Glycoconjugates: Synthesis, Functional Studies, and Therapeutic Developments

Glycoconjugates are major constituents of mammalian cells that are formed via covalent conjugation of carbohydrates to other biomolecules like proteins and lipids and often expressed on the cell surfaces. Among the three major classes of glycoconjugates, proteoglycans and glycoproteins contain glycans linked to the protein backbone via amino acid residues such as Asn for N-linked glycans and Ser/Thr for O-linked glycans. In glycolipids, glycans are linked to a lipid component such as glycerol, polyisoprenyl pyrophosphate, fatty acid ester, or sphingolipid. Recently, glycoconjugates have become better structurally defined and biosynthetically understood, especially those associated with human diseases, and are accessible to new drug, diagnostic, and therapeutic developments. This review describes the status and new advances in the biological study and therapeutic applications of natural and synthetic glycoconjugates, including proteoglycans, glycoproteins, and glycolipids. The scope, limitations, and novel methodologies in the synthesis and clinical development of glycoconjugates including vaccines, glyco-remodeled antibodies, glycan-based adjuvants, glycan-specific receptor-mediated drug delivery platforms, etc., and their future prospectus are discussed.

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.

Cost-Effectiveness and Budget Impact Analyses of Pneumococcal Vaccination in Indonesia

As a country with the high number of deaths due to pneumococcal disease, Indonesia has not yet included pneumococcal vaccination into the routine program. This study aimed to analyse the cost-effectiveness and the budget impact of pneumococcal vaccination in Indonesia by developing an age-structured cohort model. In a comparison with no vaccination, the use of two vaccines (PCV10 and PCV13) within two pricing scenarios (UNICEF and government contract price) was taken into account. To estimate the cost-effectiveness value, a 5-year time horizon was applied by extrapolating the outcome of the individual in the modelled cohort until 5 years of age with a 1-month analytical cycle. To estimate the affordability value, a 6-year period (2019-2024) was applied by considering the government's strategic plan on pneumococcal vaccination. In a comparison with no vaccination, the results showed that vaccination would reduce pneumococcal disease by 1,702,548 and 2,268,411 cases when using PCV10 and PCV13, respectively. Vaccination could potentially reduce the highest treatment cost from the payer perspective at $53.6 million and $71.4 million for PCV10 and PCV13, respectively. Applying the UNICEF price, the incremental cost-effectiveness ratio (ICER) from the healthcare perspective would be $218 and $162 per QALY-gained for PCV10 and PCV13, respectively. Applying the government contract price, the ICER would be $987 and $747 per QALY-gained for PCV10 and PCV13, respectively. The result confirmed that PCV13 was more cost-effective than PCV10 with both prices. In particular, introduction cost per child was estimated to be $0.91 and vaccination cost of PCV13 per child (3 doses) was estimated to be $16.61 and $59.54 with UNICEF and government contract prices, respectively. Implementation of nationwide vaccination would require approximately $73.3-$75.0 million (13-14% of routine immunization budget) and $257.4-$263.5 million (45-50% of routine immunization budget) with UNICEF and government contract prices, respectively. Sensitivity analysis showed that vaccine efficacy, mortality rate, and vaccine price were the most influential parameters affecting the ICER. In conclusion, pneumococcal vaccination would be a highly cost-effective intervention to be implemented in Indonesia. Yet, applying PCV13 with UNICEF price would give the best cost-effectiveness and affordability values on the routine immunization budget.

The influence of pneumococcal conjugate vaccine-13 on nasal colonisation in a controlled human infection model of pneumococcal carriage in Malawi: a double-blinded randomised controlled trial protocol

Streptococcus pneumoniae is the leading cause of morbidity and mortality due to community acquired pneumonia, bacterial meningitis and bacteraemia worldwide. Pneumococcal conjugate vaccines protect against invasive disease, but are expensive to manufacture, limited in serotype coverage, associated with serotype replacement, and demonstrate reduced effectiveness against mucosal colonisation.  For Malawi, nasopharyngeal carriage of vaccine-type pneumococci is common in vaccinated children despite national roll-out of 13-valent pneumococcal conjugate vaccine (PCV13) since 2011. Our team has safely transferred an established experimental human pneumococcal carriage method from Liverpool School of Tropical Medicine to the Malawi-Liverpool Wellcome Trust Clinical Research Programme, Malawi. This study will determine potential immunological mechanisms for the differential effects of PCV13 on nasal carriage between healthy Malawian and UK populations. We will conduct a double-blinded randomised controlled trial to vaccinate (1:1) participants with either PCV13 or control (normal saline). After a period of one month, participants will be inoculated with S. pneumoniae serotype 6B to experimentally induce nasal carriage using the EHPC method. Subsequently, participants will be invited for a second inoculation after one year to determine longer-term vaccine-induced immunological effects. Primary endpoint: detection of inoculated pneumococci by classical culture from nasal wash recovered from the participants after pneumococcal challenge. Secondary endpoints: local and systemic innate, humoral and cellular responses to PCV-13 with and without pneumococcal nasal carriage The primary objective of this controlled human infection model study is to determine if PCV-13 vaccination is protective against pneumococcal carriage in healthy adult Malawian volunteers. This study will help us to understand the observed differences in PCV-13 efficacy between populations and inform the design of future vaccines relevant to the Malawian population. Trial Registration: Pan African Clinical Trial Registry (REF: PACTR202008503507113).

The influence of pneumococcal conjugate vaccine-13 on nasal colonisation in a controlled human infection model of pneumococcal carriage in Malawi: a double-blinded randomised controlled trial protocol

Streptococcus pneumoniae is the leading cause of morbidity and mortality due to community acquired pneumonia, bacterial meningitis and bacteraemia worldwide. Pneumococcal conjugate vaccines protect against invasive disease, but are expensive to manufacture, limited in serotype coverage, associated with serotype replacement, and demonstrate reduced effectiveness against mucosal colonisation.  For Malawi, nasopharyngeal carriage of vaccine-type pneumococci is common in vaccinated children despite national roll-out of 13-valent pneumococcal conjugate vaccine (PCV13) since 2011. Our team has safely transferred an established experimental human pneumococcal carriage method from Liverpool School of Tropical Medicine to the Malawi-Liverpool Wellcome Trust Clinical Research Programme, Malawi. This study will determine potential immunological mechanisms for the differential effects of PCV13 on nasal carriage between healthy Malawian and UK populations. We will conduct a double-blinded randomised controlled trial to vaccinate (1:1) participants with either PCV13 or control (normal saline). After a period of one month, participants will be inoculated with S. pneumoniae serotype 6B to experimentally induce nasal carriage using the EHPC method. Subsequently, participants will be invited for a second inoculation after one year to determine longer-term vaccine-induced immunological effects. Primary endpoint: detection of inoculated pneumococci by classical culture from nasal wash recovered from the participants after pneumococcal challenge. Secondary endpoints: local and systemic innate, humoral and cellular responses to PCV-13 with and without pneumococcal nasal carriage The primary objective of this controlled human infection model study is to determine if PCV-13 vaccination is protective against pneumococcal carriage in healthy adult Malawian volunteers. This study will help us to understand the observed differences in PCV-13 efficacy between populations and inform the design of future vaccines relevant to the Malawian population. Trial Registration: Pan African Clinical Trial Registry (REF: PACTR202008503507113).

Pneumococcal Vaccination for Children in Asian Countries: A Systematic Review of Economic Evaluation Studies

Background: Evidence on costs and health benefits of pneumococcal conjugate vaccine (PCV) for children in Asian countries is limited but growing. As a region with a considerably high burden of pneumococcal disease, it is prominent to have a comprehensive overview on the cost-effectiveness of implementing and adopting a PCV vaccination program. Methods: We conducted a systematic review from Pubmed and Embase to identify economic evaluation studies of PCV for children in Asian countries up to May 2020. Data extraction included specific characteristics of the study, input parameters, cost elements, cost-effectiveness results, and key drivers of uncertainty. The Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) statement was followed for this systematic review. The reporting quality of the included studies was evaluated using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) statement. Results: After the screening process on both the title and abstract and full text of 518 records, a total of 25 studies fulfilled the inclusion criteria, and were included in the review. The majority of included studies demonstrates that PCV for children is cost-effective in most of the Asian region, and even cost-saving in some countries. Most of the included studies implemented cost utility analysis (CUA) using either quality-adjusted life years (QALYs) or disability-adjusted life years (DALYs). Overall, the main drivers affecting the cost effectiveness were vaccine price, burden regarding pneumonia-related parameters, and the inclusion of herd effects. Conclusion: The children pneumococcal vaccination program appears to be a cost-effective intervention in Asia, and even cost-saving in certain conditions. Vaccine price, pneumonia-related disease burden, and the inclusion of the herd effect are observed as important key drivers in estimating cost-effectiveness in this region. Incorporating PCV in vaccination programs in this region was found to be highly favorable.

Synthetic carbohydrate-based vaccines: challenges and opportunities

Glycoconjugate vaccines based on bacterial capsular polysaccharides (CPS) have been extremely successful in preventing bacterial infections. The glycan antigens for the preparation of CPS based glycoconjugate vaccines are mainly obtained from bacterial fermentation, the quality and length of glycans are always inconsistent. Such kind of situation make the CMC of glycoconjugate vaccines are difficult to well control. Thanks to the advantage of synthetic methods for carbohydrates syntheses. The well controlled glycan antigens are more easily to obtain, and them are conjugated to carrier protein to from the so-call homogeneous fully synthetic glycoconjugate vaccines. Several fully glycoconjugate vaccines are in different phases of clinical trial for bacteria or cancers. The review will introduce the recent development of fully synthetic glycoconjugate vaccine.

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 Administered in a 3 + 1 versus 2 + 1 Dose Schedule Among Infants in China

BACKGROUND

13-valent pneumococcal conjugate vaccine (PCV13) was licensed in China based on immunologic noninferiority to 7-valent PCV (PCV7). As part of the noninferiority study, immunogenicity and safety of PCV13 administered as a 3- or 2-dose infant series followed by a toddler dose were examined in healthy Chinese infants.

METHODS

Infants (42- to 77-days-old) were randomized to a 3-dose PCV13 or PCV7 infant series administered double-blind at 3, 4 and 5 months or PCV13 administered open-label at 2, 4 and 6 months and a 2-dose open-label series at 3 and 5 months; all subjects received a toddler dose (12 months). Serotype-specific immunoglobulin G (IgG) concentrations were measured 1 month after the infant series and before and after the toddler dose. Opsonophagocytic activity (OPA) was measured in a subset of subjects at each time point. Safety was evaluated.

RESULTS

One month after the infant series, serotype-specific immune responses (IgG ≥ 0.35 µg/mL) were similar for the 2- versus 3-dose schedules, except for serotype 6B, which was significantly lower in the 2-dose group [70.1% in the PCV13 (3, 5 + 12 mo) group vs. 93.2% in the PCV13 (3, 4, 5 + 12 mo) group and 94.7% in the PCV13 (2, 4, 6 + 12 mo) group]. IgG geometric mean concentrations and OPA geometric mean titers trended numerically higher with 3- versus 2-dose schedules. No significant differences in immunogenicity were observed between the 3- versus 2-dose schedules after the toddler dose. PCV13 was well-tolerated across all schedules.

CONCLUSIONS

PCV13 administered as a 3- or 2-dose infant series followed by a toddler dose was immunogenic and well tolerated in healthy Chinese infants and likely protective against PCV13 serotypes; immune responses with a 2-dose schedule were lower for some serotypes.

Impact of the 13-Valent Pneumococcal Conjugate Vaccine on Severe Invasive Disease Caused by Serotype 3 Streptococcus Pneumoniae in Italian Children

The effectiveness and impact of the 13-valent pneumococcal conjugate vaccine (PCV13) against invasive pneumococcal diseases (IPD) due to serotype 3 (ser3) has been questioned. However, the impact of PCV13 on different clinical presentations of ser3-IPD has not been studied so far. The impact of PCV13 on different clinical presentations of ser3-IPD in a population of Italian children aged 0–8 years was evaluated, comparing pre- and post-PCV13 introduction period. Real-time polymerase chain reaction (PCR) was used for the diagnosis and serotyping of IPD. During the observation period (1 January 2006–1 August 2018), ser3 was detected in 60/284 (21.1%) children under 8 with serotyped IPD. The incidence of sepsis and meningitis was 0.24 per 1,000,000 person-years (p-y) in pre-PCV13 and 0.02 per 1,000,000 p-y in post-PCV13. No cases occurred in vaccinated children. In the post-PCV13 period, case reduction was 13% for all ser3 IPD and 92% for sepsis and meningitis. Vaccination impact may be underestimated due to significant improvement in pneumococcal surveillance in post-PCVC13. Our data suggest a significant impact of PCV13 on meningitis and sepsis due to ser3 and a lower impact against pneumonia. While waiting for increasingly effective anti-pneumococcal vaccines, PCV13, which guarantees protection against the most severe clinical presentations of ser3-IPD, is currently the most effective prevention option available.

Immunogenicity and reactogenicity of ten-valent versus 13-valent pneumococcal conjugate vaccines among infants in Ho Chi Minh City, Vietnam: a randomised controlled trial

Background

Few data are available to support the choice between the two currently available pneumococcal conjugate vaccines (PCVs), ten-valent PCV (PCV10) and 13-valent PCV (PCV13). Here we report a head-to-head comparison of the immunogenicity and reactogenicity of PCV10 and PCV13.

Methods

In this parallel, open-label, randomised controlled trial, healthy infants from two districts in Ho Chi Minh City, Vietnam, were randomly allocated (in a 3:3:5:4:5:4 ratio), with use of a computer-generated list, to one of six infant PCV schedules: PCV10 in a 3 + 1 (group A), 3 + 0 (group B), 2 + 1 (group C), or two-dose schedule (group D); PCV13 in a 2 + 1 schedule (group E); or no infant PCV (control; group F). Blood samples were collected from infants between 2 months and 18 months of age at various timepoints before and after PCV doses and analysed (in a blinded manner) by ELISA and opsonophagocytic assay. The trial had two independent aims: to compare vaccination responses between PCV10 and PCV13, and to evaluate different schedules of PCV10. In this Article, we present results pertaining to the first aim. The primary outcome was the proportion of infants with an IgG concentration of at least 0·35 μg/mL for the ten serotypes common to the two vaccines at age 5 months, 4 weeks after the two-dose primary vaccination series (group C vs group E, per protocol population). An overall difference among the schedules was defined as at least seven of ten serotypes differing in the same direction at the 10% level. We also assessed whether the two-dose primary series of PCV13 (group E) was non-inferior at the 10% level to a three-dose primary series of PCV10 (groups A and B). This trial is registered with ClinicalTrials.gov, number NCT01953510.

Findings

Of 1424 infants screened between Sept 30, 2013, and Jan 9, 2015, 1201 were allocated to the six groups: 152 (13%) to group A, 149 (12%) to group B, 250 (21%) to group C, 202 (17%) to group D, 251 (21%) to group E, and 197 (16%) to group F. 237 (95%) participants in group C (PCV10) and 232 (92%) in group E (PCV13) completed the primary vaccination series and had blood draws within the specified window at age 5 months, at which time the proportion of infants with IgG concentrations of at least 0·35 μg/mL did not differ between groups at the 10% level for any serotype (PCV10–PCV13 risk difference −2·1% [95% CI −4·8 to −0·1] for serotype 1; −1·3% [–3·7 to 0·6] for serotype 4; −3·4% [–6·8 to −0·4] for serotype 5; 15·6 [7·2 to 23·7] for serotype 6B; −1·3% [–3·7 to 0·6] for serotype 7F; −1·6% [–5·1 to 1·7] for serotype 9V; 0·0% [–2·7 to 2·9] for serotype 14; −2·1% [–5·3 to 0·9] for serotype 18C; 0·0% [–2·2 to 2·3] for serotype 19F; and −11·6% [–18·2 to −4·9] for serotype 23F). At the same timepoint, two doses of PCV13 were non-inferior to three doses of PCV10 for nine of the ten shared serotypes (excluding 6B). Reactogenicity and serious adverse events were monitored according to good clinical practice guidelines, and the profiles were similar in the two groups.

Interpretation

PCV10 and PCV13 are similarly highly immunogenic when used in 2 + 1 schedule. The choice of vaccine might be influenced by factors such as the comparative magnitude of the antibody responses, price, and the relative importance of different serotypes in different settings.

Funding

National Health and Medical Research Council of Australia, and Bill & Melinda Gates Foundation.

Panproteome-wide analysis of antibody responses to whole cell pneumococcal vaccination

Pneumococcal whole cell vaccines (WCVs) could cost-effectively protect against a greater strain diversity than current capsule-based vaccines. Immunoglobulin G (IgG) responses to a WCV were characterised by applying longitudinally-sampled sera, available from 35 adult placebo-controlled phase I trial participants, to a panproteome microarray. Despite individuals maintaining distinctive antibody ‘fingerprints’, responses were consistent across vaccinated cohorts. Seventy-two functionally distinct proteins were associated with WCV-induced increases in IgG binding. These shared characteristics with naturally immunogenic proteins, being enriched for transporters and cell wall metabolism enzymes, likely unusually exposed on the unencapsulated WCV’s surface. Vaccine-induced responses were specific to variants of the diverse PclA, PspC and ZmpB proteins, whereas PspA- and ZmpA-induced antibodies recognised a broader set of alleles. Temporal variation in IgG levels suggested a mixture of anamnestic and novel responses. These reproducible increases in IgG binding to a limited, but functionally diverse, set of conserved proteins indicate WCV could provide species-wide immunity.

Clinical trial registration: The trial was registered with ClinicalTrials.gov with Identifier NCT01537185; the results are available from https://clinicaltrials.gov/ct2/show/results/NCT01537185.

Streptococcus pneumoniae is a bug that causes pneumonia and meningitis, killing around a million people each year. Vaccines now exist to protect young children against these diseases, but they are expensive and do not work against all the strains of the bacteria. This is because these shots train the body’s immune system to recognize and attack the bacterium’s capsule, a layer of sugars that surrounds the microbe and is often different between strains.

One possible solution could be a cheap, whole cell vaccine. These injections expose the body to genetically modified S. pneumoniae that do not carry the capsule. Such treatment has now been tested in a small number of people during a clinical trial.

Here, Campo et al. use a technique known as panproteome array to scan samples collected during this trial, and identify which elements the body learns to recognize when it is exposed to the genetically manipulated strain of S. pneumoniae. The results show that when volunteers receive this vaccine, their body targets proteins that the capsule normally shields from the immune system. Many of these proteins are very similar across all strains of S. pneumoniae, which means that the whole cell vaccine could potentially better protect against a broad spectrum of bacteria. However, further studies are needed to assess whether this is the case, especially in infants.

A Cost-Effectiveness Analysis of the 10-Valent Pneumococcal Non-Typeable Haemophilus influenzae Protein D Conjugate Vaccine (PHiD-CV) Compared to the 13-Valent Pneumococcal Conjugate Vaccine (PCV13) for Universal Mass Vaccination Implementation in New Zealand

OBJECTIVES

Invasive pneumococcal disease (IPD), pneumonia and acute otitis media (AOM) still represent a significant medical burden in children < 5 years of age in New Zealand (NZ), with marked disparities across socio-economic and ethnic groups. This cost-effectiveness evaluation aims to compare the potential impact of two childhood universal immunisation strategies: vaccination with a 3 + 1 schedule of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV, Synflorix, GSK) and the 13-valent pneumococcal conjugate vaccine (PCV13, Prevenar 13, Pfizer).

METHODS

A static Markov-process cohort model was used to simulate the epidemiological and economic burden of pneumococcal diseases on a single-birth cohort over its lifetime. Costs and outcomes were discounted annually at 3.5%. Epidemiological and cost inputs were extracted from the most recently available NZ data, or derived from the most relevant reference countries' sources. The most updated evidence on the efficacies of the corresponding vaccines were used, particularly the significant effectiveness for PHiD-CV against IPD caused by serotype 19A.

RESULTS

The model estimated that both vaccines have a broadly comparable impact on IPD-related diseases and pneumonia. Due to the additional benefits possible through broader impact on AOM, PHiD-CV is estimated to potentially provide additional discounted cost offsets of approximately NZD 0.8 million over the lifetime of the birth cohort.

CONCLUSIONS

To ensure health equity in children, given the substantial burden of pneumonia and AOM, decision-makers should also take into account the impact of PCVs on these diseases for decisions relating to routine infant immunization.

GSK STUDY IDENTIFIER

HO-15-16775.

Cost-effectiveness analysis of routine 13-valent pneumococcal conjugate vaccinations in Chinese infants

BACKGROUND

This study aimed to evaluate the cost-effectiveness of the 13-valent pneumococcal conjugate vaccine (PCV-13) compared to a no vaccination strategy in Chinese infants.

METHODS

A Markov process model was developed to examine the outcomes of PCV-13 against a no vaccination strategy using data and assumptions adapted for relevance to China. Outcomes over a lifetime horizon are presented. One-way and probabilistic sensitivity analyses were performed to determine the uncertainty.

RESULTS

Compared to no vaccination, a PCV-13 vaccination program would provide a gain of 0.009 additional quality-adjusted life years (QALYs) per subject. From the health care and societal perspectives, the incremental costs per QALY were $20,709 and 18,483, respectively. When herd effect was included, the cost effectiveness of the PCV-13 vaccination strategy was notably improved. The lower price of PCV-13 will improve the cost-effectiveness.

CONCLUSIONS

The PCV-13 vaccination is likely to be cost-effective at the current Chinese prices and ceiling threshold ($8,382).

Pneumococcal Vaccines - How Many Serotypes are Enough?

Streptococcus pneumoniae causes meningitis, pneumonia, septicemia, arthritis, sinusitis and otitis media specially in children and over 65 y age groups. It contributes significantly to under-five mortality and morbidity worldwide as well as in India. Use of pneumococcal vaccine seems to be the most effective measure to decrease the disease burden and reduction of under-five mortality. Many countries have already included Pneumococcal Conjugate Vaccines (PCV) in their National Immunization Programmes (NIP). Government of India has announced recently to include PCV13 in NIP in a phased manner. Superiority of a vaccine over the other depends upon serotype coverage, vaccine efficacy, cost effectiveness and safety profile. These facts will be discussed for the vaccines available in India. Further research is warranted to know the disease burden and develop vaccines to have more serotype coverage.

Immunogenicity and safety of a booster dose of the 13-valent pneumococcal conjugate vaccine in children primed with the 10-valent or 13-valent pneumococcal conjugate vaccine in the Czech Republic and Slovakia

BACKGROUND

Although both the 13-valent pneumococcal conjugate vaccine (PCV13) and the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) are widely used, it is unclear how interchangeable they are in terms of immunogenicity.

METHODS

Two phase 3, open-label, multicenter studies were conducted to assess the immunogenicity and safety of a booster dose of PCV13 in children primed with PHiD-CV or PCV13. In the Czech Republic, 12-15-month-old children received a PCV13 booster after 3-dose priming with either PHiD-CV or PCV13. In Slovakia, 11-12-month-old children received PCV13 following 2-dose priming with either PHiD-CV or PCV13. Serum IgG concentrations were assessed by enzyme-linked immunosorbent assay and functional antibodies were assessed by opsonophagocytic assay (OPA) before the booster and at 1 and 12months afterward. The primary objective of these studies was to assess non-inferiority of OPA titers for serotype 19A in PHiD-CV-primed subjects compared to those in PCV13-primed children 1month post-booster.

RESULTS

A total of 98 subjects in the Czech Republic and 89 subjects in Slovakia were included. One month after the PCV13 booster dose, the IgG and OPA immune responses to serotype 19A in subjects primed with 2 or 3 doses of PHiD-CV were non-inferior to those in subjects primed with PCV13. Non-inferior and persistent immune responses to most other vaccine serotypes were also observed after the PCV13 booster in PHiD-CV-primed subjects. No safety issues were raised in either study.

CONCLUSIONS

Overall, robust IgG and OPA immunological responses were observed after booster vaccination with PCV13 in children primed with 2 or 3 doses of PHiD-CV or PCV13, including for serotypes not included in PHiD-CV. These results suggest that these vaccines are interchangeable in terms of safety and immunogenicity and that PCV13 can be used as a booster in the context of mixed schedules. (EudraCT numbers: 2012-005366-35 and 2012-005367-27).

Immunogenicity of 13-valent pneumococcal conjugate vaccine among children with underlying medical conditions

BACKGROUND

Streptococcus pneumoniae is a leading cause of vaccine-preventable disease in children under 5years. Immunocompromised children and those with underlying diseases are at increased risk of severe complications from vaccine-preventable infections. We studied the humoral immune response to the 13-valent pneumococcal conjugate vaccine (PCV13) in children with HIV-infection, kidney or lung disease and compared this to the response in healthy control children.

METHODS

Children aged 12-71months with underlying conditions including HIV-infection and those with kidney and lung diseases (at-risk children), and a healthy control group were vaccinated with PCV13. The at-risk children received two doses of PCV13 and the controls received one dose. Serotype-specific antibodies for all PCV13 serotypes were measured by a luminex-based enzyme immunoassay at baseline and post-vaccination.

RESULTS

After the first PCV13 dose, the fold-increase in serotype-specific antibody geometric mean concentrations (GMCs) from baseline and the percentage of participants with ≥4-fold-increase in antibody concentrations was similar between the control and at-risk children. GMCs were, however, lower for three of the 13 serotypes in HIV-infected children, higher for serotype 6B in children with kidney disease and higher for serotypes 6B and 14 in children with lung disease. After second vaccine dose HIV-infected children had an increase in GMCs from post-first dose for nine serotypes but the percentage of participants with ≥4-fold-increase from baseline was similar post-second dose compared to post-first dose except for serotypes 6A and 19F. In children with kidney or lung diseases the immune responses after second vaccine dose were similar to post-first dose. Attenuated responses were observed for serotypes 3 and 19A in all study-groups, which was especially pronounced in the at-risk groups.

CONCLUSION

All study-groups mounted an immune response to PCV13, with the at-risk groups having responses that were mostly similar to the control children.

The Pneumocell-study: Vaccination of IgG1- and IgG2-deficient patients with Prevnar13

BACKGROUND

Patients with IgG-deficiency often suffer from repeated bacterial infections with S. pneumoniae. Since there is a lack of knowledge regarding whether IgG-deficient patients would benefit from conjugate pneumococcal vaccination, we set out to evaluate the effect of Prevnar13 vaccination in IgG₁- and/or IgG₂-deficient patients.

METHOD

We designed a small pilot-study including IgG₁- and/or IgG₂-deficient patients (n=10) and age- and sex-matched healthy controls (n=10). Serum, plasma and heparin-blood were collected prior to vaccination, as well as 1, 2 and 4weeks post vaccination, and the levels of opsonophagocytic activity (Opa) titers and anti-pneumococcal IgG-antibodies were analyzed.

RESULTS

Patients generally had lower Opa-titers than controls for most serotypes, but they exhibited an almost normal vaccine response to serotypes 6A and 6B. Notably, 5/10 patients showed vaccine-response to at least one serotype. Most patients reached the presumably protective levels of Opa-titers ≥8 and anti-pneumococcal IgG levels of 0.35µg/ml by 4weeks post-vaccination for a majority of the serotypes.

CONCLUSION

Our results show that vaccination of IgG-deficient patients with Prevnar13 is likely to have a clinical benefit. Our initial findings will provide a framework for future vaccine-trials in this vulnerable patient group. Registered at www.clinicaltrials.gov as NCT01847781.

Pneumococcal conjugate vaccine in HIV-infected and HIV-exposed, uninfected children

INTRODUCTION

Incidence of invasive pneumococcal disease (IPD) among HIV-infected children is 20-40 fold greater compared to HIV-uninfected children, including among HIV-infected children on antiretroviral therapy (ART). Also, HIV-exposed, uninfected children have 2.7-fold greater risk of IPD compared to HIV-unexposed children. Areas covered: We reviewed studies identified on Pubmed database with the terms 'PCV' and 'HIV'; studies involving adults only were excluded. Expert commentary: While ART and pneumococcal conjugate vaccines (PCV) have reduced IPD morbidity and mortality in HIV-infected children, ART-naïve and immunosuppressed children have inferior immunogenicity to most PCV serotypes; highlighting the need for concomitant use of ART with PCV. Furthermore, studies to determine optimal PCV dosing schedules, timing and number of doses, are urgently required to ensure sustained vaccine efficacy in HIV-infected children.

Safety, reactogenicity and immunogenicity of 2-dose catch-up vaccination with 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in Malian children in the second year of life: Results from an open study

Pneumonia is still the leading cause of death among African children with pneumococcal serotypes 1 and 5 being dominant in the below 5 y of age group. The present study assessed the safety, reactogenicity and immunogenicity of a 2-dose catch-up vaccination with the 10-valent pneumococcal non-typeable Haemophilus influenzae Protein D conjugate vaccine (PHiD-CV) in Malian children. This phase III, open-label study (NCT00985465) was conducted in Ouelessebougou, Mali, between November 2009 and July 2010. The study population consisted of PHiD-CV unprimed Malian children previously enrolled in the control group of study NCT00678301 receiving a 2-dose catch-up vaccination with PHiD-CV in the second year of life. Adverse events were recorded following each PHiD-CV dose. Antibody responses and opsonophagocytic activity (OPA) were measured pre-vaccination and after the second PHiD-CV catch-up dose. Swelling and fever (axillary temperature ≥ 37.5°C) were the most frequently reported solicited symptoms following either PHiD-CV dose. Few grade 3 solicited symptoms were reported. Large swelling reactions and serious adverse events were not reported. Post-catch-up vaccination, for each vaccine pneumococcal serotype, at least 94.7% of subjects had antibody concentrations ≥ 0.2 μg/ml, except for serotypes 6B (82.5%) and 23F (87.7%). At least 94.0% of subjects had OPA titres ≥ 8, except for serotype 19F (89.4%). The geometric mean concentration for antibodies against protein D was 839.3 (95% CI: 643.5-1094.6) EL.U/ml. Two-dose PHiD-CV catch-up regimen in the second year of life was well-tolerated and immunogenic for all vaccine pneumococcal serotypes and NTHi protein D when administered to Malian children

Direct, indirect and total effects of 13-valent pneumococcal conjugate vaccination on invasive pneumococcal disease in children in Navarra, Spain, 2001 to 2014: cohort and case–control study

We estimated the direct, indirect and total effects of the 13-valent pneumococcal conjugate vaccine (PCV13) on invasive pneumococcal disease (IPD) in children. A population-based cohort study followed children aged between 2.5 and 59 months between 2001 and 2014 in Navarra, Spain. IPD incidence was compared by PCV status and period. All cases diagnosed from July 2010 to December 2014 and eight matched controls per case were analysed to estimate the adjusted direct effect of PCV13. A total of 120,980 children were followed and 206 IPD cases were detected. Compared with unvaccinated children in the baseline period (2001–2004), overall IPD incidence in 2011–2014 (76% average PCV coverage) declined equally in vaccinated (total effect: 76%; hazard ratio (HR): 0.24; 95% confidence interval (CI): 0.14–0.40) and unvaccinated children (indirect effect: 78%; HR: 0.22; 95% CI: 0.09–0.55). IPD incidence from non-PCV13 serotypes increased among vaccinated children (HR: 2.84; 95% CI: 1.02–7.88). The direct effect of one or more doses of PCV13 against vaccine serotypes was 95% (odds ratio: 0.05; 95% CI: 0.01–0.55). PCV13 was highly effective in preventing vaccine-serotype IPD. The results suggest substantial and similar population-level vaccine benefits in vaccinated and unvaccinated children through strong total and indirect effects.

Pneumococcal conjugate vaccine introduction in Latin America and the Caribbean: progress and lessons learned

In Latin America and the Caribbean, pneumococcus has been estimated to cause 12,000-28,000 deaths, 182,000 hospitalizations, and 1.4 million clinic visits annually. Countries in the Americas have been among the first developing nations to introduce pneumococcal conjugate vaccines into their Expanded Programs on Immunization, with 34 countries and territories having introduced these vaccines as of September 2015. Lessons learned for successful vaccine introduction include the importance of coordination between political and technical decision makers, adjustments to the cold chain prior to vaccine introduction, and the need for detailed plans addressing the financial and technical sustainability of introduction. Though many questions on the Pneumococcal Conjugate Vaccine remain unanswered, the experience of the Americas suggests that the vaccines can be introduced quickly and effectively.

Immunogenicity and safety of 13-valent pneumococcal conjugate vaccine when administered to healthy Japanese adults aged ≥50 years. An open-label trial

This open-label study was designed to assess immunogenicity and safety of 13-valent pneumococcal conjugate vaccine (PCV13) when administered to Japanese adults aged ≥50 years not previously vaccinated with 23-valent pneumococcal polysaccharide vaccine and to compare this Japanese study population with similar study populations in the United States (US; 50–64 years age group) and European Union (EU; ≥65 years age group). Functional antibody immune responses were measured by opsonophagocytic activity assays. Immune responses in both Japanese age groups showed significant pre/postvaccination fold rises for each serotype. In the Japanese 50–64 years age group, immune responses for the majority of serotypes were significantly lower than in the ≥65 years Japanese age group and generally lower than in the 50–64 years age group in the US study. Immune responses in the Japanese ≥65 years age group were significantly higher for the majority of serotypes compared with the ≥65 years age group in the EU study. The safety profiles across age groups and studies were generally similar. In conclusion, PCV13 elicited robust immune responses in the Japanese study population. The unanticipated higher immune responses observed in the older age group in the Japanese study are of interest and of potential benefit given the higher incidence of pneumococcal disease in older adults. PCV13 was well tolerated and safe.

Safety, tolerability and immunogenicity of 15-valent pneumococcal conjugate vaccine in toddlers previously vaccinated with 7-valent pneumococcal conjugate vaccine

BACKGROUND

Widespread use of 7-valent pneumococcal conjugate vaccine (PCV7) in children has led to significant reduction in pneumococcal disease in children and adults. However, diseases caused by serotypes not included in PCV7 have increased. A 15-valent pneumococcal conjugate vaccine (PCV15) containing serotypes in PCV7 and 8 additional serotypes (1, 3, 5, 6A, 7F, 19A, 22F, 33F) was developed and evaluated in toddlers 12 to 15 months of age.

METHODS

Ninety toddlers who completed an infant series with PCV7 received a single dose of either aluminum-adjuvanted PCV15, nonadjuvanted PCV15, or PCV7. Injection-site and systemic adverse events (AEs) were collected for 14 days postvaccination and serious AEs (SAEs) were collected for 30 days postvaccination. Solicited AEs included local (pain/tenderness, swelling, nodule and redness) and systemic (fatigue, arthralgia and myalgia) AEs. Serotype-specific immunoglobulin G (IgG) and opsonophagocytic (OPA) responses were measured immediately prior and 30 days postvaccination.

RESULTS

Incidences of local and systemic AEs were comparable across vaccine groups. The majority of reported events, regardless of vaccine received, were transient and of mild to moderate intensity. No clinically significant differences were observed when comparing duration and severity of AEs. No vaccine-related SAEs or discontinuations from the study due to AEs were reported. Pneumococcal IgG concentrations and OPA titers increased postvaccination, with appreciable fold rises for all serotypes. Antibody levels were comparable between both PCV15 formulations and generally comparable to PCV7 for the shared serotypes.

CONCLUSION

Both formulations of PCV15 display acceptable safety profiles and induce IgG and OPA responses to all vaccine serotypes.

Chronic helminth infections impair pneumococcal vaccine responses

Pneumonia is the leading killer of children and disproportionately affects developing countries. Vaccination campaigns against Streptococcus pneumoniae, the leading cause of pneumonia, have recently been launched with a new conjugate vaccine in Africa. Using a mouse model, we assessed the potential role that the high burden of helminth infections in the countries targeted for vaccine might have on vaccine effectiveness. Mice vaccinated with either commercial conjugate or purified polysaccharide vaccines had impaired antibody responses if they were chronically infected with Taenia crassiceps. This translated to increased susceptibility to pneumococcal pneumonia and high mortality compared to helminth-negative vaccinated animals, which were fully protected from disease and death. Antibodies taken from Taenia-infected, vaccinated mice were unable to effectively opsonize S. pneumoniae for killing by alveolar macrophages, and did not protect against pneumococcal challenge when adoptively transferred into naïve animals. These data may have implications for vaccination programs in countries endemic with helminths.

Aetiology of paediatric pneumonia with effusion in the Dominican Republic and the potential impact of pneumococcal conjugate vaccines

Pleural effusion is a serious complication of pneumonia, and Streptococcus pneumoniae is a leading cause. We describe the aetiology of pneumonia with effusion among children in the Dominican Republic before the introduction of the 13-valent pneumococcal conjugate vaccine (PCV) in 2013 and the performance characteristics of a rapid immunochromatographic test (ICT) for detecting S. pneumoniae in pleural fluid. From July 2009 to June 2011, we enrolled children <15 years old admitted with pneumonia and pleural effusion to Robert Reid Cabral Children’s Hospital, Dominican Republic. Pleural fluid was tested by culture, polymerase chain reaction (PCR) for bacterial (S. pyogenes, S. pneumoniae) and viral (respiratory syncytial virus and human rhinovirus) pathogens, and by ICT for S. pneumoniae. We calculated the performance of ICT and culture compared with PCR. Among 121 cases, the median age was 31 months (range 1 week to 14 years). Pleural fluid culture (n = 121) and PCR testing (n = 112) identified an aetiology in 85 (70.2%) cases, including 62 S. pneumoniae (51.2%) and 19 Staphylococcus aureus (15.7%). The viruses tested were not detected. The most prevalent pneumococcal serotypes were 14 (n = 20), 1 (n = 13), and 3 (n = 12). Serotype coverage of the 10- and 13-valent PCVs would be 70.5% and 95.1%, respectively. The sensitivity of point-of-care ICT was 100% (95% confidence interval [CI] 94.1%–100%), while specificity was 86.3% (95% CI 73.7%–94.3%). S. pneumoniae caused more than half of paediatric pneumonia with effusion cases; introduction of PCV in the Dominican Republic could reduce the burden by 36–49%. ICT is a practical, valid diagnostic tool for clinical care and surveillance in settings with limited laboratory capacity.

Development of Streptococcus pneumoniae Vaccines Using Live Vectors

Streptococcus pneumoniae still causes severe morbidity and mortality worldwide, especially in young children and the elderly. Much effort has been dedicated to developing protein-based universal vaccines to conquer the current shortcomings of capsular vaccines and capsular conjugate vaccines, such as serotype replacement, limited coverage and high costs. A recombinant live vector vaccine delivering protective antigens is a promising way to achieve this goal. In this review, we discuss the researches using live recombinant vaccines, mainly live attenuated Salmonella and lactic acid bacteria, to deliver pneumococcal antigens. We also discuss both the limitations and the future of these vaccines.

A live-attenuated pneumococcal vaccine elicits CD4+ T-cell dependent class switching and provides serotype independent protection against acute otitis media

Acute otitis media (AOM) caused by Streptococcus pneumoniae remains one of the most common infectious diseases worldwide despite widespread vaccination. A major limitation of the currently licensed pneumococcal vaccines is the lack of efficacy against mucosal disease manifestations such as AOM, acute bacterial sinusitis and pneumonia. We sought to generate a novel class of live vaccines that (1) retain all major antigenic virulence proteins yet are fully attenuated and (2) protect against otitis media. A live vaccine candidate based on deletion of the signal recognition pathway component ftsY induced potent, serotype-independent protection against otitis media, sinusitis, pneumonia and invasive pneumococcal disease. Protection was maintained in animals coinfected with influenza virus, but was lost if mice were depleted of CD4(+) T cells at the time of vaccination. The live vaccine induced a strong serum IgG2a and IgG2b response that correlated with CD4(+) T-cell mediated class switching. Deletion of genes required for microbial adaptation to the host environment is a novel live attenuated vaccine strategy yielding the first experimental vaccine effective against pneumococcal otitis media.

Safety and immunogenicity of 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in Nigerian children: Booster dose and 2-dose catch-up regimens in the second year of life

In a previous study, 3-dose primary vaccination of Nigerian infants with the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) was immunogenic for vaccine pneumococcal serotypes, with comparable tolerability between PHiD-CV and control groups. In an open-label study (ClinicalTrials.gov, NCT01153893), 68 primed children received a PHiD-CV booster dose co-administered with a diphtheria-tetanus-acellular pertussis (DTPa) booster dose at 15–21 months and 36 children unprimed for pneumococcal vaccination received two PHiD-CV catch-up doses (first dose co-administered with DTPa booster dose) at 15–21 and 17–23 months. Adverse events were recorded and immune responses were measured before and one month after vaccination. In both groups, pain was the most frequent solicited local symptom and fever was the most frequent solicited general symptom after the booster dose and each catch-up dose. Few grade 3 solicited symptoms and no vaccine-related serious adverse events were reported. After booster vaccination, for each vaccine serotype, at least 98.5% of children had an antibody concentration ≥0.2 µg/ml and at least 94.0% had an opsonophagocytic activity (OPA) titer ≥8. After 2-dose catch-up, for each vaccine serotype, at least 97.1% had an antibody concentration ≥0.2 µg/ml, except for serotypes 6B (82.9%) and 23F (88.6%), and at least 91.4% had an OPA titer ≥8, except for serotypes 6B (77.4%) and 19F (85.3%). PHiD-CV induced antibody responses against protein D in both groups. In conclusion, PHiD-CV administered to Nigerian toddlers as a booster dose or 2-dose catch-up was well tolerated and immunogenic for vaccine pneumococcal serotypes and protein D.

Comparative immunogenicity and efficacy of 13-valent and 7-valent pneumococcal conjugate vaccines in reducing nasopharyngeal colonization: a randomized double-blind trial

BACKGROUND

The 13-valent pneumococcal conjugate vaccine (PCV13) was licensed to replace the 7-valent pneumococcal conjugate vaccine (PCV7) based on serological noninferiority criteria. To date no randomized PCV13 pediatric trial has included clinical endpoints.

METHODS

This randomized double-blind trial compared the impact of PCV13 versus PCV7 on nasopharyngeal (NP) colonization and immunogenicity. Healthy infants were randomized (1:1) to receive PCV7 or PCV13 at ages 2, 4, 6, and 12 months; NP swabs were collected at 2, 4, 6, 7, 12, 13, 18, and 24 months, and blood was drawn at 7 and 13 months. Rates of NP acquisition and prevalence, and serotype-specific immunoglobulin G (IgG) concentrations were assessed.

RESULTS

The per protocol analysis population included 881 PCV13 and 873 PCV7 recipients. PCV13 significantly reduced NP acquisition of the additional PCV13 serotypes 1, 6A, 7F, and 19A; the cross-reacting serotype 6C; and the common PCV7 serotype 19F. For serotype 3, and the other PCV7 serotypes, there were no significant differences between the vaccine groups. There were too few serotype 5 events to draw inference. The impact on prevalence at predefined time points was similar to that observed with NP acquisition. PCV13 elicited significantly higher IgG responses for PCV13 additional serotypes and serotype 19F, and similar or lower responses for 6/7 PCV7 serotypes.

CONCLUSIONS

PCV13 resulted in lower acquisition and prevalence of NP colonization than PCV7 did for 4 additional PCV13 serotypes, and serotypes 6C and 19F. It was comparable with PCV7 for all other common serotypes. These findings predict vaccine effectiveness through both direct and indirect protection.

CLINICAL TRIALS REGISTRATION

NCT00508742.

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.

Pneumococcal 13-valent conjugate vaccine for the prevention of invasive pneumococcal disease in children and adults

Pneumococcal disease remains a global problem despite the availability of effective conjugate vaccines. The 13-valent pneumococcal conjugate vaccine (PCV13) extends the valency of PCV7 by including six additional serotypes highly associated with invasive pneumococcal disease (IPD). Comparisons between PCV13 and PCV7 or the pneumococcal polysaccharide vaccine have established noninferiority of PCV13 for both safety and immunogenicity profiles for use in children and adults, respectively. At the end of 2011, PCV13 had been approved and launched in 104 countries worldwide, with 54 including the vaccine in their pediatric national immunization program. Surveillance data from early adopters of PCV13 has indicated reductions are occurring in both overall IPD and IPD caused by the six non-PCV7 serotypes; early reports of serotype replacement in carriage are also emerging. While serotype replacement for PCV7 was observed to varying degrees for both carriage and disease, the extent to which this will occur for PCV13 is yet to be determined.

Streptococcus pneumoniae--a review of carriage, infection, serotype replacement and vaccination

Invasive pneumococcal infection remains a leading global cause of morbidity and mortality in young children. In developed nations, a substantial decrease in the incidence of IPD has been achieved with inclusion of the 7 valent protein conjugated pneumococcal vaccines (7vPCV) into paediatric vaccine schedules. In contrast, the incidence of IPD has changed little in developing nations. This is likely due to poor access to medical care and pneumococcal vaccination, the accompanying HIV and malnutrition burden, and the fact that 7vPCV does not contain the most common serotypes (1,5, 6A) responsible for IPD in many developing nations. The battle against IPD in developed nations is not over, with the rise of non-7vPCV serotypes since routine 7vPCV vaccination. This has necessitated the development and distribution of pneumococcal vaccines containing 3 or 6 additional serotypes. This article provides an overview on pneumococcal carriage and risk factors for IPD, the rise of non-7vCPV serotypes in the era of 7vPCV vaccination, and the current and newly available broader valent pneumococcal vaccines.

Correlates of vaccine protection from influenza and its complications

Despite use of influenza vaccines for more than 65 y, influenza and its complications are a major cause of morbidity and mortality worldwide. Most deaths during influenza virus infections are due to underlying co-morbidities or secondary bacterial pneumonia. The measures of immune response currently used for licensure of influenza vaccines are relevant mainly for protection from viral infection in healthy adults. Development of new or improved influenza vaccines will require a definition of novel, and specific correlates of protection. These correlates should associate immune responses with outcomes that are relevant to specific risk groups, such as asthma exacerbation, hospitalization or disruptions to care or daily activities. Assessment of vaccine effectiveness for both viral and bacterial vaccines should include measures of impact on secondary bacterial pneumonia.

RrgB321, a fusion protein of the three variants of the pneumococcal pilus backbone RrgB, is protective in vivo and elicits opsonic antibodies

Streptococcus pneumoniae pilus 1 is present in 30 to 50% of invasive disease-causing strains and is composed of three subunits: the adhesin RrgA, the major backbone subunit RrgB, and the minor ancillary protein RrgC. RrgB exists in three distinct genetic variants and, when used to immunize mice, induces an immune response specific for each variant. To generate an antigen able to protect against the infection caused by all pilus-positive S. pneumoniae strains, we engineered a fusion protein containing the three RrgB variants (RrgB321). RrgB321 elicited antibodies against proteins from organisms in the three clades and protected mice against challenge with piliated pneumococcal strains. RrgB321 antisera mediated complement-dependent opsonophagocytosis of piliated strains at levels comparable to those achieved with the PCV7 glycoconjugate vaccine. These results suggest that a vaccine composed of RrgB321 has the potential to cover 30% or more of all pneumococcal strains and support the inclusion of this fusion protein in a multicomponent vaccine against S. pneumoniae.