A Phase 3, Single-arm Trial to Evaluate the Safety and Immunogenicity of a 20-Valent Pneumococcal Conjugate Vaccine in Healthy Children 15 Months Through <18 Years of Age.

BACKGROUND: A 20-valent pneumococcal conjugate vaccine (PCV20), containing 13-valent PCV (PCV13) components and 7 additional polysaccharide conjugates, was developed to extend protection for pneumococcal disease. This phase 3 study assessed the safety and immunogenicity of PCV20 in children. METHODS: In this single-arm study, children (≥15 months-<18 years of age) received 1 dose of PCV20. Children <5 years of age had ≥3 prior doses of PCV13; children ≥5 years were recruited regardless of previous PCV receipt. Serotype-specific IgG concentrations and opsonophagocytic activity (OPA) titers were measured before and 1 month after PCV20. Local reactions and systemic events, adverse events (AEs), serious AEs, and newly diagnosed chronic medical conditions were collected. RESULTS: Of 839 enrolled participants, 831 (>99%) were vaccinated, and 819 (>97%) completed all study visits. Local reactions and systemic events were mostly mild to moderate in severity. No serious AEs were considered PCV20-related. IgG geometric mean fold rises (GMFRs) from before to 1 month after PCV20 ranged from 27.9-1847.7 (7 additional serotypes) and 2.9-44.9 (PCV13 serotypes) in children <5 years of age, and 10.5-187.7 (7 additional serotypes) and 4.3-127.9 (PCV13 serotypes) in children ≥5 years old. OPA GMFRs from before to 1 month after PCV20 ranged from 12.4-983.6 to 2.8-52.9 in children <5 years of age and from 11.5-499.0 to 5.3-147.9 in children ≥5 years of age. CONCLUSIONS: Among children ≥15 months through <18 years of age, PCV20 was well tolerated and induced robust responses to all 20 serotypes, supporting the use of PCV20 in children.

A Phase Three Study of the Safety and Immunogenicity of a Four-dose Series of 20-Valent Pneumococcal Conjugate Vaccine in Healthy Infants.

BACKGROUND: The 20-valent pneumococcal conjugate vaccine (PCV20) was developed to extend pneumococcal disease protection beyond 13-valent PCV (PCV13). METHODS: This phase 3, double-blind study conducted in the United States/Puerto Rico evaluated PCV20 safety and immunogenicity. Healthy infants were randomized to receive a 4-dose series of PCV20 or PCV13 at 2, 4, 6 and 12-15 months old. Objectives included demonstrating noninferiority (NI) of PCV20 to PCV13 immunoglobulin G (IgG) geometric mean concentrations after doses 3 and 4 and percentages of participants with predefined IgG concentrations after dose 3, with 7 additional PCV20 serotypes compared with the lowest result among vaccine serotypes in the PCV13 group. Safety assessments included local reactions, systemic events, adverse events, serious adverse events and newly diagnosed chronic medical conditions. RESULTS: Overall, 1991 participants were vaccinated (PCV20, n = 1001; PCV13, n = 990). For IgG geometric mean concentrations 1 month after both doses 3 and 4, all 20 serotypes met NI criteria (geometric mean ratio lower 2-sided 95% confidence interval > 0.5). For percentages of participants with predefined IgG concentrations after dose 3, NI (percentage differences lower 2-sided 95% confidence interval > -10%) was met for 8/13 matched serotypes and 6/7 additional serotypes; 4 serotypes missed the statistical NI criterion by small margins. PCV20 also elicited functional and boosting responses to all 20 serotypes. The safety profile of PCV20 was similar to PCV13. CONCLUSION: A 4-dose series of PVC20 was well tolerated and elicited robust serotype-specific immune responses expected to help protect infants and young children against pneumococcal disease due to the 20 vaccine serotypes. Clinical trial registration: NCT04382326.

Safety and Immunogenicity of a 20-valent Pneumococcal Conjugate Vaccine in Healthy Infants in the United States.

BACKGROUND: The development and widespread use of pneumococcal conjugate vaccines (PCVs) substantially reduced the global burden of pneumococcal disease. Expanding the serotypes covered by PCVs may further reduce disease burden. A 20-valent PCV (PCV20) has been developed to add coverage for 7 additional serotypes (8, 10A, 11A, 12F, 15B, 22F and 33F) to those in the existing 13-valent PCV (PCV13). This phase 2 study evaluated the safety, tolerability and immunogenicity of PCV20 in healthy US infants. METHODS: In this randomized, active-controlled, double-blind study, 460 infants were randomized 1:1 to receive a 4-dose series of either PCV20 or PCV13 at 2, 4, 6 and 12 months of age. Solicited local reactions and systemic events, adverse events (AEs) and serious AEs were recorded. Immunogenicity was assessed by measuring serotype-specific IgG concentrations and opsonophagocytic activity titers at 1 month after Dose 3, before Dose 4 and 1 month after Dose 4. RESULTS: Of 460 infants, 82.8% completed the 1-month visit after Dose 4. Local reactions and systemic events were mostly mild to moderate in severity and similar between the PCV20 and PCV13 groups. Treatment-related AEs were uncommon, with no related serious AEs or deaths reported. IgG and opsonophagocytic activity responses elicited by PCV20 were robust and demonstrated a booster response after Dose 4. CONCLUSIONS: Administration of PCV20 in US infants was well tolerated, with a safety profile similar to PCV13, and induced robust serotype-specific immune responses. These findings support continued development of PCV20 in the pediatric population.

Carrier-Induced Hyporesponsiveness to Pneumococcal Conjugate Vaccines: Unraveling the Influence of Serotypes, Timing, and Previous Vaccine Dose.

BACKGROUND: Pneumococcal conjugate vaccines (PCVs) elicit lower immune response against serotypes carried before or at the time of vaccination (hyporesponsiveness) in infants. The limited studies conducted to date did not permit comprehensive insights regarding this phenomenon. This study, the largest ever conducted with both carriage and serologic endpoints, attempted to add insight on serotype-specific hyporesponsiveness in relation to the number of PCV doses administered before carriage acquisition. METHODS: In a double-blind randomized clinical trial (n = 1754 infants), 7-valent or 13-valent PCV was administered at ages 2, 4, 6, and 12 months. New acquisition was defined based on nasopharyngeal swabs at ages 2, 4, 6, 7, and 12 months. Serotype-specific immunoglobulin G levels were obtained 1 month after the infant series and 1 month after the toddler dose. RESULTS: A lower immune response after the infant series and the toddler dose was consistently observed for carriers of serotypes 6A, 6B, 18C, and 19F at predefined time points, with a similar trend observed in carriers of serotype 23F. In contrast, carriage of serotypes 9V, 14, and 19A did not generally affect immune responses. For some but not all serotypes, hyporesponsiveness was decreased with an increased number of vaccine doses received before acquisition. A complex interrelationship between carriage and immune response was observed between cross-reacting serotypes. CONCLUSIONS: Carrier-induced hyporesponsiveness to PCVs is common, differs among serotypes, and depends on timing of carriage acquisition and prior number of administered PCV doses. CLINICAL TRIALS REGISTRATION: NCT00508742.

Effectiveness of 13-valent pneumococcal conjugate vaccination for protection against acute otitis media caused by Streptococcus pneumoniae in healthy young children: a prospective observational study.

BACKGROUND: With wide use of the seven-valent pneumococcal conjugate vaccine (PCV7) for protection against acute otitis media caused by Streptococcus pneumoniae serotypes included in the vaccine, efficacy testing for the 13-valent vaccine (PCV13) was not feasible. We aimed to assess the effectiveness of PCV13 in preventing acute otitis media caused by the six serotypes in PCV13 that were not in PCV7. METHODS: We did a longitudinal observational study in healthy children seen as outpatients in a private paediatric practice in Rochester, NY, USA. Children aged up to 30 months who had received the full primary series of PCV13 with other recommended vaccines were eligible to participate and were followed up to age 30-36 months to identify episodes of acute otitis media, during which we collected middle-ear fluid (MEF) by tympanocentesis. We assessed MEF for the serotypes common to PCV7 and PCV13 (4, 6B, 9V, 14, 18C, 19F, and 23F) and the six additional serotypes specific to PCV13 (1, 3, 5, 6A, 7F, and 19A). As controls, we included children enrolled in a longitudinal study in the study centre from Oct 1, 2007, to Sept 30, 2009, who had been vaccinated with PCV7, had MEF prospectively collected at the onset of acute otitis media, and been followed up until age 30 months. The primary outcome was the effectiveness of PCV13 to prevent acute otitis media caused by pneumococci expressing the six capsular serotypes not included in PCV7 (1, 3, 5, 6A, 7F, and 19A). This study is registered with ClinicalTrials.gov, number NCT01199016. FINDINGS: From Sept 28, 2010, to Sept 30, 2013, we enrolled 239 children (123 [51%] boys and 116 [49%] girls; median age 6·3 months [IQR 6·1-8·6]) in the PCV13 cohort, and 162 completed the study. Of 348 children (184 [53%] boys and 164 [47%] girls; 6·5 months [6·1-9·1]) included in the PCV7 cohort, 248 completed follow-up. 223 MEF samples were obtained at onset of acute otitis media from 90 children in the PCV13 cohort. 53 (24%) of 223 samples were culture positive for S pneumoniae, compared with 89 (31%) of 284 samples in the PCV7 cohort (p=0·06). Four (8%) of 53 samples in the PCV13 cohort contained pneumococci expressing one of the additional PCV13 capsular serotypes, compared with 46 (52%) of 89 samples in the PCV7 cohort, giving a relative reduction of 86% (95% CI 61-94, p=0·0010). The greatest reduction in MEF samples was in serotype 19A (two [4%] in the PCV13 cohort vs 46 [52%] in the PCV7 cohort; relative reduction 91% [58-97, p=0·0010]). INTERPRETATION: PCV13 prevents acute otitis media caused by S pneumoniae expressing serotypes included in the vaccine. FUNDING: Pfizer.

Late onset of injection site reactions after vaccination with the 13-valent pneumococcal conjugate vaccine in adult study populations.

Injection site reactions (ISRs; redness, swelling and pain) commonly occur within 1-2 days after vaccination. After administration of toxoid vaccines including diphtheria toxoid, a later onset of ISRs has also been observed. As the serotype capsular polysaccharides in the 13-valent pneumococcal conjugate vaccine (PCV13) are conjugated to cross-reactive material 197 (CRM197), a nontoxic variant of diphtheria toxin, the onset of ISRs over 14 days was explored in 8 adult studies with 19 cohorts. Subjects received PCV13 with aluminum phosphate (AlPO4, n = 5667) or without AlPO4 (n = 304); 1097 subjects received 23-valent pneumococcal polysaccharide vaccine (PPSV23). Late ISRs with onset between days 6-14 were observed in 8/8 cohorts aged ≥65 years after PCV13 with AlPO4 (incidence across cohorts for redness, 2.3%-19.6%; swelling, 0.9%-10.8%; pain, 1.6%-10.0%) and in 1/1 cohort after PCV13 without AlPO4 (redness 10.5%; swelling 7.5%; pain 12.3%); and in 2/4 cohorts aged 50 to 64 years after PCV13 (redness 3.1%-4.8%; swelling 1.0%-3.2%; pain 3.7%-5%). Late ISRs were not generally observed in 1/1 cohort aged 18 to 49 years after PCV13; in 2/2 cohorts aged ≥53 years after PCV13 revaccination; and in 3/3 cohorts aged ≥60 years who received PPSV23, which does not contain CRM197. Post hoc analysis demonstrated numerically higher pneumococcal immune responses in subgroups with late ISRs versus those without. In conclusion, causality of late ISRs is likely multifactorial, with age and the PCV13 carrier protein CRM197 potentially associated. AlPO4, a vaccine adjuvant, did not appear causally related. Observations do not affect the favorable risk-benefit profile of PCV13.

Serotype-specific immune responses to pneumococcal conjugate vaccine among children are significantly correlated by individual: Analysis of randomized controlled trial data.

BACKGROUND: The magnitude of an individual's serotype-specific immunoglobulin G (IgG) response to a pneumococcal conjugate vaccine (PCV) has been associated with the vaccine's protective efficacy against carriage of pneumococci of that serotype, though the relationship with other serotypes needs to be understood. METHODS: Using immunogenicity data collected during a trial comparing the 7-valent (PCV7) and 13-valent (PCV13) vaccines, we measured associations between serotype-specific IgG levels, and used multiple regressions to identify demographic predictors of response. RESULTS: Vaccine-induced IgG levels were moderately positively correlated with one another, with pairwise correlation coefficients of 0.40-0.70. Principal component analysis of vaccine-serotype responses yielded one principal component indicating general immune responsiveness, and a second principal component mainly describing responses to serotype 14, which was the least correlated with the other responses. Overall, demographic variables explained only 17.0 and 20.4% of the geometric mean PCV7 and PCV13 responses, respectively. In both groups, older age at the first vaccine dose and shorter time from vaccination to antibody measurement were independently associated with stronger geometric mean responses. DISCUSSION: Improved understanding of the nature and causes of variation in immune response may aid in optimizing vaccination schedules and identifying robust correlates of protection.

PCV13-vaccinated children still carrying PCV13 additional serotypes show similar carriage density to a control group of PCV7-vaccinated children.

BACKGROUND: In addition to reducing vaccine-type nasopharyngeal carriage rates, pneumococcal conjugate vaccines (PCVs) may decrease carriage density in vaccinated individuals still carrying vaccine serotypes. However, reduction of carriage density has not been systematically studied. This study compared the effect of PCV13 versus PCV7 on carriage density of the serotypes in PCV13 that are not included in PCV7. METHODS: This randomized, double-blind study was conducted in southern Israel and included Jewish and Bedouin subjects. Per protocol, 881 and 873 infants received PCV13 and PCV7, respectively, at ages 2, 4, 6, and 12months. Nasopharyngeal cultures at ages 7, 12, 13, 18, and 24months were plated using the 4-quadrant semiquantitative method and graded 0 (negative) to 4 (growth in all plate quadrants). In this post hoc analysis, the least squares means of cumulative colonization densities per serotype and serotype combination of the total population and each ethnic subpopulation in each vaccine group were calculated, and differences between vaccine groups derived from a linear model. RESULTS: PCV13-vaccinated children still carrying the 6 additional PCV13 serotypes unique to PCV13 showed no significant differences in carriage density compared with the PCV7-vaccinated control group. No differences in carriage density were shown between Jewish and Bedouin subpopulations despite higher carriage rates among Bedouin subjects. CONCLUSIONS: Although PCV13 vaccination reduces vaccine-type carriage compared with PCV7 vaccination by reducing nasopharyngeal acquisition of the additional PCV13 serotypes as previously reported, the current study lacks evidence of a decrease in carriage density of these serotypes when acquired in vaccinated children. Despite the lack of effect on carriage density observed, surveillance data suggest a dramatic decrease in disease rates after PCV implementation. Thus, the current analysis suggests that PCV's impact on carriage density has minimal or no impact on vaccine success. (www.ClinicalTrials.gov: NCT00508742).

Modeling pneumococcal nasopharyngeal acquisition as a function of anticapsular serum antibody concentrations after pneumococcal conjugate vaccine administration.

BACKGROUND: A prior 7- and 13-valent pneumococcal conjugate vaccine (PCV7 and PCV13) study provided sufficient data (N=1754; Jewish, n=1154; Bedouin, n=595; other, n=5) to investigate the association between nasopharyngeal (NP) acquisition of common PCV7 serotypes and cross-reacting 6A (PCV7+6A) and IgG concentrations. METHODS: Using a logistic regression model, serotype specific association between postinfant series IgG concentration (age 7months) and new NP acquisition between ages 7 and 24months was assessed and adjusted for ethnicity. From a subset of subjects with new NP acquisition (n=9-152 across serotypes studied), new acquisition percentiles and associated IgG concentrations were calculated. RESULTS: For the serotypes studied, new NP acquisition rates decreased as IgG concentrations increased. Ethnicity did not influence these associations despite differences in carriage rates. From the subset with new acquisitions, 50% of the events occurred at IgG concentrations >0.61-5.58µg/mL; and 10% of the acquisitions occurred at IgG concentrations >2.48-17.69µg/mL. CONCLUSION: Remarkably high IgG concentrations are required to reduce NP acquisition. These IgG concentrations differ between serotypes. Ethnicity did not influence the association between high IgG concentrations and prevention of carriage despite differences in carriage rates. Since carriage determines transmission, these results may have important implications for herd protection. TRIAL REGISTRATION: ClinicalTrials.gov number, NCT00508742; http://clinicaltrials.gov/ct2/show/NCT00508742.

Multicenter surveillance of Streptococcus pneumoniae isolates from middle ear and mastoid cultures in the 13-valent pneumococcal conjugate vaccine era.

BACKGROUND: Streptococcus pneumoniae is a common cause of otitis media (OM) in children; mastoiditis remains an important complication of OM. Limited data are available on the impact of the 13-valent pneumococcal conjugate vaccine (PCV13) on pneumococcal otitis. METHODS: Investigators from 8 children's hospitals in the United States prospectively collected pneumococcal isolates from middle ear or mastoid cultures from children from 2011 to 2013. Serotype and antibiotic susceptibilities were determined and PCV13 doses for children documented. RESULTS: Over the 3-year period, the proportion of isolates included in PCV13 (plus a related serotype) decreased significantly (P = .0006) among the middle ear/mastoid isolates (2011, 50% [74/149]; 2012, 40.5% [47/116]; 2013, 29% [34/118]). The number of serotype 19A isolates in 2013 (n = 12, 10.2% of total) decreased 76% compared with the number of 19A isolates in 2011 (n = 50, 33.6% of total). Of the children from whom serotype 19A was isolated (n = 93), 55% had previously received <3 doses of PCV13. The most common non-PCV13 serotypes for the combined years were 35B (n = 37), 21 (n = 20), 23B (n = 20), 15B (n = 18), 11 (n = 17), 23A (n = 14), 15A (n = 14), and 15C (n = 14). The proportion of isolates with a penicillin minimal inhibitory concentration >2 µg/mL decreased significantly over the 3 years (2011, 22% [35/154]; 2012, 20% [24/118]; 2013, 10% [12/120]; P < .02). CONCLUSIONS: The number of pneumococcal isolates and the percentage of isolates with high-level penicillin resistance from cultures taken from children with OM or mastoiditis for clinical indications have decreased following PCV13 use, largely related to decreases in serotype 19A isolates.

Efficacy of 13-valent pneumococcal conjugate vaccine (PCV13) versus that of 7-valent PCV (PCV7) against nasopharyngeal colonization of antibiotic-nonsusceptible Streptococcus pneumoniae.

BACKGROUND: Pediatric respiratory infections caused by antibiotic-nonsusceptible Streptococcus pneumoniae (ANSP) continue to present an important challenge, even after introduction of 7-valent pneumococcal conjugate vaccine (PCV7). This randomized double-blind trial assessed the potential additional impact of PCV13 over PCV7 on reducing ANSP carriage. METHODS: Healthy infants were randomly assigned to receive PCV13 (n = 932) or PCV7 (n = 934) at ages 2, 4, 6, or 12 months. Eight nasopharyngeal specimens were collected by swabbing between ages 2 and 24 months. S. pneumoniae isolates were serotyped and tested for antimicrobial susceptibility by the disk-diffusion method and the Etest. Nasopharyngeal acquisition and prevalence of ANSP during ages 7-24 months were compared between the 2 vaccine groups. RESULTS: In general, new acquisition of pneumococci nonsusceptible to penicillin, erythromycin, clindamycin, penicillin plus erythromycin, and multiple drugs (≥3 antibiotics) was significantly lower in the PCV13 group compared with the PCV7 group; the main serotypes contributing to this significant decrease were serotype 19F, present in PCV13 and PCV7, and serotypes 6A and 19A, present in PCV13 only. CONCLUSIONS: PCV13 has a significant added benefit over PCV7 in reducing carriage of ANSP. Because carriage determines transmission, these results suggest that PCV13 will provide protection against ANSP disease that exceeds protection provided by PCV7. CLINICAL TRIALS REGISTRATION: NCT00508742.

Post hoc analysis of a randomized double-blind trial of the correlation of functional and binding antibody responses elicited by 13-valent and 7-valent pneumococcal conjugate vaccines and association with nasopharyngeal colonization.

In a randomized double-blind trial in healthy Israeli infants in Israel who received the 13-valent or 7-valent pneumococcal conjugate vaccine (PCV13 or PCV7, respectively) at 2, 4, 6, and 12 months, PCV13 significantly reduced nasopharyngeal (NP) colonization of serotypes 1, 6A, 7F, 19A, cross-reacting 6C, and the common PCV7 serotype 19F, from ages 7 to 24 months. No differences were observed between the vaccine groups for serotype 3 or for the remaining common PCV7 serotypes. For serotype 5, too few events were observed to draw an inference. Generally consistent with these findings, PCV13 elicited significantly higher enzyme-linked immunosorbent assay (ELISA) IgG-binding antibody responses than did PCV7 for the additional PCV13 serotypes 1, 3, 5, 6A, 7F, 19A, and for the common serotype 19F, with similar or lower responses for the remaining common serotypes. To further assess immunogenicity and colonization, we conducted a post hoc analysis of PCV13 functional antibody responses measured by opsonophagocytic activity (OPA) assays in a randomly selected subset of subjects. The pattern of functional antibody OPA responses elicited by PCV13 relative to PCV7 was similar to that of the ELISA anticapsular IgG-binding antibody responses described above. In addition, the OPA responses generally correlated positively with IgG responses for all 13 serotypes among the PCV13 recipients and for all 7 common serotypes and the additional serotype 6A but not for 19A or the other serotypes unique to PCV13 among the PCV7 recipients. This post hoc analysis supports an association between serum OPA functional and IgG-binding antibody levels, allowing for a transfer of inferred associations between IgG responses and NP colonization to OPA responses.

Sequential administration of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine in pneumococcal vaccine-naïve adults 60-64 years of age.

BACKGROUND: Unlike free pneumococcal polysaccharide vaccines (PPSVs), pneumococcal conjugate vaccines (PCVs) induce a T-cell-dependent immune response. The study assessed potential influence of initial 13-valent PCV (PCV13) or 23-valent PPSV (PPSV23) on subsequent vaccine administrations. METHODS: We conducted a randomized, modified double-blind study in 720 pneumococcal vaccine-naïve adults 60-64 years of age. Subjects received either PCV13 at year 0 and PCV13 at year 1; PCV13 at year 0 and PPSV23 at year 1; or PPSV23 at year 0 and PCV13 at year 1. Antipneumococcal opsonophagocytic activity (OPA) titers were measured before and 1 month after each vaccination. RESULTS: OPA titers following PPSV23 given 1 year after PCV13 (PCV13/PPSV23) (a) were noninferior for the 12 common serotypes and significantly higher for 6 of 12 common serotypes than those following only an initial PPSV23; and (b) were significantly higher for 11 of 12 common serotypes compared with PPSV23 followed by PCV13 (PPSV23/PCV13). In addition, PPSV23 followed 1 year later by PCV13 (PPSV23/PCV13) elicited significantly lower OPA titers than after only an initial dose of PCV13 for all 13 serotypes. Responses after a second vaccination with either PCV13 (PCV13/PCV13) or PPSV23 (PCV13/PPSV23) were noninferior for 9 of 13 and 8 of 12 common serotypes compared with the initial PCV13 dose. CONCLUSION: In pneumococcal vaccine-naïve adults 60-64 years of age, an initial PCV13 augmented the antipneumococcal response to subsequent administration of PPSV23 for many of the serotypes in common to both vaccines. In contrast, an initial PPSV23 resulted in a diminished response to subsequent administration of PCV13 for all serotypes. With a relatively short 1-year interval between doses, responses after a second vaccination with PCV13 (PCV13/PCV13) or PPSV23 (PCV13/PPSV23) were noninferior for a majority of serotypes compared with the initial PCV13 dose, probably reflecting the need for a longer interval between vaccine administrations. ClinicalTrials.gov Identifier: NCT00574548.

13-Valent pneumococcal conjugate vaccine (PCV13) in children partially immunized with 7-valent pneumococcal conjugate vaccine (PCV7): a phase 3, open-label trial.

BACKGROUND: As 13-valent pneumococcal conjugate vaccine (PCV13) is introduced, children who began vaccination with 7-valent pneumococcal conjugate vaccine (PCV7) may complete their vaccination with PCV13. This open-label phase 3 study evaluated immunogenicity and safety of PCV13 in Swedish infants and toddlers previously given 1 or 2 doses of PCV7 during infancy. METHODS: Healthy infants previously given PCV7 at ages 3 months (group 1; n=118) or 3 and 5 months (group 2; n=116) received PCV13 at ages 5 (group 1) and 12 months (both groups). IgG responses were assessed 1 month after each PCV13 dose and before the 12-month dose. Local reactions and systemic events were collected for 7 days postvaccination. Other adverse events were also collected. RESULTS: Post-5-month dose, IgG geometric mean concentrations (GMCs) in group 1 were 1.56-4.70 µg/ml for most PCV7 serotypes except 6B (0.40 µg/ml) and 23F (0.57 µg/ml) and 0.72-1.88 µg/ml for most of the 6 additional serotypes, except 6A (0.28 µg/ml). Post-12-month dose, IgG GMCs for the PCV7 serotypes were 2.93-9.63 µg/ml (group 1) and 3.33-9.30 µg/ml (group 2); and for the 6 additional serotypes, 1.85-14.65 µg/ml (group 1) and 1.34-13.16 µg/ml (group 2). GMCs increased by >4-fold in both groups from pre- to post-12-month dose. Proportions of subjects in group 1 with pneumococcal serotype-specific IgG concentrations ≥0.35 µg/ml (WHO-designated postprimary reference antibody level) post-5-month dose were 92.2-99.1% for most PCV7 serotypes except 6B (53.0%) and 23F (62.6%) and 80.9-100.0% for most of the 6 additional serotypes except 6A (36.8%). Local reactions and fever were mostly mild or moderate. CONCLUSIONS: PCV13 was immunogenic and safe in infants and toddlers previously partially immunized with PCV7. Even a single dose in an infant or toddler induces an immune response to the 6 additional serotypes.

Immunogenicity and safety of MMRV and PCV-7 administered concomitantly in healthy children.

OBJECTIVE: We assessed the immunogenicity and safety of a combination measles, mump, rubella, and varicella vaccine (MMRV) (ProQuad [Merck & Co, Inc, West Point, PA]) administered to healthy children concomitantly with a pneumococcal 7-valent conjugate vaccine (PCV-7) (Prevnar [Pfizer, Philadelphia, PA]). PATIENTS AND METHODS: Healthy 12- to 15-month-old children who lacked vaccination and clinical histories for measles, mumps, rubella, varicella, and zoster but had written documentation of receipt of a 3-dose primary series of PCV-7 were randomly assigned in a 2:1:1 ratio to receive either the MMRV and PCV-7 (group 1), PCV-7 followed 6 weeks later by MMRV (group 2), or MMRV followed 6 weeks later by PCV-7 (group 3). The primary safety analysis was 56 days (28 days after each visit). Immunogenicity was evaluated 6 weeks after each vaccination. RESULTS: A total of 1027 children were enrolled (group 1: 510; group 2: 258; group 3: 259). For all 3 groups, the antibody response rate was ≥96.8% for measles, mumps, and rubella, ≥88.0% for varicella-zoster virus, and ≥98.3% for all of the 7 Streptococcus pneumoniae serotypes. The immune responses to all antigens present in MMRV and PCV-7 were similar whether administered concomitantly or sequentially. The incidence of local and systemic adverse experiences (AEs) was comparable between group 1 and groups 2 and 3 combined. No vaccine-related serious AEs were reported. CONCLUSIONS: Concomitant administration of the MMRV and PCV-7 is highly immunogenic and generally well tolerated. Similar immune responses between the groups support concomitant administration of the MMRV and PCV-7 to healthy children 12 to 15 months of age.

Hyperfibrinogenemia and functional outcome from acute ischemic stroke.

BACKGROUND AND PURPOSE: Epidemiological studies have found strong correlations between elevated plasma fibrinogen levels and both ischemic stroke incidence and stroke mortality. Little is known about the influence of fibrinogen levels on functional stroke outcome. METHODS: Placebo data from the Stroke Treatment with Ancrod Trial (STAT) and European Stroke Treatment with Ancrod Trial (ESTAT) were analyzed. Fibrinogen levels were determined within 3 hours (STAT) or 6 hours (ESTAT) of stroke onset and at preset intervals throughout 5 days of intravenous infusions. Barthel Index scores at 90 days quantified functional outcomes. The association between initial fibrinogen levels and functional outcomes was evaluated using a multiple logistic regression analysis. RESULTS: Fibrinogen levels increased gradually over the first 24 hours from a pretreatment median value of 340 mg/dL to a 24-hour median value of 376 mg/dL. In a univariate analysis, the proportion of patients with good functional outcome decreased with increasing quartiles of initial fibrinogen levels in both STAT (36.0% to 26.2%) and ESTAT (53.8% to 24.8%). In a multifactorial analysis, the same trend was observed. Patients with initial fibrinogen levels <450 mg/dL had better outcomes in both studies; the difference (42.0% versus 21.6%) was significant in ESTAT (P=0.0006), even when corrected for age and initial stroke severity. CONCLUSIONS: The independent association of higher initial fibrinogen levels with poor outcome needs to be verified using a larger acute stroke dataset. Even in the present small populations, the apparent association of these 2 variables suggests that treatments designed to reduce fibrinogen levels could potentially be important in treating acute ischemic stroke.

Ancrod for acute ischemic stroke: a new dosing regimen derived from analysis of prior ancrod stroke studies.

BACKGROUND: Ancrod, a fibrinogen-reducing agent, has been evaluated as treatment beginning within 3 or 6 hours of onset of acute ischemic stroke with inconsistent results. The data sets from these studies provide an opportunity to determine whether ancrod-related variables are associated with efficacy and safety. OBJECTIVE: This post hoc analysis of data from the Stroke Treatment with Ancrod Trial (STAT) analyzed ancrod-related variables as potential determinants of efficacy or safety. The resulting hypotheses were then tested in the European STAT (ESTAT) database. METHODS: The relationships between ancrod-related variables and the outcomes of efficacy and symptomatic intracranial hemorrhage (ICH) were analyzed using a 3-stage multivariate process. RESULTS: Good clinical outcome at 3 months based on the Barthel Index occurred almost twice as often in rapid defibrinogenators (>or=30 mg/dL/h) (52%) as in slow defibrinogenators (26%), with no increase in mortality or symptomatic ICH. Compared with a 20.7% incidence of symptomatic ICH in patients with mean post-9-hour fibrinogen levels less than or equal to 60 mg/dL, symptomatic ICH incidence was 0.8% in those with mean levels greater than 60 mg/dL (with no loss of efficacy). There were no symptomatic ICHs among 220 North American patients with mean levels greater than 70 mg/dL. It was hypothesized that an initial controlled rapid ancrod infusion with mean post-9-hour fibrinogen levels greater than 70 mg/dL would yield superior efficacy and safety. Such ESTAT patients had statistically significant efficacy versus placebo and a marked reduction in the incidence of symptomatic ICH versus patients taking ancrod with lower maintenance fibrinogen levels. CONCLUSION: Modifications to ancrod dosing may substantially improve efficacy while reducing the rate of symptomatic ICH.