Safety and immunogenicity of a 13-valent pneumococcal conjugate vaccine in healthy infants and toddlers given with routine pediatric vaccinations in Canada

Analysis of Adverse Events Post-13-Valent Pneumococcal Vaccination among Children in Hangzhou, China

With the widespread use of the 13-valent pneumonia vaccine (PCV13) in China, monitoring adverse events following immunization (AEFIs) is critical. We conducted a descriptive analysis of the AEFI occurrences reported within Hangzhou between the years 2020 and 2023, including the temporal trend of case reports and variables such as sex, age, type of PCV13, dose number, type of reporter, cause-specific classification, severity, and onset from vaccination. Vaccine safety signals were analyzed using reporting odds ratios (RORs). Over the 4 years analyzed in the study, 2564 AEFI cases were reported, including seven severe cases. Most AEFIs occurred within 0-1 days after vaccination (2398, 93.53%), with over half affecting infants aged 1.5-6 months of age. No statistically significant difference was observed between PCV13-TT and PCV-CRM197. Seasonal differences in AEFI reports were noted. Positive signals were detected for fever (ROR-1.96SE: 1.64) and persistent crying (ROR-1.96SE: 1.61). Four serious AEFI cases were coincidental events, while three others were considered vaccine-related cases (including one case each of allergic reaction, febrile seizure, and thrombocytopenia). The safety and tolerability of PCV13 are good, and attention should be paid to severe AEFIs, as well as long-term safety disparities between different types of PCV13.

Immunogenicity and seroefficacy of 10-valent and 13-valent pneumococcal conjugate vaccines: a systematic review and network meta-analysis of individual participant data

Background

Vaccination of infants with pneumococcal conjugate vaccines (PCV) is recommended by the World Health Organization. Evidence is mixed regarding the differences in immunogenicity and efficacy of the different pneumococcal vaccines.

Methods

In this systematic-review and network meta-analysis, we searched the Cochrane Library, Embase, Global Health, Medline, clinicaltrials.gov and trialsearch.who.int up to February 17, 2023 with no language restrictions. Studies were eligible if they presented data comparing the immunogenicity of either PCV7, PCV10 or PCV13 in head-to-head randomised trials of young children under 2 years of age, and provided immunogenicity data for at least one time point after the primary vaccination series or the booster dose. Publication bias was assessed via Cochrane's Risk Of Bias due to Missing Evidence tool and comparison-adjusted funnel plots with Egger's test. Individual participant level data were requested from publication authors and/or relevant vaccine manufacturers. Outcomes included the geometric mean ratio (GMR) of serotype-specific IgG and the relative risk (RR) of seroinfection. Seroinfection was defined for each individual as a rise in antibody between the post-primary vaccination series time point and the booster dose, evidence of presumed subclinical infection. Seroefficacy was defined as the RR of seroinfection. We also estimated the relationship between the GMR of IgG one month after priming and the RR of seroinfection by the time of the booster dose. The protocol is registered with PROSPERO, ID CRD42019124580.

Findings

47 studies were eligible from 38 countries across six continents. 28 and 12 studies with data available were included in immunogenicity and seroefficacy analyses, respectively. GMRs comparing PCV13 vs PCV10 favoured PCV13 for serotypes 4, 9V, and 23F at 1 month after primary vaccination series, with 1.14- to 1.54- fold significantly higher IgG responses with PCV13. Risk of seroinfection prior to the time of booster dose was lower for PCV13 for serotype 4, 6B, 9V, 18C and 23F than for PCV10. Significant heterogeneity and inconsistency were present for most serotypes and for both outcomes. Two-fold higher antibody after primary vaccination was associated with a 54% decrease in risk of seroinfection (RR 0.46, 95% CI 0.23-0.96).

Interpretation

Serotype-specific differences were found in immunogenicity and seroefficacy between PCV13 and PCV10. Higher antibody response after vaccination was associated with a lower risk of subsequent infection. These findings could be used to compare PCVs and optimise vaccination strategies.

Funding

The NIHR Health Technology Assessment Programme.

Surveillance of adverse events following immunization of 13-valent pneumococcal conjugate vaccine among infants, in Zhejiang province, China

OBJECTIVES

To evaluate the safety of 13-valent pneumococcal conjugate vaccine (PCV13) after its licensure.

METHODS

Review and describe the AEFI reported to national adverse event following immunization surveillance system (NAEFISS) in Zhejiang province from 2017 to 2020. Reporting rates of AEFI were calculated by age, city, severity of AEFI, categories of AEFI, and reaction categories. The data mining algorithm used in this study was reporting odds ratio (ROR). A value of ROR-1.96SE >1 (standard error [SE]) was considered as the positive signal.

RESULTS

NAEFISS received 3332 AEFI cases following PCV13, with a reporting rate of 17.58/10000 doses. Of the reported AEFI, 652 were serious AEFI cases and the reporting rate was 3.44 for serious AEFI. The reporting rate of fever was the highest among all the clinical diagnosis (7.39/10000 doses). The positive signals were obtained for injection site reaction (ROR-1.96SE: 1.55), hypotonic hyporesponsive episode (HHE) (ROR-1.96SE: 1.62) and febrile seizure (ROR-1.96SE: 1.52).

CONCLUSION

The present results supported previous observations that the PCV13 administered as the four-dose schedule was generally well tolerated in Chinese infants as we did not identify any new/unexpected safety concern from the NAEFISS during a four-year time period.

Vaccine effectiveness of the 7-valent and 13-valent pneumococcal conjugate vaccines in Canada: An IMPACT study

We used an indirect cohort analysis in children under 5 years-old from 2002 to 2018 to examine vaccine effectiveness (VE) of the 7-valent pneumococcal conjugate vaccine (PCV) (3 + 1 doses in most regions) and the 13-valent PCV (2 + 1 doses in all regions) against invasive pneumococcal disease (IPD) caused by vaccine serotypes in children in Canada. Cases were identified from the Canadian Immunization Monitoring Program ACTive (IMPACT), a national active surveillance network of 12 tertiary care pediatric hospitals that represent about 90% of tertiary care hospital beds in Canada. There were 1477 children evaluated for PCV7 VE and 489 for PCV13 VE. PCV7 VE in children with vaccination up to date for their age was 96% (95% CI: 67-99%) after a single dose and 95% (95% CI: 92-97%) after ≥2 doses. The VE was 91% (95% CI: 85-94%) in children who had received doses but were not up to date for their age. PCV13 VE in children with vaccinations up to date for their age was 55% (95% CI: 28-72%) after ≥2 doses. The PCV13-vaccine serotypes causing breakthrough IPD in children up to date for their age with 2+ doses of PCV13 were 3 (13/27, 48.2%),19A (11/27, 40.7%), and 19F (3/27, 11.1%). When serotype 3 and 19A were excluded, the VE of PCV13 against the remaining vaccine serotypes was 89% (95% CI: 64-97%) in children with ≥2 doses. The lower VE of PCV13 may be due to lower effectiveness against serotypes 3 and 19A, which could be influenced by the change in dosing schedule from 4 to 3 total doses with the introduction of PCV13, combined with vaccine uptake of 80%. However, PCV13 still provides the benefit of protection against more serotypes than PCV7, and good VE against all serotypes except 3 and 19A.

Failures of 13-Valent Conjugated Pneumococcal Vaccine in Age-Appropriately Vaccinated Children 2-59 Months of Age, Spain

Vaccination with the 13-valent conjugated pneumococcal disease (PCV13) has reduced invasive pneumococcal disease (IPD), but there have been reports of vaccine failures. We performed a prospective study in children aged 2–59 months who received diagnoses of IPD during January 2012–June 2016 in 3 pediatric hospitals in Catalonia, Spain, a region with a PCV13 vaccination coverage of 63%. We analyzed patients who had been age-appropriately vaccinated but who developed IPD caused by PCV13 serotypes. We detected 24 vaccine failure cases. The serotypes involved were 3 (16 cases); 19A (5 cases); and 1, 6B, and 14 (1 case each). Cases were associated with children without underlying conditions, with complicated pneumonia (OR 6.65, 95% CI 1.91–23.21), and with diagnosis by PCR (OR 5.18, 95% CI 1.84–14.59). Vaccination coverage should be increased to reduce the circulation of vaccine serotypes. Continuous surveillance of cases of IPD using both culture and PCR to characterize vaccine failures is necessary.

Incidence trends of parapneumonic pleural effusions/empyema in children 2009 to 2018 from health insurance data: Only temporal reduction after the introduction of PCV13

BACKGROUND

Recently, emergence of a higher proportion of serotype 3 in children with parapneumonic pleural effusion/empyema (PPE/PE) were observed in Germany despite general immunization with 13-valent pneumococcal conjugate vaccine (PCV13) since 2009. The impact of PCV13 on the overall incidence of PPE/PE in children is unclear.

METHODS

Annual incidence of PPE/PE in children were determined using secondary health care data for 2009-2018, provided by the Barmer statutory health insurer, serving about 11% of the German population. Temporal trends of the annual incidence were modelled applying generalized additive models.

RESULTS

Overall incidence of PPE/PE in children ( ≤18 years) in the ten-year observation period was 18.17 per 100,000. The 0-1 year olds showed the highest incidence (43.09 per 100 000). PPE/PE incidence decreased from 2009 until 2013 (nadir 2013 was 15.36; 95% CI: 13.41-17.31). Since 2013, the data show an annual increase. The nadir of incidence for the 2-5 year olds (15.85; 95% CI: 11.27-20.43) and the 6-18 year olds (12.29; 95% CI: 10.23-14.36) was also in 2013, whereas for the 0-1 year olds it was found in 2014 (32.66; 95% CI: 23.79-41.54). The GAM across all age groups showed a nearly U-shaped curve between time and incidence of PPE/PE by calendar year (p-non-linear = 0.0017). The model confirms the nadir in the year 2013.

DISCUSSION

We found a nonlinear temporal trend of PPE/PE incidence in children with a decrease from 2009 to 2013 and a subsequent increase until 2018. The former might be explained by a quasi elimination of serotype 1, the latter by an increase in the proportion of serotype 3 as demonstrated in German surveillance data of pediatric PPE/PE cases generated during the same observation period.

Hospital incidence, in-hospital mortality and medical costs of pneumococcal disease in Spain (2008-2017): a retrospective multicentre study

OBJECTIVE

The aim of this study was to analyze the characteristics of the patients attended with a pneumococcal disease in Spanish hospitals, to evaluate trends in hospital incidence and in-hospital mortality and to quantify patients' use of resources and medical costs.

METHODS

Medical admission records of patients admitted due to pneumococcal disease between 1 January 2008 and 31 December 2017 were obtained from a Spanish hospital discharge database. Records were identified with the International Statistical Classification of Diseases and Related Health Problems, 9th and 10th version codes corresponding to pneumococcal pneumonia, bacteraemia, pyogenic arthritis, endocarditis, meningitis, peritonitis and unspecified pneumococcal infections.

RESULTS

Admissions of 168,074 patients were analyzed, with a mean age of 63.5 years (median = 72; interquartile range = 28). Pneumococcal pneumonia was responsible for 64.1% of all admissions, with a hospital incidence of 31.1 per 10,000 patients that decreased significantly over the study period (p = .002). Hospital incidence of meningitis also displayed a decreasing trend over the study period (p = .003), whereas incidence of bacteraemia and pyogenic arthritis increased significantly (p = .001; p = .004). Mean Charlson Comorbidity Index was 3.3 (standard deviation = 2.2). In-hospital mortality was 7.0% over the study period, being the highest in patients admitted with endocarditis (17.2%). Sepsis, acute renal failure, disorders of fluid electrolyte and acid-base balance, heart failure and acute respiratory failure were strongly associated with in-hospital mortality. Mean length of hospital stay was of 11.1 days (median = 22; interquartile range = 26) and there was a majority of urgent admissions (95.0%); the most extended stays were registered in patients with endocarditis, meningitis and pyogenic arthritis. The mean hospital admission cost was €5676, €104.2 million annually for all registered patients; 50.3% of all costs were associated with pneumonia, whereas the highest admission costs were registered in patients with endocarditis (€15,991) and meningitis (€11,934). Mean admission costs increased significantly over the study period for pneumonia and bacteraemia and decreased for endocarditis.

CONCLUSIONS

The incidence of pneumococcal pneumonia and meningitis decreased over the study period after the introduction of vaccination in Spain. The advanced age of patients and presence of chronic comorbid conditions that are associated to in-hospital mortality must be taken into account when improving care protocols and upcoming vaccination plans.

Serotype and clonal distribution dynamics of invasive pneumococcal strains after PCV13 introduction (2011-2016): Surveillance data from 23 sites in Catalonia, Spain

Background

The objective of this study is to describe incidence and shifts of serotype and clonal distribution of invasive Streptococcus pneumoniae strains in four different age groups (<5 years, 5–17 years, 18–64 years and >65 years) during a period of intermediate PCV13 vaccination coverage (2011–2016) in Catalonia, Spain.

Methods

We included all pneumococcal strains systematically sent to the Catalan support laboratory for molecular surveillance of invasive pneumococcal disease (IPD) located at Hospital Sant Joan de Deu, Barcelona. Two study periods were considered: 2011–13, early PCV13 vaccination period (EVP) and 2014–2016, late vaccination period (LVP).

Results

A total of 2142 strains were included in the study. Five years after intermediate introduction of PCV13 in our population, a significant decrease of overall incidence of IPD in children <5 years was observed (incidence rate ratio 0.5, 95% confidence interval 0.4–0.8). However, in seniors older than 65 years, a significant increase of overall incidence of IPD was observed (IRR 1.4, 95% CI 1.1–1.7). The contribution of PCV13 vaccine serotypes to IPD declined significantly in all age groups: from 59% to 38.1% in <5 years; 82.7% to 59% in 5–17 years, 47.8% to 34.1% in 18–64 years and 48.2% to 37% in >65 years. Results found when comparing both periods were consistent with IRRs observed year by year. In children <5 years, the three major serotypes detected were 1, 24F and 19A in EVP vs 24F, 14 and 10A in LVP. Among patients 5–17 years the first three serotypes were 1, 12F and 14 both in EVP and LVP. Among adults 18–64, the three major serotypes detected were 1, 12F and 8 vs 8, 12F and 3, respectively. Finally, in patients >65 years the most frequently isolated serotypes were 3, 19A and 7F vs 3, 14 and 12F, respectively. Regarding clonal complexes (CCs) expressing mainly PCV13 serotypes, significant decreases of the proportions of CC306, CC191 and CC320 were observed, while CC156 showed a significant increase. As for CCs expressing mostly non-PCV13 serotypes, significant increases in ST989, CC53 and CC404 were showed.

Conclusions

Despite low vaccine coverage in our setting a significant decrease of incidence of IPD was observed in children younger than 5 years. The modest indirect protection against vaccine serotypes causing IPD in elderly indicate the need for the inclusion of more serotypes in future high-valent PCV and vaccinating old adults should be considered.

Increase in Streptococcus pneumoniae serotype 3 associated parapneumonic pleural effusion/empyema after the introduction of PCV13 in Germany

INTRODUCTION

Pediatric pneumococcal pneumonia complicated by parapneumonic pleural effusion/empyema (PPE/PE) remains a major concern despite general immunization with pneumococcal conjugate vaccines (PCVs).

METHODS

In a nationwide pediatric hospital surveillance study in Germany we identified 584 children <18 years of age with bacteriologically confirmed PPE/PE from October 2010 to June 2018. Streptococcus pneumoniae was identified by culture and/or PCR of blood samples and/or pleural fluid and serotyped.

RESULTS

S. pneumoniae was identified in 256 of 584 (43.8%) children by culture (n = 122) and/or PCR (n = 207). The following pneumococcal serotypes were detected in 114 children: serotype 3 (42.1%), 1 (25.4%), 7F (12.3%), 19A (7.9%), other PCV13 serotypes (4.4%) and non-PCV13 serotypes (7.9%). Between October 2010 and June 2014 serotype 1 (38.1%) and serotype 3 (25.4%) were most prevalent, whereas between July 2014 and June 2018 serotype 3 (62.7%) and non-PCV13 serotypes (15.7%) were dominant. Compared to children with other pneumococcal serotypes, children with serotype 3 associated PPE/PE were younger (median 3.2 years [IQR 2.1-4.3 years] vs. median 5.6 years [IQR 3.8-8.2 years]; p < 0.001) and more frequently admitted to intensive care (43 [89.6%] vs. 48 [73.8%]; p = 0.04). Seventy-six of 114 (66.7%) children with pneumococcal PPE/PE had been vaccinated with pneumococcal vaccines. Thirty-nine of 76 (51.3%) had received a vaccine covering the serotype detected. Thirty of these 39 breakthrough cases were age-appropriately vaccinated with PCV13 and considered vaccine failures, including 26 children with serotype 3, three children with serotype 19A and one child with serotype 1.

CONCLUSION

Following the introduction of PCV13 in general childhood vaccination we observed a strong emergence of serotype 3 associated PPE/PE in the German pediatric population, including a considerable number of younger children with serotype 3 vaccine breakthrough cases and failures. Future PCVs should not only cover newly emerging serotypes, but also include a more effective component against serotype 3.

Immunogenicity And Safety Of The 13-Valent Pneumococcal Conjugate Vaccine In Patients With Monoclonal Gammopathy Of Undetermined Significance - Relationship With Selected Immune And Clinical Parameters

Purpose

Patients with monoclonal gammopathy of undetermined significance (MGUS) have an increased risk of developing infections. Streptococcus pneumoniae vaccinations are recommended for immunocompromised patients, including patients with lymphoproliferative disorders such as MGUS. The objective of the study was to assess the immune response to the 13-valent pneumococcal conjugate vaccine (PCV13) in treatment-naive MGUS patients versus healthy subjects. All study groups were evaluated for the levels of specific pneumococcal antibodies, the levels of IgG and IgG subclasses, and selected peripheral blood lymphocyte subpopulations, including the proportion of plasmablasts before and after immunization.

Patients and methods

A total of 22 previously untreated patients with MGUS and 15 healthy age- and sex-matched volunteers were included in the study. All participants were immunized with PCV13 Prevenar13 (Pfizer). The following parameters were assessed: 1) serum-specific pneumococcal antibody titers before and 30 days after vaccination, 2) percentage of plasmablasts, defined as CD19+/IgD-/CD27++, before and 7 days after vaccination, 3) serum total IgG and IgG1, IgG2, IgG3, IgG4 levels before and 30 days after vaccination.

Results and conclusion

PCV13 vaccination in MGUS patients is safe and effectively protects against S. pneumoniae infection. In unvaccinated individuals, vaccination should be carried out as soon as possible after diagnosis. It can protect patients against serious infectious complications, which can contribute to extending the time to progression and transformation into more aggressive diseases. PCV13 vaccination is more effective in MGUS patients with a lower concentration of M protein. Serum M protein concentration in patients diagnosed with MGUS may be a useful predictor of the effectiveness of vaccination.

The Epidemiology and Biostatistics of Pneumococcus

Invasive infections caused by Streptococcus pneumoniae, such as pneumonia, meningitis, and bacteremia, are a major cause of morbidity and mortality in young children and older adults worldwide. The introduction of pneumococcal conjugate vaccines into national childhood immunization programs has led to large and sustained reductions in the incidence of invasive pneumococcal disease across all age groups. Here we describe the epidemiology and biostatistics of pneumococcal disease as well as the impact of vaccination on the burden of pneumococcal disease globally.

Prevention of Invasive Pneumococcal Disease: Problems Emerged After Some Years of the 13-Valent Pneumococcal Conjugate Vaccine Use

Starting from 2010, the 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in several countries. This paper discusses some of the problems recently emerged after PCV13 use and their clinical impact. The impact of PCV13 has been relevant and has saved millions of children and adults by severe infectious diseases. However, it seems likely that in the future, effectiveness of the vaccine might be even higher than that presently evidenced. This is because long-term administration of PCV13 to the pediatric population can favor a more extensive reduction of nasopharyngeal colonization with vaccine serotypes of both vaccinated and unvaccinated subjects and further reduce invasive pneumococcal disease in all the individuals (herd immunity). While waiting for new vaccines to be able to overcome the problem of a limited number of pneumococcal strains included in PCV13, it is recommended to increase pneumococcal vaccination coverage in the entire pediatric population.

Effectiveness of the 13-valent pneumococcal conjugate vaccine in preventing invasive pneumococcal disease in children aged 7-59 months. A matched case-control study

Background

The 13-valent pneumococcal conjugate vaccine (PCV13) was licensed based on the results of immunogenicity studies and correlates of protection derived from randomized clinical trials of the 7-valent conjugate pneumococcal vaccine. We assessed the vaccination effectiveness (VE) of the PCV13 in preventing invasive pneumococcal disease (IPD) in children aged 7–59 months in a population with suboptimal vaccination coverage of 55%.

Methods

The study was carried out in children with IPD admitted to three hospitals in Barcelona (Spain) and controls matched by hospital, age, sex, date of hospitalization and underlying disease. Information on the vaccination status was obtained from written medical records. Conditional logistic regression was made to estimate the adjusted VE and 95% confidence intervals (CI).

Results

169 cases and 645 controls were included. The overall VE of ≥1 doses of PCV13 in preventing IPD due to vaccine serotypes was 75.8% (95% CI, 54.1–87.2) and 90% (95% CI, 63.9–97.2) when ≥2 doses before 12 months, two doses on or after 12 months or one dose on or after 24 months, were administered. The VE of ≥1 doses was 89% (95% CI, 42.7–97.9) against serotype 1 and 86.0% (95% CI, 51.2–99.7) against serotype 19A. Serotype 3 showed a non-statistically significant effectiveness (25.9%; 95% CI, -65.3 to 66.8).

Conclusions

The effectiveness of ≥1 doses of PCV13 in preventing IPD caused by all PCV13 serotypes in children aged 7–59 months was good and, except for serotype 3, the effectiveness of ≥1 doses against the most frequent PCV13 serotypes causing IPD was high when considered individually.

Impact of Pneumococcal Conjugate Vaccines on Selected Head and Neck Infections in Hospitalized Israeli Children

BACKGROUND

Streptococcus pneumoniae is a major pathogen of pediatric head and neck infections (HNIs), for example, acute otitis media (AOM), acute mastoiditis, acute bacterial sinusitis and meningitis. The aim of this study was to characterize the epidemiology of pneumococcal HNIs (pHNIs) before, during and after the introduction of pneumococcal conjugate vaccines (PCVs).

METHODS

Children 0-16 years of age, who were hospitalized with HNIs in the pediatrics department in a general hospital between January 1, 2007, and December 31, 2014, were retrospectively identified. Study years were categorized according to the PCV introduction timeline: 2007-2008: "pre-PCV years"; 2009-2011: "transition years" and 2012-2014: "post-PCV years." pHNIs episodes were defined if pneumococcal culture or urine antigen was positive. Children who received ≥2 doses of PCV7/PCV13 were considered as immunized. All other children were considered as unimmunized.

RESULTS

HNIs accounted for 2.5%-4.7% of the total admissions; 3%-17% of them were pHNIs. Eighty-seven pHNI episodes were identified: AOM (n = 42), acute mastoiditis (n = 28) and meningitis (n = 17). There was a downward trend in the overall incidence of HNIs, and particularly of pHNIs, in the post-PCV years. The average age and hospitalization duration of children with HNIs/pHNIs remained stable during the study years. In 2009-2010, pHNIs incidence sharply decreased, from 7 to 1.74/1000 hospitalized children/year, due to ~55% reduction of pneumococcal AOM episodes. An additional decrease was observed in the post-PCV years (1.62/1000 hospitalized children/year). Immunized children were less likely to present with pHNIs (P = 0.001) but were more likely to undergo surgery (P = 0.042).

CONCLUSION

We observed a reduction in pHNIs incidence after PCV program implementation.

Invasive pneumococcal disease among adults in Japan, April 2013 to March 2015: disease characteristics and serotype distribution

BACKGROUND

In Japan, the clinical characteristics and recent serotype distribution among adult patients of invasive pneumococcal disease (IPD) have not been fully investigated since the introduction of the pneumococcal conjugate vaccine (PCV) in children. From November 2010, PCV7 was encouraged by an official program, funded by government, subsequently included in the routine schedule in April 2013, and replaced with a PCV13 in November 2013.

METHODS

Between April 2013 and March 2015, patients with IPD older than 15 years were evaluated based on the enhanced national surveillance in ten prefectures of Japan. The serotype distribution of the isolates was analyzed in these patients.

RESULTS

The analysis included 291 patients: 107 patients (37%) were female and the median age was 70 years. Of 281 patients with available data, 202 (72%) had underlying diseases, including 107 patients (38%) with immunocompromised status. The case fatality proportion for all case was 20%. In subgroup analysis, the case fatality proportion (29%) in immunocompromised patients was much higher than that (0-16%) in each age group of nonimmunocompromised patients (15-39 years, 40-64 years, and ≥ 65 years). While the proportion of bacteremia without any focus (27%) was higher than that (8-10%) in nonimmunocompromised patients, the proportions of vaccine types (PCV13, 32%; PPSV23, 51%) of the causative isolates were lower than those in each age group of nonimmunocompromised patients. Among 291 isolates, the most frequent serotypes were 3 (17%), 19A (13%), and 22F (10%). Twelve percent of the isolates were PCV7 serotypes, 46% were PCV13 serotypes, and 66% were PPSV23 serotypes.

CONCLUSIONS

The majority of adult patients of IPD had underlying diseases, including immunocompromised conditions. A low proportion (12%) of PCV7-type IPD was observed in this population where PCV7 for children had been included in the routine immunization schedule.

Vaccine Failures in Patients Properly Vaccinated with 13-Valent Pneumococcal Conjugate Vaccine in Catalonia, a Region with Low Vaccination Coverage

Vaccine failures occurring with 13-valent pneumococcal conjugate vaccine (PCV13) in 3 pediatric hospitals in Barcelona (2012-2013) are described. PCV13 vaccine failure was defined as the occurrence of an invasive pneumococcal infection in children properly vaccinated by PCV13. Among 84 patients with invasive pneumococcal infection, 32 had received at least one dose of PCV13. Seventeen of them had invasive pneumococcal infection produced by a PCV13 serotype. Among those, 9 patients were considered to have a PCV13 vaccine failure. Serotype 3 was isolated in 6 patients, serotype 19A in 2 and serotype 6B in 1.

Reduction of Streptococcus pneumoniae Colonization and Dissemination by a Nonopsonic Capsular Polysaccharide Antibody

Streptococcus pneumoniae colonization of the nasopharynx (NP) is a prerequisite for invasive pneumococcal disease (IPD). The marked reduction in IPD that followed the routine use of pneumococcal polysaccharide conjugate vaccines (PCVs) has been linked to reduced NP colonization with vaccine-included serotypes (STs), with the caveat that PCVs are less effective against pneumonia than against IPD. Although PCV-elicited opsonic antibodies that enhance phagocytic killing of the homologous ST are considered a key correlate of PCV-mediated protection, recent studies question this relationship for some STs, including ST3. Studies with monoclonal antibodies (MAbs) to the pneumococcal capsular polysaccharide (PPS) of ST3 (PPS3) have shown that nonopsonic, as well as opsonic, antibodies can each protect mice against pneumonia and sepsis, but the effect of these types of MAbs on NP colonization is unknown. In this study, we determined the effects of protective opsonic and nonopsonic PPS3 MAbs on ST3 NP colonization in mice. Our results show that a nonopsonic MAb reduced early NP colonization and prevented ST3 dissemination to the lungs and blood, but an opsonic MAb did not. Moreover, the opsonic MAb induced a proinflammatory NP cytokine response, but the nonopsonic MAb had an antiinflammatory effect. The effect of the nonopsonic MAb on colonization did not require its Fc region, but its antiinflammatory effect did. Our findings challenge the paradigm that opsonic MAbs are required to prevent NP colonization and suggest that further studies of the activity of nonopsonic antibodies could advance our understanding of mechanisms of PCV efficacy and provide novel correlates of protection.

Pneumococcal conjugate vaccines (PCVs) have markedly reduced the incidence of invasive pneumococcal disease (IPD). Vaccine-elicited pneumococcal polysaccharide (PPS) antibodies that enhance in vitro phagocyte killing of vaccine-included serotypes (STs) (opsonic antibodies) have been considered correlates of vaccine protection and are thought to exert their effect at the initial site of infection, the nasopharynx (NP). However, the data presented here show that this is not the necessarily the case. A nonopsonic PPS monoclonal antibody (MAb) reduced pneumococcal colonization and dissemination of its homologous ST in mice, but surprisingly, an opsonic PPS MAb to the same ST did not. These results reveal that PPS antibodies can work in different ways than previously thought, challenge the paradigm that opsonic antibodies are required to prevent IPD, and provide new insights into PCV efficacy that could lead to novel correlates of vaccine protection.

The impact of 10-valent and 13-valent pneumococcal conjugate vaccines on serotype 19A invasive pneumococcal disease

The circulation in the community of pneumococcal serotype 19A, a highly invasive and frequently extremely resistant pneumococcal strain, has increased the focus on methods to control its presence and effect. Two vaccines have been developed: the 10-valent pneumococcal conjugate vaccine (PCV10) and the 13-valent pneumococcal conjugate vaccine (PCV13). Available data indicate that PCV13 is highly effective in reducing the risk of serotype 19A invasive pneumococcal disease (IPD) in both vaccinated children and unvaccinated adults. Positive data have also been published for PCV10 that suggest that the conjugated serotype 19F included in the vaccine could evoke a cross-reactive antibody response with serotype 19A. However, a great number of invasive pneumococcal disease (IPD) cases are associated with serotypes not included in either of the vaccines, and preparation of a vaccine containing all the serotypes is unrealistic. Protein vaccines are the real future to definitively reduce the pneumococcal disease burden.

Pneumococcal conjugate vaccine-elicited antibody persistence and immunogenicity and safety of 13-valent pneumococcal conjugate vaccine in children previously vaccinated with 4 doses of either 7-valent or 13-valent pneumococcal conjugate vaccine

BACKGROUND

Pneumococcal conjugate vaccine (PCV) antibody persistence and immunologic memory responses may be indicative of protection in previously vaccinated children. In children vaccinated in a previous study with an infant/toddler regimen of 4 doses of PCV7, 4 doses of PCV13, or 3 doses of PCV7 (infant series) and a dose of PCV13 (toddler dose), this follow-on study evaluated antibody persistence ≥24 months after the toddler dose, and immunogenicity and safety of a follow-on dose of PCV13.

METHODS

Children ≥3 years of age who had completed the initial study received 1 dose of PCV13 in this phase 3, open-label follow-on study in France. Serotype-specific anticapsular immunoglobulin G (IgG) and functional opsonophagocytic activity (OPA) were compared across the previous study vaccination groups, before, 4-7 days (IgG only), and 1 month after follow-on vaccination. Safety was assessed.

RESULTS

Before follow-on vaccination, IgG and OPA levels for the PCV7 serotypes were comparable across vaccination groups, but were generally higher for the 6 additional serotypes in children who received PCV13 in the previous study. At both time points after the follow-on vaccination, IgG and OPA values for all 13 serotypes increased, those for the PCV7 serotypes were similar across vaccination groups, but concentrations for the additional serotypes were higher in children who had received PCV13 in the previous study. PCV13 was well-tolerated.

CONCLUSIONS

Antibody persistence and rapid responses after a follow-on dose of PCV13 suggest that even a single toddler dose of PCV13 is likely to provide protection against the 6 additional PCV13 serotypes.

Discovery of β-lactam-resistant variants in diverse pneumococcal populations

Understanding of antibiotic resistance in Streptococcus pneumoniae has been hindered by the low frequency of recombination events in bacteria and thus the presence of large linked haplotype blocks, which preclude identification of causative variants. A recent study combining a large number of genomes of resistant phenotypes has given an insight into the evolving resistance to β-lactams, providing the first large-scale identification of candidate variants underlying resistance.

Invasive pneumococcal infections in Vellore, India: clinical characteristics and distribution of serotypes

Background

Streptococcus pneumoniae infection is a serious problem worldwide and the case fatality rate remains high. The aim of this study was to analyze the distribution of pneumococcal serotypes causing invasive pneumococcal disease (IPD), to survey the potential coverage of present and future vaccines, and to investigate differences between serotypes and groups of serotypes with regard to manifestation, case fatality rate, age, and other risk factors.

Methods

Isolates from 244 consecutive patients with IPD were collected at the Christian Medical College, Vellore, India between January 2007 and June 2011, and clinical data were obtained retrospectively. Clinical characteristics were analyzed both for individual serotypes and for those grouped as “invasive”, “pediatric”, or “vaccine” serotypes.

Results

The serotype coverage for the pneumococcal conjugated vaccines (PCV) PCV7, PCV10, PCV13, PCV15, and pneumococcal polysaccharide vaccine (PPV) PPV23 was 29%, 53%, 64%, 66%, and 73%, respectively. The proportion of IPD caused by vaccine types was lower than pre-vaccination studies from other parts of the world. In adults, serotype 1 was mainly isolated from previously healthy patients without risk factors for IPD. This serotype caused more pneumonia and less meningitis than other serotypes, as was also noted for the “invasive” serotypes (1, 5, and 7 F).

Conclusions

The most common pneumococcal serotypes in this study behaved in similar ways to those in countries where the PCV has been introduced. Also, the most common serotypes in this study are included in the new PCVs. Therefore, a national program of childhood immunization with PCV10/13 in India is likely to be successful.

13-valent pneumococcal conjugate vaccine: a review of its use in infants, children, and adolescents

The 13-valent pneumococcal conjugate vaccine (Prevenar 13(®); Prevnar 13(®)) [PCV13] includes 13 serotype-specific polysaccharides of Streptococcus pneumoniae conjugated individually to non-toxic diphtheria CRM197 protein, thus providing wider coverage of pneumococcal serotypes than its 7-valent predecessor (PCV7). For pediatric populations, PCV13 was initially approved for use in infants and children up to 5 years of age, but recently received approval for expanded use (ages 6 weeks to 17 years) in the EU and the USA. This change in labeling was made primarily on the basis of results of Study 3011, which demonstrated the serotype-specific immunogenicity of a single dose of PCV13 in children ≥5 to <10 years of age who had previously received PCV7. Study 3011 also demonstrated functional immune responses after a single dose of PCV13 in a cohort ≥10 to <18 years of age who had not previously received PCV7. Importantly, prior to Study 3011, several randomized studies comparing PCV13 and PCV7 in infants and younger children demonstrated noninferiority of immune responses to the seven serotypes common to both vaccines after a two- or three-dose primary infant series and after the toddler booster dose; immunogenicity and functional immune responses were also demonstrated for the six additional serotypes. The safety and reactogenicity of PCV13 was generally similar to that of PCV7, and PCV13 did not interfere with the immune responses to coadministered routine pediatric vaccines. PCV13 is expected to substantially reduce the incidence of invasive pneumococcal diseases in a manner similar to that which occurred after PCV7 was introduced, and evidence of the protective effectiveness of PCV13 against pneumococcal diseases is emerging.

Safety and immunogenicity of 13-valent pneumococcal conjugate vaccine in infants: a meta-analysis

Pneumococcal infections are a major cause of morbidity and mortality worldwide. Pneumococcal conjugate vaccines represent major progress in the prevention of invasive pneumococcal disease in the paediatric population. We performed a meta-analysis, in accordance with the PRISMA statement, in order to assess the immunogenicity and safety of 13-valent pneumococcal conjugate vaccines in infants. A literary search was conducted using electronic databases and specialized journals were searched manually. Inclusion criteria were: clinical trials with infants vaccinated with 13-valent pneumococcal conjugate, compared to 7-valent vaccine. We recorded the results in terms of the immunogenicity and safety of the vaccines. The quality of the studies included was assessed using the CASP and Jadad checklists. We included nine randomized clinical trials of 258 potentially relevant references in the meta-analysis. The studies included had high-moderate quality. Both vaccines were well tolerated in all groups of infants, and most local reactions and systemic events were of mild or medium intensity and typical of any injected vaccine. All studies included in the meta-analysis showed high immunogenicity for both pneumococcal vaccines in all tested serotypes. An anti-polysaccharide antibody concentration of ≥0.35 μg/mL was achieved in at least 89% of the infants. Our results suggest that the 13-valent pneumococcal conjugate vaccine has a similar safety profile, and is as effective as, the 7-valent vaccine in the prevention of invasive pneumococcal disease caused by the seven common serotypes, and could provide expanded protection against the six additional serotypes.

Immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine in healthy infants in Japan

BACKGROUND

A 13-valent pneumococcal conjugate vaccine (PCV13) containing 6 additional serotypes not included in the 7-valent PCV has been developed to broaden protection against Streptococcus pneumoniae, which is responsible for over 500,000 deaths annually worldwide in children <5 years of age. This study in Japanese infants evaluated the immunogenicity and safety of PCV13 given subcutaneously, the standard route for infant vaccination in Japan.

METHODS

This phase 3, single-arm, open-label study was conducted at 25 sites. Subjects received PCV13 as a 3-dose infant series and a toddler dose. Parents/legal guardians recorded local reactions and systemic events after each vaccination. The proportion of subjects with serotype-specific antipneumococcal polysaccharide immunoglobulin (Ig)G antibody concentrations ≥0.35 µg/mL was calculated before and 1 month after the infant series and toddler dose.

RESULTS

A total of 193 subjects enrolled. The proportion of subjects achieving pneumococcal IgG antibody concentrations ≥0.35 µg/mL was ≥97.2% for all 13 pneumococcal serotypes 1 month after the infant series and 98.9-100% after the toddler dose. IgG geometric mean concentrations were 2.57-14.69 µg/mL after the infant series and 2.06-16.33 µg/mL after the toddler dose. IgG geometric mean concentrations increased from pre- to posttoddler dose by ≥2.8-fold, demonstrating a booster effect. Local reactions and fever were generally mild or moderate in severity.

CONCLUSIONS

PCV13 was immunogenic for all serotypes and had a favorable safety profile when administered subcutaneously to Japanese infants. PCV13 should offer broader serotype protection than 7-valent PCV in preventing pneumococcal disease in Japanese children.

Immune response to 13-valent pneumococcal conjugate vaccine with a reduced dosing schedule

BACKGROUND

The 7-valent pneumococcal conjugate vaccine (PCV7) has demonstrated effectiveness against pneumococcal illnesses when administered as 3 infant doses plus a toddler dose (3+1 schedule) or as an abbreviated schedule of 2 infant doses plus a toddler dose (2+1 schedule). The 13-valent pneumococcal conjugate vaccine (PCV13) is approved and World Health Organization-prequalified for administration in a 2+1 schedule when used as part of routine immunization programs.

OBJECTIVE

To summarize immunologic responses elicited by PCV13 administered in a 2+1 schedule and following 2 doses in a 3+1 schedule.

METHODS

Studies were double-blind, randomized, active-controlled, multicenter studies except the Mexico study (open-label, single-arm). In 2+1 studies, PCV13 was administered at 2, 4, and 12 (UK) or 3, 5, and 11 (Italy) months. In 3+1 studies (Spain and Mexico), assessment was made postdose 2 of the primary series (2, 4, and 6 months). The primary immunogenicity endpoint was the proportion of participants achieving serotype-specific antipolysaccharide immunoglobulin (Ig)G concentrations ≥ 0.35μg/mL (i.e., responders) 1 month postdose 2. Pneumococcal IgG geometric mean concentrations (GMCs), opsonophagocytic activity (OPA), and concomitant vaccine responses were assessed.

RESULTS

PCV13 and PCV7 elicited comparable immune responses for the 7 common serotypes after 2 infant doses. The proportion of PCV13 responders postdose 2 was >85% for most of the 7 common and 6 additional serotypes, except common serotypes 6B (27.9-81.4%) and 23F (55.8-77.5%) and additional serotypes 3 (73.8-96.9%) and 6A (79.2-94.4%). Serotypes 6B and 23F elicited lower IgG GMCs postdose 2 compared with other serotypes; all serotypes demonstrated boosting posttoddler dose. All serotypes demonstrated functional activity; >95% of participants achieved OPA levels ≥ 1:8 postdose 2. Concomitant vaccine responses were similar between PCV13 and PCV7 groups.

CONCLUSION

Immune responses elicited by PCV13 following 2 infant doses support transition from PCV7 to PCV13 in countries using a 2+1 schedule.

Protein carriers of conjugate vaccines: characteristics, development, and clinical trials

The immunogenicity of polysaccharides as human vaccines was enhanced by coupling to protein carriers. Conjugation transformed the T cell-independent polysaccharide vaccines of the past to T cell-dependent antigenic vaccines that were much more immunogenic and launched a renaissance in vaccinology. This review discusses the conjugate vaccines for prevention of infections caused by Hemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis. Specifically, the characteristics of the proteins used in the construction of the vaccines including CRM, tetanus toxoid, diphtheria toxoid, Neisseria meningitidis outer membrane complex, and Hemophilus influenzae protein D are discussed. The studies that established differences among and key features of conjugate vaccines including immunologic memory induction, reduction of nasopharyngeal colonization and herd immunity, and antibody avidity and avidity maturation are presented. Studies of dose, schedule, response to boosters, of single protein carriers with single and multiple polysaccharides, of multiple protein carriers with multiple polysaccharides and conjugate vaccines administered concurrently with other vaccines are discussed along with undesirable consequences of conjugate vaccines. The clear benefits of conjugate vaccines in improving the protective responses of the immature immune systems of young infants and the senescent immune systems of the elderly have been made clear and opened the way to development of additional vaccines using this technology for future vaccine products.

Immunogenicity, safety and tolerability of 3 lots of 13-valent pneumococcal conjugate vaccine given with routine pediatric vaccinations in the United States

BACKGROUND

The 7-valent pneumococcal conjugate vaccine (PCV7; serotypes 4, 6B, 9V, 14, 18C, 19F and 23F) has decreased invasive pneumococcal disease incidence. This study was performed to support licensure of a 13-valent pneumococcal conjugate vaccine (PCV13), which expands serotype coverage to include serotypes 1, 3, 5, 6A, 7F and 19A. This study assessed the immunogenicity, safety and manufacturing consistency of PCV13.

METHODS

Randomized, double-blind, multicenter trial. Healthy United States infants were randomized 2:2:2:1 to receive 1 of 3 lots of PCV13 or PCV7, along with routine US pediatric vaccines at ages 2, 4 and 6 months (infant series), and 12 months (toddler dose).

RESULTS

Among 1709 vaccinated infants, 1 month postinfant series and 1 month posttoddler dose, immunoglobulin G geometric mean concentrations (GMCs) were within 2-fold among the PCV13 lots, meeting equivalence criteria for all 13 serotypes. In a post hoc analysis, based on percent responders at ≥0.35 μg/mL postinfant series and immunoglobulin G GMC ratios postinfant series and posttoddler dose, noninferiority criteria were met for combined PCV13 lots compared with PCV7 for all common serotypes. Posttoddler dose immunoglobulin G GMCs were higher than postinfant series GMCs for all serotypes. Local reactions and fevers were generally mild; incidences of local reactions, systemic events and adverse events were generally similar between groups.

CONCLUSIONS

PCV13 can be manufactured in a manner that elicits consistent immune responses. PCV13 provides increased serotype coverage and immunogenicity that is noninferior to PCV7 and has a safety profile similar to PCV7 when given with routine pediatric vaccines.

Distribution of Streptococcus pneumoniae serotypes that cause parapneumonic empyema in Turkey

Streptococcus pneumoniae is the most common etiological cause of complicated pneumonia, including empyema. In this study, we investigated the serotypes of S. pneumoniae that cause empyema in children. One hundred fifty-six children who were diagnosed with pneumonia complicated with empyema in 13 hospitals in seven geographic regions of Turkey between 2010 and 2012 were included in this study. Pleural fluid samples were collected by thoracentesis and tested for 14 serotypes/serogroups using a Bio-Plex multiplex antigen detection assay. The serotypes of S. pneumoniae were specified in 33 of 156 samples. The mean age ± the standard deviation of the 33 patients was 6.17 ± 3.54 years (range, 0.6 to 15 years). All of the children were unvaccinated according to the vaccination reports. Eighteen of the children were male, and 15 were female. The serotypes of the non-7-valent pneumococcal conjugated vaccine (non-PCV-7), serotype 1, serotype 5, and serotype 3, were detected in eight (14.5%), seven (12.7%), and five (9.1%) of the samples, respectively. Serotypes 1 and 5 were codetected in two samples. The remaining non-PCV-7 serotypes were 8 (n = 3), 18 (n = 1), 19A (n = 1), and 7F/A (n = 1). PCV-7 serotypes 6B, 9V, 14, 19F, and 23F were detected in nine (16.3%) of the samples. The potential serotype coverages of PCV-7, PCV-10, and PCV-13 were 16.3%, 45.4%, and 60%, respectively. Pediatric parapneumonic empyema continues to be an important health problem despite the introduction of conjugated pneumococcal vaccines. Active surveillance studies are needed to monitor the change in S. pneumoniae serotypes that cause empyema in order to have a better selection of pneumococcal vaccines.

Immunogenicity and safety of a 13-valent pneumococcal conjugate vaccine in healthy infants and toddlers given with routine vaccines in India

BACKGROUND

The childhood burden of disease attributable to Streptococcus pneumoniae is particularly high in India. The immunogenicity and safety of 13-valent pneumococcal conjugate vaccine (PCV13) were compared with 7-valent pneumococcal conjugate vaccine (PCV7) in a randomized, active-controlled, double-blind trial conducted at 12 sites in India.

METHODS

Healthy infants received PCV13 or PCV7 at 6, 10, and 14 weeks of age (infant series) and at 12 months of age (toddler dose), along with routine pediatric vaccinations. Immunoglobulin G responses against the 13 pneumococcal serotypes were evaluated 1 month after the infant series and after the toddler dose. Pertussis and poliomyelitis immune responses were assessed 1 month after the infant series. Safety and tolerability also were assessed.

RESULTS

The immunogenicity results for the 7 common serotypes and the concomitant vaccines (whole-cell pertussis and oral poliovirus) were similar for subjects receiving PCV13 and subjects receiving PCV7. Immune responses to the 6 additional serotypes were higher in the PCV13 group compared with the PCV7 group. PCV13 and PCV7 had similar safety and tolerability profiles.

CONCLUSIONS

PCV13 has immunogenicity similar to PCV7 in response to the 7 common serotypes, and has generally higher immunogenicity in response to the 6 additional serotypes. PCV13 may provide added protection against pneumococcal disease caused by the additional 6 serotypes and does not interfere with immune responses to whole-cell pertussis and oral poliovirus vaccines. PCV13 has an acceptable safety profile in both infants and toddlers, comparable with that of PCV7.

Epidemiologic and clinical implications of second-generation pneumococcal conjugate vaccines

This review is based on published literature about some of the potential advantages and challenges of the second generation of pneumococcal conjugate vaccines, with special reference to 13-valent vaccine in children and adults.

The 13-valent pneumococcal conjugate vaccine for invasive pneumococcal disease in Alaska native children: results of a clinical trial

BACKGROUND

During 1996 to 2000, Alaska Native children aged <5 years from Yukon Kuskokwim Delta (YKD) had invasive pneumococcal disease (IPD) rates 10-fold higher than non-Alaska Native children (547/100,000/yr versus 56/100,000/yr). After 7-valent pneumococcal conjugate vaccine (PCV7) introduction, IPD rates decreased to 148 per 100,000 during 2001 to 2004, increasing to 426 per 100,000 during 2005 to 2007 due to non-vaccine serotype disease. In 2009, we evaluated safety, immunogenicity and impact of 13-valent PCV (PCV13) in YKD children.

METHODS

In a prelicensure open-label clinical trial, eligible YKD children aged <5 years were offered PCV13 as appropriate for age and prior PCV7 history. PCV13 impact was assessed using existing Alaska-wide IPD surveillance. Serotype-specific anti-pneumococcal IgG levels were measured postinfant series and posttoddler dose in a subset of subjects. Adverse events and serious adverse events were collected in all; local reactions and systemic events were collected in toddlers. All YKD children were offered licensed PCV13 when it became available.

RESULTS

Three hundred seventy-two subjects received PCV13 during the clinical trial and 3342 postlicensure (April 2010 to August 2011). Adverse events were typically mild, or generally consistent with common childhood illnesses. IgG levels following PCV13 were similar to other populations. In YKD children aged <5 years, 52 IPD cases (31 PCV13-serotype) occurred during 2005 to 2008 (399.0/100,000/yr) versus 9 (7 PCV13-serotype) during January 2009 to August 2011 (106.7/100,000/yr; P < 0.001). No PCV13-serotype cases occurred among PCV13 recipients (3680 person follow-up years).

CONCLUSIONS

PCV13-serotype IPD incidence declined significantly after PCV13 introduction. Although non-PCV13-serotype IPD also declined significantly, absence of PCV13-serotype IPD in children who received PCV13 suggests a protective vaccine effect.

Two cases of hemolytic uremic syndrome caused by Streptococcus pneumoniae serotype 3, one being a vaccine failure

We report two cases of Streptococcus pneumoniae-associated hemolytic uremic syndrome (SP-HUS) caused by serotype 3. One case occurred in an unvaccinated boy and 1 in a girl vaccinated with the 13-valent pneumococcal conjugate vaccine. SP-HUS must be considered in children, and conjugate vaccines may be less effective against serotype 3 than other serotypes.

Pneumococcal vaccines for children: a global public health priority

Pneumococcal conjugated vaccines have been recommended in children for over a decade in many countries worldwide. Here we review the development of pneumococcal vaccines with a focus on the two types currently available for children and their safety record. We discuss also the effect of vaccines, including the 13-valent pneumococcal conjugate vaccine, on invasive pneumococcal diseases in children, particularly bacteraemia, pneumonia and meningitis, as well as on mucosal disease and carriage. In regions where immunization was implemented in young children, the number of invasive pneumococcal diseases decreased significantly, not only in the target age group, but also in younger and much older subjects. Challenges and future perspectives regarding the development of new 'universal' vaccines, which could bypass the current problem of serotype-specific protection in a context of serotype replacement, are also discussed.

Development and clinical evaluation of Prevnar 13, a 13-valent pneumocococcal CRM197 conjugate vaccine

Pneumococcus is the leading cause of bacterial illness in children worldwide. The development, clinical evaluation, and postlicensure impact of the pneumococcal CRM(197) protein conjugate vaccine, PCV13, (Prevnar 13®) builds upon the excellent safety and substantial effectiveness of PCV7 (Prevnar®) in preventing pneumococcal disease in children. PCV13 adds pneumococcal serotypes 1, 3, 5, 6A, 7F, and 19A to serotypes 4, 6B, 9V, 14, 18C, 19F, 23F in PCV7 to provide comprehensive coverage for over 85% of epidemiologically important pneumococcal serotypes in the United States and throughout the world. PCV13 development required demonstration of immunologic responses to the 13 serotypes contained in the vaccine that were noninferior to the responses elicited by PCV7, and demonstration of a satisfactory safety profile. Studies were also performed to demonstrate compatibility with other childhood vaccines. Now licensed in many countries worldwide, PCV13 shows significant promise for expanded protection against pneumococcal disease in children.