.94), while CSC duration in months had a small positive association with post-CSC psychiatric follow-up. There were no differences in relapse or follow-up by race or ethnicity, primary diagnosis, or medication usage., Conclusions: Prior relapse during CSC predicted relapse in the 12 months after ending CSC services, but not outpatient follow up. Cannabis use predicted both a higher rate of relapse and a lower rate of follow up after ending services. There were no differences by race or ethnicity in our sample, suggesting that once individuals engaged in FEP care there were no evident disparities in the observed outcomes., Competing Interests: Declaration of competing interest The authors have no relevant conflicts of interest to disclose., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Pneumococcal conjugate vaccines are important for the prevention of serious illness and death among infants. Factors associated with pneumococcal conjugate vaccine immunogenicity have not been explored., Methods: Children <24 months of age received 2, 3, or 4 doses of 7-valent pneumococcal conjugate vaccine (PnCRM7) or control vaccine depending on age at enrollment. Serum samples were tested for serotype-specific antibodies by enzyme-linked immunosorbant assay. Multiple linear regression was used to determine predictors of immunogenicity., Results: Among 315 PnCRM7-vaccinated subjects and 295 control subjects enrolled at <7 months of age, geometric mean concentrations (GMCs) of antibodies were significantly higher after dose 3 than after dose 2 for all serotypes except type 4. The proportion of subjects with antibody concentrations > or =5.0 micro g/mL was higher for all serotypes, but the proportion with concentrations > or =0.35 micro g/mL was higher only for types 6B and 23F. Three-dose and 2-dose regimens for those 7-11 and 12-23 months of age, respectively, were highly immunogenic. Increased maternal antibody concentrations were associated with reduced responses to dose 1 and 3 but not to dose 4 of PnCRM7., Conclusions: Maternal antibody is associated with a reduced infant response to PnCRM7 but does not interfere with immune memory. In infants, a third priming dose increases the antibody GMC and the proportion achieving an antibody concentration > or =5.0 micro g/mL but has little impact on the proportion achieving a concentration > or =0.35 micro g/mL.

The capsular polysaccharide of Neisseria meningitidis serogroup W135 is expressed in both O-acetyl-positive (OA+) and O-acetyl-negative (OA-) forms. This study investigates the impact of OA status (OA+ versus OA-) on serological measurements of anti-W135 immunoglobulin G (IgG) antibodies in immunized adults. W135-specific serum antibody assignments were made for 28 postimmunization sera from adults by enzyme-linked immunosorbent assay using the meningococcal standard reference serum CDC1992. The established IgG concentration in micrograms per milliliter ([IgG]microg/ml) for CDC1992 against OA+ antigen (16.2 microg/ml) was used as a reference to assign a concentration of 10.13 microg/ml IgG against OA- antigen by cross-standardization. Overall, the IgG assignments for these sera were higher against OA+ antigen (geometric mean concentration [GMC] = 7.16 microg/ml) than against OA- antigen (GMC = 2.84 microg/ml). However, seven sera showed higher specific [IgG]microg/ml values against the OA+ antigen than against the OA- antigen. These sera were also distinguished by the inability of fluid-phase OA- antigen to compete for antibody binding to OA+ solid-phase antigen. Although there was no overall difference in functional activity measured by complement-mediated serum bactericidal assay (SBA) against OA+ and OA- target bacteria (geometric mean titers of 9,642 and 9,045, respectively), three serum specimens showed a large difference in SBA antibody titers against OA+ versus OA- W135 target bacteria, which may reflect different epitope specificities for these sera. Our data indicate that, for some sera, the agreement in anti-OA+ versus anti-OA- W135 IgG assignments is serum specific and does not reflect the functional (killing) activity in vitro.

Human sera collected from 28 consenting adult volunteers were used to define assay conditions for meningococcal vaccine clinical trial serology. Immunoassay parameters were optimized with these test sera and the standard reference serum, CDC1992. Coating conditions for serogroup Y and W135 polysaccharide antigens were found to influence the predicted serum immunoglobulin G (IgG) antibody concentrations. Sera that displayed IgG antibody binding profiles most unlike that of CDC1992 were influenced the most by coating conditions. Our results suggest that presentation of specific epitopes is influenced by antigen-coating concentrations for serogroup Y and W135 polysaccharides.

Background: Following widespread use of conjugate pneumococcal vaccine, Neisseria meningitidis likely will become the leading cause of bacterial sepsis and meningitis in US children. This report describes the safety and immunogenicity in US children of four consecutive doses of a meningococcal group C vaccine conjugated to CRM197 via reductive amination (MnCC)., Methods: One hundred six healthy 2-month-old infants received MnCC at 2, 4 and 6 months of age in a randomized, controlled double blind study; children in the other treatment arm were given a 7-valent conjugate pneumococcal vaccine. Parents reenrolled 64 of these children at 12 to 15 months to receive a fourth dose of MnCC. Routine childhood vaccines, including DTP, were coadministered. Temperatures and symptoms were recorded for 3 days after each immunization. Serum enzyme-linked immunosorbent assay IgG and bactericidal antibodies were measured prevaccination and before and 1 month after Doses 3 and 4., Results: Moderate to severe local reactions, defined as erythema or induration > or =2.4 cm or pain that interfered with limb movement was reported after 0 to 3.2% of MnCC injections, depending on the reaction and dose. Fever occurred in 23 to 37% of children, but the contribution of MnCC to the febrile reactions is unknown. Geometric mean concentrations of IgG antibody to group C meningococcal polysaccharide were 3.72 microg/ml after Dose 3 and 8.03 microg/ml after the booster. Geometric mean functional serum bactericidal antibody titers after Doses 3 and 4 were 1:463 and 1:2341, respectively. One hundred percent of children had a serum bactericidal antibody titer of > or =1:64 after three doses and > or = 1:128 after the booster., Conclusions: The MnCC vaccine had an acceptable safety profile and generated high titers of bactericidal antibody in immunized US infants and toddlers. It appears to be an attractive candidate vaccine for the prevention of serogroup C meningococcal disease in young children.

A new meningococcal group C-CRM(197) conjugate vaccine (MnCC; Meningitec) has been evaluated in multiple clinical trials in the United States and most recently has been approved for routine administration in the United Kingdom. Meningococcal serogroup C (MnC)-specific immunoglobulin G (IgG) antibodies in pre- and postimmunization sera obtained from healthy U.S. adults, toddlers, and infants were quantitated by enzyme-linked immunosorbent assay (ELISA) and by an antibody-dependent, complement-mediated serum bactericidal assay (SBA). Serogroup-specific IgG antibody (micrograms per milliliter) in adults immunized either with the quadrivalent polysaccharide (A, C, Y, and W-135) vaccine or with MnCC showed a strong correlation (r = 0.848 and 0.934, respectively) by linear regression analysis with SBA. Sera from infants immunized with the MnCC (n = 30) and an age-matched unimmunized control group (n = 15) were also analyzed. Linear regression analysis of serum bactericidal and IgG ELISA data from sera obtained at 2 months of age (preimmunization) showed no correlation; however, a high degree of correlation was observed at time points after two (r = 0.877) and three (r = 0.951) immunizations, where significant rises in anti-MnC polysaccharide antibodies occurred relative to the age-matched control group. Infants previously primed with 3 doses of MnCC were given a booster dose of conjugate vaccine at 12 to 15 months of age. The correlation coefficient of ELISA to SBA for combined pre- and postbooster data was r = 0.836 (n = 48 pairs). In conclusion, increases in serum bactericidal activity in immunized adult, toddler, and infant populations were found to correlate very well with increases in serogroup-specific IgG concentrations, whereas the correlation between these two assays in nonimmunized 2-month-old infants was poor. Characterizing the relationship between these methods is important for understanding the significance of antigen-specific antibody concentrations relative to vaccine performance and protection from disease.

Pneumococcal conjugate vaccines will eventually be licensed after favorable results from phase III efficacy trials. After licensure of a conjugate vaccine for invasive pneumococcal disease in infants, new conjugate vaccines will likely be licensed primarily on the basis of immunogenicity data rather than clinical efficacy. Analytical methods must therefore be developed, evaluated, and validated to compare immunogenicity results accurately within and between laboratories for different vaccines. At present no analytical technique is uniformly accepted and used in vaccine evaluation studies to determine the acceptable level of agreement between a laboratory result and the assigned value for a given serum sample. This multicenter study describes the magnitude of agreement among 12 laboratories quantifying an identical series of 48 pneumococcal serum specimens from 24 individuals (quality-control sera) by a consensus immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) developed for this study. After provisional or trial antibody concentrations were assigned to the quality-control serum samples for this study, four methods for comparison of a series of laboratory-determined values with the assigned concentrations were evaluated. The percent error between assigned values and laboratory-determined concentrations proved to be the most informative of the four methods. We present guidelines that a laboratory may follow to analyze a series of quality-control sera to determine if it can reproduce the assigned antibody concentrations within an acceptable level of tolerance. While this study focused on a pneumococcal IgG ELISA, the methods that we describe are easily generalizable to other immunological assays.

Pneumococcal antibody levels surrounding systemic pneumococcal illness (SPI) were measured in children infected with human immunodeficiency virus (HIV). Archived serum samples were collected from 28 HIV-infected children who had 34 cases of SPI, caused by pneumococcal groups 4, 6, 9, 14, 19, and 23. Serum samples collected within 23 weeks before and 13 weeks after the SPI were assayed by ELISA for antipneumococcal polysaccharide (PnPs) IgG antibody to 6 representative pneumococcal serotypes. There was a wide range (0. 16-30.80 microg/mL) of pre-SPI anti-PnPs antibody levels to the presumed infecting serotypes, with a geometric mean level of 0.83 microg/mL (n=34). Seventy-six percent of the antibody values were <2.0 microg/mL, and 95% were <5.0 microg/mL. Homologous seroresponses (>/=4-fold rise in anti-PnPs antibody) were detected in only 4 (27%) of 15 paired serum samples. Heterologous, noninfecting group seroresponses were detected frequently (72%) in the paired serum samples from these 4 homologous group seroresponders.

Objective: To determine the efficacy, safety and immunogenicity of the heptavalent CRM197 pneumococcal conjugate vaccine against invasive disease caused by vaccine serotypes and to determine the effectiveness of this vaccine against clinical episodes of otitis media., Methods: The Wyeth Lederle Heptavalent CRM197 (PCV) was given to infants at 2, 4, 6 and 12 to 15 months of age in a double blind trial; 37,868 children were randomly assigned 1:1 to receive either the pneumococcal conjugate vaccine or meningococcus type C CRM197 conjugate. The primary study outcome was invasive disease caused by vaccine serotype. Other outcomes included overall impact on invasive disease regardless of serotype, effectiveness against clinical otitis media visits and episodes, impact against frequent and severe otitis media and ventilatory tube placement. In addition the serotype-specific efficacy against otitis media was estimated in an analysis of spontaneously draining ears., Results: In the interim analysis in August, 1998, 17 of the 17 cases of invasive disease caused by vaccine serotype in fully vaccinated children and 5 of 5 of partially vaccinated cases occurred in the control group for a vaccine efficacy of 100%. Blinded case ascertainment was continued until April, 1999. As of that time 40 fully vaccinated cases of invasive disease caused by vaccine serotype had been identified, all but 1 in controls for an efficacy of 97.4% (95% confidence interval, 82.7 to 99.9%), and 52 cases, all but 3 in controls in the intent-to-treat analysis for an efficacy of 93.9% (95% confidence interval, 79.6 to 98.5%). There was no evidence of any increase of disease caused by nonvaccine serotypes. Efficacy for otitis media against visits, episodes, frequent otitis and ventilatory tube placement was 8.9, 7.0, 9.3 and 20.1% with P < 0.04 for all. In the analysis of spontaneously draining ears, serotype-specific effectiveness was 66.7%., Conclusion: This heptavalent pneumococcal conjugate appears to be highly effective in preventing invasive disease in young children and to have a significant impact on otitis media.

Objectives: The objectives of this study were (1) to determine the safety and immunogenicity of heptavalent pneumococcal CRM197 conjugate (PNCRM7) vaccine in infants and (2) to determine the effect of concurrent hepatitis B immunization during the primary series and the effect of concurrent diphtheria and tetanus toxoid and acellular pertussis [DTaP (ACEL-IMUNE)] and conjugate CRM197 Haemophilus influenzae type b [HbOC (HibTITER) immunization at time of the booster dose on the safety and immunogenicity of PNCRM7and these other concurrently administered vaccines., Methods: This was a randomized double-blinded study in 302 healthy infants in the Northern California Kaiser Permanente (NCKP) Health Plan. Infants received either PNCRM7 vaccine or meningococcal group C conjugate vaccine as a control at 2, 4 and 6 months of age and a booster at 12 to 15 months of age. Study design permitted the evaluation of immunology and safety of concurrent administration of routine vaccines. Antibody titers were determined on blood samples drawn before and 1 month after the primary series and the booster dose., Results: After the third dose of PNCRM7 geometric mean concentrations (GMCs) ranged from 1.01 for serotype 9V to 3.72 microg/ml for serotype 14. More than 90% of all subjects had a post-third dose titer of > or =0.15 microg/ml for all serotypes, and the percentage of infants with a post-third dose titer of > or =1.0 microg/ml ranged from 51% for type 9V to 89% for type 14. After the PNCRM7 booster dose, the GMCs of all seven serotypes increased significantly over both post-Dose 3 and pre-Dose 4 antibody levels. In the primary series there were no significant differences in GMCs of pneumococcal antibodies between the subjects given PN-CRM7 alone or concurrently with hepatitis B vaccine. At the toddler dose concurrent administration of PNCRM7 and DTaP and HbOC resulted in a near conventional threshold for statistical significance of a post-Dose 4 GMC for serotype 23F [alone 6.75 mirog/ml vs. concurrent 4.11 microg/ml (P = 0.057)] as well as significantly lower antibody GMCs for H. influenza polyribosylribitol phosphate, diphtheria toxoid, pertussis toxin and filamentous hemagglutinin. For all antigens there were no differences between study groups in defined antibody titers that are considered protective., Conclusion: We conclude that PNCRM7 vaccine was safe and immunogenic. When this vaccine was administered concurrently at the booster dose with DTaP and HbOC vaccines, lower antibody titers were noted for some of the antigens when compared with the antibody response when PNCRM7 was given separately. Because the GMCs of the booster responses were all generally high and all subjects achieved similar percentages above predefined antibody titers, these differences are probably not clinically significant.

Most animal species respond with high antibody levels to polysaccharide antigens after they have been covalently linked to a protein carrier, converting a T-cell independent to a T-cell dependent antigen. This chemical modification has enabled the development of glycoconjugate vaccines for Haemophilus influenzae type b, Neisseria meningitidis, and multivalent Streptococcus pneumoniae. This new generation of vaccines can be well characterized physically and chemically to ensure consistent vaccine manufacture. Such analytical tests provide an alternative to animal models for Quality Control Laboratories; biological models can be difficult and costly to develop and use on a routine basis. If animal tests are used, they need to be refined, defined, and validated for their intended purpose.

Quantitation of antibodies to Haemophilus influenzae type b (Hib) polysaccharide has been an active area of investigation associated with the development of polysaccharide and subsequently polysaccharide-protein conjugate vaccines. These clinical studies indicate that there are several serologic parameters associated with Hib vaccine efficacy in infants. Efficacious vaccines elicit polysaccharide-specific antibodies in infants; they prime the immune system for an anamnestic response; the immune response is long-lived through the period of greatest risk for disease; and the elicited antibodies have functional activity as demonstrated in bactericidal and opsonophagocytic assays or protection in an infant rat challenge model. The immune response to different Hib vaccines varies both quantitatively and qualitatively. With the introduction of routine Hib vaccine immunization, vaccine performance can rely on these serologic parameters. Quantitative serologic assays, the radio-antigen binding and enzyme-linked immunosorbent assays, have been developed and standardized. The quality of the antigen as well as optimization of all assay steps and reagents are key to ensuring specific and reproducible antibody quantitation.

A phagocytosis assay for Streptococcus pneumoniae based on flow cytometry (FACS) with human polymorphonuclear cells and human complement was developed for the study of human vaccination antisera. Human prevaccination sera already contain high levels of C-polysaccharide (C-PS) antibodies, which are not protective in humans but which might give false positive results in a flow-cytometry-based assay. Cultures of S. pneumoniae grown to log phase on three consecutive days, followed by heat inactivation, yielded stable and highly encapsulated strains for serotypes 6A, 6B, 14, 19F, and 23F. As a result, only serotype-specific antibodies were able to facilitate phagocytosis of these strains, whereas no phagocytosis was observed with antibodies against C-PS or pneumococcal surface proteins. No, or weak, phagocytosis was observed with human prevaccination sera, whereas in general, postvaccination antisera facilitated phagocytosis. A highly significant correlation was observed between enzyme-linked immunosorbent assay titers and FACS phagocytosis titers (r = 0.98, P < 0.001) for serotype 23F pneumococci with human vaccination antisera. For all serotypes, interassay variation was below 10%. Major advantages of this assay over the classical killing assay are that (i) limited amounts of sera are required (10 microliter per titration curve), (ii) 600 samples can be processed in one day by one person, and (iii) cells can be fixed and measurement of the samples can be performed up to 1 week later.

Objective: To determine the safety and immunogenicity of heptavalent pneumococcal saccharide vaccine (serotypes 4, 6B, 9V, 14, 18C, 19F, 23F) individually conjugated to CRM197 (PNCRM7), administered at 2, 4, 6, and 12 to 15 months of age., Design: Two hundred twelve healthy 2-month-old infants were equally randomized to receive four consecutive doses of PNCRM7 or an investigational meningococcal group C conjugate vaccine, which served as a control. Concomitantly administered routine vaccines were oral polio vaccine and combined diphtheria toxoid, tetanus toxoid, and whole cell pertussis vaccine/Haemophilus influenzae type b vaccine consisting of capsular oligosaccharides conjugated to CRM197 (DTP/HbOC) at 2, 4, and 6 months, and either measles-mumps-rubella vaccine or HbOC at 12 to 15 months. Active safety surveillance was conducted for 3 days after each dose. Antibody concentrations to each of the 7 pneumococcal serotypes were measured by enzyme-linked immunosorbent assay prevaccination, after doses two and three, prebooster, and postbooster., Results: Significantly fewer children experienced local reactions at the PNCRM7 injection site than at the DTP/HbOC site. There was no increase in the incidence or severity of local reactions at the PNCRM7 site with increasing doses of vaccine. Mild to moderate postvaccination fever was common in both the PNCRM7 and control vaccine groups, however DTP/HbOC was administered concurrently. All 7 vaccine serotypes were immunogenic. The kinetics of the immune responses were serotype-specific. After three doses of PNCRM7, between 92% to 100% of children had >/=0.15 microg/mL of antibody, and 51% to 90% achieved a level of >/=1 microg/mL against specific serotypes. A booster dose of PNCRM7 resulted in a brisk anamnestic response to all 7 vaccine serotypes, demonstrating effective stimulation of T-cell memory by the primary series of vaccinations., Conclusion: Primary immunization followed by a booster dose of PNCRM7 seemed to be acceptably safe and resulted in significant rises in antibody to all 7 serotypes. Implications. Studies to assess vaccine efficacy of PNCRM7 for prevention of systemic disease, nasopharyngeal colonization, and acute otitis media are in progress. If PNCRM7 proves to be protective, there is the potential to prevent up to 85% of invasive pneumococcal disease occurring in US children.

Objective: To compare the safety and immunogenicity of a 5-valent pneumococcal conjugate vaccine to a licensed 23-valent polysaccharide pneumococcal vaccine in HIV-infected and non-HIV-infected children > or = 2 years old., Methods: Thirty HIV-infected and 30 non-HIV-infected children > or = 2 years old were randomized to receive either a 5-valent pneumococcal conjugate vaccine (PCV) or a 23-valent pneumococcal polysaccharide vaccine (PPV) intramuscularly. Children who received PCV initially were given PPV after 6 weeks. Sera were obtained before and at 6 and 12 weeks after the first vaccination to determine IgG pneumococcal antibody titers by enzyme-linked immunosorbent assay to the 5 serotypes represented in the PCV., Results: Both vaccines were well-tolerated with no significant differences in the rates of fever (0 to 14%) or local reactions (0 to 40%) noted between PCV and PPV recipients. Pre-first vaccination geometric mean antibody titers (combined PCV and PPV recipients) to 3 of the 5 pneumococcal types tested were significantly lower in HIV-infected than in non-HIV-infected children (in microgram/ml: type 6B, 0.179 vs. 0.565; type 14, 0.026 vs. 0.060; type 23F, 0.025 vs. 0.119, respectively; P < 0.05). Fewer > or = 4-fold titer rises were observed in HIV vs. non-HIV-infected children whether they received PCV initially (60% vs. 79%, P < 0.05) or PPV (31% vs. 59%, P < 0.05). Also PCV elicited more > or = 4-fold titer rises compared with PPV in HIV-infected (60% vs. 31%, P < 0.05) and non-HIV-infected (79% vs. 59%, P < 0.05) children. No consistent antibody-boosting effect was noted in subjects who received PPV after PCV., Conclusions: We conclude that antibody responses to natural infection, PCV and particularly PPV are poorer in HIV-infected than in non-HIV-infected children. PCV is as safe as and more immunogenic than the currently licensed PPV among HIV-infected and non-HIV-infected children.

An interlaboratory study was conducted to determine whether an enzyme-linked immunosorbent assay (ELISA) with an antigen preparation composed of various-sized fragments of Haemophilus influenzae type b polysaccharide conjugated to human serum albumin could be standardized across laboratories and whether the ELISA-derived results from different laboratories are equivalent to those obtained by the standard radioactive antigen binding assay (RABA) for quantitation of anti-H, influenzae type b polysaccharide antibodies. Twenty coded human serum samples were quantitated by ELISA in 11 laboratories and by RABA in 5 laboratories. The mean RABA-derived values served as the basis for all comparisons. While the overall correspondence of antibody values between the two methods was good, significant differences were found among some of the 11 ELISA data sets and among the mean RABA values. Seven laboratories generated higher ELISA antibody values for low-titered sera. Four laboratories generated antibody concentrations that were not statistically different between the two assay methods. The results therefore indicate that the ELISA can tolerate substantial variations in protocol, such as the use of different plates and different antibody reagents, without affecting the quantitation of serum antibodies. However, attention should be focused on low-titered sera, as some assay conditions may yield spurious results. This ELISA is a serologic assay which can serve as an alternative to the RABA for quantitation of antibodies to H. influenzae type h polysaccharide.

Epidemiological surveillance programs have shown that before the introduction of effective vaccines, Haemophilus influenzae type b (Hib) was the primary pathogen associated with bacterial meningitis in children. Vaccines composed of the bacterium's polysaccharide conjugated onto protein carriers began to be introduced into routine health care practices for infants as early as 1989 in some European countries. Continued introduction in industrialized nations, including the United States in late 1990, has resulted in the rapid decline in the incidence of reported invasive Hib disease. Follow-up surveillance studies show that (a) the decline in the incidence of Hib disease is temporally related to the introduction of effective vaccines, (b) the decline in Hib epiglottitis preceded the decline in meningitis in the United States, (c) the incidence of disease declined in children under the age of 5 years but remained constant in older children and adults, (d) other bacterial pathogens are now the primary causative agents of infant meningitis and epiglottitis even though the incidence of disease caused by these other pathogens has not changed, and (e) the pharyngeal carriage rate of Hib in children has declined without any evidence of an increase in the carriage of non-type b strains or other pathogens. The introduction of effective conjugate vaccines appears to protect at-risk children from invasive Hib disease as well as reduce the opportunities for interpersonal transmission of this bacterium. In addition, Hib conjugate vaccine utilization has benefited society through economic savings.

A human reference serum pool, lot 89-S, has been developed for use in quantitating concentrations of antibody to Streptococcus pneumoniae. Weight-based units have been assigned to antibodies to 11 pneumococcal polysaccharide (PnPs) serotypes (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F) by using enzyme-linked immunosorbent assay methodology and a human standard reference serum, USNRP IS 1644. The experimentally derived assignments for anti-PnPs antibodies of the immunoglobulin G (IgG), IgM, and IgA isotypes in lot 89-S correlate well to the separately determined immunoglobulin assignment. These assignments for this antipneumococcal standard serum were used to quantitate IgG, IgM, and IgA isotype levels and the total immunoglobulin level in pediatric samples from a pneumococcal conjugate vaccine trial. The data indicate that these assignments may be used to assess levels of antibody to PnPs serotypes in human serum.

The safety of the combined oligosaccharide conjugate Haemophilus influenzae (Hib) type b (HbOC) and whole cell diphtheria-tetanus toxoids-pertussis (DTP) vaccine (Tetramune, HbOC-DTP; Lederle) in infancy was evaluated in 6644 recipients of this vaccine and compared with 3914 recipients of separate injections of whole cell DTP and HbOC vaccines when given as a three dose regimen to infants at 2, 4 and 6 months of age in each group. Of the total number of infants in the study, a subset of 1435 were enrolled into the study and then randomly assigned to receive either the Hib-DPT combined vaccine or the separate components. This subset was used to assess local and systemic side effects which were evaluated utilizing telephone interviews 48 to 72 hours after vaccine. The remaining children in the study population were enrolled in a nonrandomized manner. For these children parents were offered the experimental Hib-DPT vaccine and refusers were given HbOC and DTP. Both of these groups of children as well as the randomized subset described above were used to assess rates of episodes of hospitalization, emergency room utilization and sudden infant death syndrome in HbOC-DTP recipients and children who received HbOC and DTP separately. Immunogenicity was evaluated in 123 children by collection of a single serum sample 30 days after the third dose of HbOC-DTP. The observed immunogenicity was comparable to that observed in other recent studies for HbOC and DTP component antigens. The profile of local and systemic side effects observed was virtually identical to that observed after DTP plus HbOC given separately.(ABSTRACT TRUNCATED AT 250 WORDS)

Objective: To study the safety and immunogenicity of a combined diphtheria-tetanus-pertussis (DTP)-Haemophilus influenzae type b (HbOC) vaccine (TETRAMUNE) in infants as young as 2 months of age as compared to separate administration of DTP and HbOC., Methods: Two-month-old infants were randomized to receive three doses 2 months apart of either DTP-HbOC as a single 0.5-mL injection or to receive 0.5 mL of DTP and HbOC concurrently in separate legs. Local and systemic adverse reactions were monitored within 72 hours of each immunization, and immunogenicity of each of the four vaccine components was measured., Results: The incidence of both local and systemic adverse events following the tetravalent vaccine was similar to the incidence following separate vaccine administration. After three doses of vaccine, the response to each of the vaccine components was higher in the combined vaccine when compared to separate administration. In the case of the Haemophilus influenzae type b component, this enhancement was also seen after two doses. The response to the combined vaccine was consistent among the three lots tested as was the enhancement over separate administration., Conclusions: The DTP-HbOC vaccine was safe and immunogenic in young infants and was generally more immunogenic than separate vaccination with DTP and HbOC. The use of such a combined vaccine reduces the number of injections given to young infants by half and is an important step toward improving vaccine delivery.

Objective: To evaluate the immunologic potential of infants 7 to 15 months of age to respond to Haemophilus influenzae type b polysaccharide vaccine following immunization with H influenzae b oligosaccharide-CRM197 conjugate vaccine., Study Design: One hundred seventy-one infants, aged 7 to 15 months, were consecutively and alternatively assigned to one of three immunization protocols. Group 1 (n = 71) received three doses of H influenzae b oligosaccharide-CRM197 conjugate vaccine, group 2 (n = 47) received two doses of H influenzae b oligosaccharide-CRM197 conjugate vaccine followed by one dose of H influenzae type b polysaccharide vaccine, and group 3 received one dose of H influenzae b oligosaccharide-CRM197 conjugate vaccine followed by two doses of H influenzae type b polysaccharide vaccine. Immunizations were given on day 0 and at 2 months and 6 months. Anti-H influenzae type b polysaccharide antibody levels were measured on day 0 and 2, 3, 6, 7, and 12 months after the study began., Results: Haemophilus influenzae type b polysaccharide vaccine given as a second dose stimulated an antibody rise but did so less effectively than H influenzae b oligosaccharide-CRM197 conjugate vaccine. Two doses of H influenzae b oligosaccharide-CRM197 conjugate vaccine were highly immunogenic; geometric means were 31 and 35 micrograms/mL in the 7- to 11-month and 12- to 15-month age groups, respectively. Following two doses of H influenzae b oligosaccharide-CRM197 conjugate vaccine, both immunization protocols resulted in (1) equally high geometric mean antibody levels 1 month after immunization and (2) similar geometric mean antibody levels 6 months after immunization., Conclusions: Haemophilus influenzae b oligosaccharide-CRM197 conjugate vaccine induces antibody levels that would be expected to protect infants from initial invasion and primes the immune system for an anamnestic response. Our data indicate that if a booster immunization is needed, H influenzae type b polysaccharide vaccine could be an alternative to H influenzae b oligosaccharide-CRM197 conjugate vaccine.

The incidence of antigenuria was documented after vaccination of 75 children 15 to 60 months of age with one of three Haemophilus influenzae type b conjugate vaccines, PRP-D (ProHIBiT), PRP-T and HbOC (HibTITER). Unconcentrated and concentrated urine was tested on the first, third, fifth and seventh days after vaccination. Antigenuria occurred on Day 1 in 100% of PRP-D, 43% of PRP-T and 12% of HbOC recipients. The percentages of children excreting antigen on Day 3 were 95, 17 and 8%; on Day 5 they were 36, 4 and 12%; and on Day 7 they were 14, 0 and 18% for PRP-D, PRP-T and HbOC, respectively. The difference in the occurrence of antigenuria resulting from each vaccine was statistically significant on Day 1 and for PRP-D compared with PRP-T or HbOC on Day 3. It is important for clinicians to be aware of the frequency with which antigenuria occurs after these vaccines so that appropriate therapeutic decisions can be made.

An ELISA measuring total Ig antibodies to the capsular polysaccharide of Haemophilus influenzae type b (HbPs) in human sera using an antigen composed of Haemophilus b oligosaccharides conjugated to human serum albumin (HbO-HA) was shown to have an excellent correlation to the radioantigen binding assay (RABA). When 214 sera with different anti-HbPs levels were assayed for total Ig by HbO-HA ELISA and by RABA the correlation coefficient was 0.917 and the paired t test p value was 0.575. Use of competitive ELISA employing soluble HbPs, HbO-HA and human albumin as competitors, showed that the HbO-HA ELISA was specific for antibodies to HbPs. The HbO-HA ELISA yielded reproducible results both within and between laboratories. The HbO-HA ELISA can also be used to determine the isotype of anti-HbPs antibodies by using isotype specific enzyme conjugates. The sum of the IgG, IgA and IgM HbO-HA ELISA results had excellent correlation to the RABA results (correlation coefficient = 0.976). Thus, the HbO-HA ELISA can be substituted for the classical RABA and also be utilized for quantitating the isotype of the anti-HbPs antibodies.

A total of 268 infants aged 15 to 23 months received one dose of a vaccine composed of Haemophilus influenzae type b oligosaccharides covalently linked to the nontoxic diphtheria toxin variant CRM197 (HbOC; HibTITER). Side effects associated with vaccination were infrequent, transient, and mild. One month after a single vaccination, the anti-H influenzae type b capsular polysaccharide antibody concentration rose from a geometric mean prevaccination level of 0.20 microgram/mL to 13.77 micrograms/mL. Of these infants, 99% had a postvaccination level greater than or equal to 1.00 microgram/mL, a level associated with long-term protection. The immune response was long-lived: all of the children who were monitored 17 to 27 months after vaccination had concentrations greater than or equal to 1.00 microgram/mL. The anti-H influenzae type b capsular polysaccharide antibody generated was predominantly of the IgG isotype and IgG1 subclass. The immune sera had bactericidal activity in vitro and conferred passive protection in the infant rat meningitis model.

A defect in antibody response to immunization with Haemophilus influenzae type b (Hib) capsular polysaccharide vaccine has been reported in children with recurrent infections and normal immunoglobin levels. We identified 15 children, aged 2 to 6 years, with this defect, and we evaluated their response to immunization with an Hib capsular oligosaccharide diphtheria CRM197 protein-conjugate vaccine (HbOC). The children received a series of three vaccines: HbOC at 0 and 8 weeks, and the Hib polysaccharide vaccine at 16 weeks. Levels of antibody to the Hib capsular polysaccharide (polyribosyl ribitol phosphate, PRP) and to diphtheria toxoid were obtained before and 4 weeks after each vaccination. The geometric mean serum anti-PRP concentration was 0.17 microgram/ml before immunization and 29.3 micrograms/ml after the second HbOC immunization (week 12). All 15 children had postvaccination anti-PRP antibody levels greater than 1.0 microgram/ml after receiving the second HbOC (week 12). In addition, booster responses were observed after the second Hib conjugate in 13 of the patients and after the Hib polysaccharide in four of the patients. All patients with low preimmunization diphtheria titers had a response to the diphtheria toxoid. These results suggest that conjugation of Hib polysaccharide with diphtheria CRM197 overcomes the defective antibody response to Hib oligosaccharide in children who are initially observed with recurrent infections and inability to respond to the Hib polysaccharide vaccine.