Long-term impact of pneumococcal conjugate vaccines for children on adult pneumococcal pneumonia in Japan: Two multicenter observational studies from 2011 to 2020

Hospital burden of pneumococcal disease in Spain (2016-2022): A retrospective study

Pneumococcal disease is a leading cause of morbidity and mortality worldwide. From 2016 to 2022, 358,603 hospitalized patients were identified as having pneumococcal disease. The overall annual hospitalization rate was 108.9 hospitalizations per 100,000 people, which significantly increased with age, reaching 748.0 hospitalizations per 100,000 among those aged ≥90 years. The hospitalization rates for pneumococcal pneumonia, meningitis, and sepsis were 25.4, 0.7, and 3.5 hospitalizations per 100,000 people, respectively, reaching the highest rates in those ≥90 years of age for pneumococcal pneumonia and sepsis, with 241.6 and 22.0 hospitalizations per 100,000 people, respectively, and in those <1 year of age for meningitis, with 3.4 hospitalizations per 100,000 people. The total number of deaths among all hospitalized pneumococcal infection patients was 51,668, with a total case fatality rate of 14.4%. The case fatality rates for pneumococcal pneumonia, meningitis, and sepsis were 7.9%, 10.6%, and 19.8%, respectively. The case fatality rate increased dramatically with age. Most patients presented with at least one underlying condition. The case fatality rate among patients with at least one comorbidity was significantly higher (p < .05) than that among patients without underlying conditions (16.0% vs. 3.2%, respectively), with a fivefold greater probability of death (OR = 5.7). During this period, the annual cost of hospitalizations for the health system exceeded EUR 383 million. Thus, the use of new broad-spectrum PCVs and improved vaccination protocols for elderly individuals and people with comorbidities could help reduce the high hospital burden of disease and mortality due to pneumococcal infection in our country.

Global distribution and characteristics of pneumococcal serotypes in adults

The introduction of pneumococcal conjugate vaccines (PCVs) into pediatric national immunization programs (NIP) has significantly reduced invasive pneumococcal diseases and pneumococcal pneumonia caused by PCV serotypes in adults due to herd immunity. However, diseases caused by PCV13 serotypes persist, mainly serotype 3, known for its severity. With the reduction in PCV13 serotypes, diseases caused by non-PCV13 serotypes increased. Residual and emerging serotypes vary regionally; serotype 8 in Europe and South Africa, and serotype 4 in the US and Canada. PCV20 and PCV21 were recently developed, which can prevent residual and emerging pneumococcal diseases where herd immunity is well-established. In countries that have not introduced PCV into pediatric NIP, the pneumococcal disease burden due to PCV serotypes is still marked. Given that serotype distribution varies by region and evolves over time, this review aimed to discuss serotype distribution and disease severity in adults across countries to support future pneumococcal vaccine strategies.

Health and economic impact of the 21-valent pneumococcal conjugate vaccine (V116) for adults in Japan: a delta price approach

INTRODUCTION

This study analyzed the health and economic impact of the 21-valent pneumococcal conjugate vaccine (V116) and the 20-valent pneumococcal conjugate vaccine (PCV20), as well as their relative cost-effectiveness, in Japanese adults aged 65 years using a delta pricing approach.

METHODS

A Markov model was employed to simulate the movement of the Japanese population among four health states: healthy, pneumococcal disease (consisting of invasive pneumococcal disease [IPD] with or without meningitis and non-bacteremic pneumococcal pneumonia [NBPP]), post-meningitis sequelae, and death. The model was populated with publicly available demographic and epidemiologic data, stratified by risk level. Pneumococcal serotype distribution and vaccine effectiveness, as well as direct and indirect treatment costs and health-related utilities, were derived from published sources. The model used a lifetime horizon and 2% discounting of costs and life-years. Costs were adjusted to 2023 values in Japanese yen (¥). Outcomes were cases and deaths, life-years and quality-adjusted life-years (QALYs), vaccination and treatment costs, and incremental cost-effectiveness ratios. The range over which V116 was cost-saving and cost-effective was determined.

RESULTS

Compared to PCV20, V116 averted an additional 28 cases of IPD, 918 cases of NBPP, 5 deaths from IPD, and 51 deaths from NBPP over the lifetime of a single age 65 cohort. Life-years and QALYs gained were 1,019 and 642, respectively, relative to PCV20; V116 saved ¥733 million in direct medical costs and ¥557 million in indirect costs, compared to PCV20. V116 was found to be cost-saving at price premiums up to ¥1,322 (payer perspective) or ¥2,327 (societal perspective) and remained below a willingness-to-pay threshold of ¥5 million/QALY for premiums up to ¥7,113 (payer perspective) or ¥8,117 (societal perspective).

CONCLUSIONS

V116 is projected to provide more population health benefits in Japan than PCV20, and to be cost-effective at a variety of price premiums.

Update on the evolving landscape of pneumococcal capsule types: new discoveries and way forward

SUMMARYStreptococcus pneumoniae (the "pneumococcus") is a significant human pathogen. The key determinant of pneumococcal fitness and virulence is its ability to produce a protective polysaccharide (PS) capsule, and anti-capsule antibodies mediate serotype-specific opsonophagocytic killing of bacteria. Notably, immunization with pneumococcal conjugate vaccines (PCVs) has effectively reduced the burden of disease caused by serotypes included in vaccines but has also spurred a relative upsurge in the prevalence of non-vaccine serotypes. Recent advancements in serotyping and bioinformatics surveillance tools coupled with high-resolution analytical techniques have enabled the discovery of numerous new capsule types, thereby providing a fresh perspective on the dynamic pneumococcal landscape. This review offers insights into the current pneumococcal seroepidemiology highlighting important serotype shifts in different global regions in the PCV era. It also comprehensively summarizes newly discovered serotypes from 2007 to 2024, alongside updates on revised chemical structures and the de-novo determinations of structures for previously known serotypes. Furthermore, we spotlight emerging evidence on non-pneumococcal Mitis-group strains that express capsular PS that are serologically and biochemically related to the pneumococcal capsule types. We further discuss the implications of these recent findings on capsule nomenclature, pneumococcal carriage detection, and future PCV design. The review maps out the current status and also outlines the course for future research and vaccine strategies, ensuring a continued effective response to the evolving pneumococcal challenge.

Pneumococcal vaccines for prevention of adult pneumonia

Streptococcus pneumoniae, pneumococcus, is one of most important bacterial pathogens in adult community-acquired pneumonia. Although it can cause a variety of illness including invasive diseases (IPD), pneumonia has a greater impact than IPD from the perspective of health economics. 23 valent pneumococcal polysaccharide vaccine (PPSV23) and 13 valent pneumococcal conjugate vaccine (PCV13) have been recommended for people ≥65 years old until recently based on evidence in preventing IPD and pneumonia. Because the introduction and dissemination of PCVs for infants and its effects on herd immunity have led 'serotype replacement' in adult IPD and pneumococcal pneumonia since the 2000s, serotypes targeted by vaccines have sifted accordingly. With the availability of PCV21 this year, in addition to PCV15 and PCV20, vaccine prevention strategies for adult pneumococcal pneumonia need to be reconsidered. In this narrative review, we discuss current and future challenges regarding pneumococcal vaccines to prevent adult pneumococcal pneumonia.

Strategies for pneumococcal vaccination in older adults in the coming era

Pneumonia, predominantly caused by Streptococcus pneumoniae, remains a leading cause of global mortality. The 23-valent Pneumococcal polysaccharide vaccine (PPSV23) and conjugate vaccines (PCVs) are vital measures to fight against it. This paper discussed the changes in pneumococcal vaccination strategies, particularly for older adults, as vaccine effectiveness and epidemiological patterns shift. While PPSV23 maintains effectiveness against invasive pneumococcal disease (IPD), its effectiveness against pneumococcal pneumonia is declining. Conversely, PCV13 consistently demonstrates effectiveness against both IPD and pneumonia. Consequently, the US Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices recommends using PCVs, notably PCV20 and PCV15, over PPSV23. Japanese studies indicate a change in the efficacy/effectiveness of PPSV23 following PCV introduction in children, likely owing to serotype replacement and herd immunity. Additionally, recent data reveals a plateau in the reduction of PCV13 and PPSV23-covered serotypes, posing a challenge to current strategies. This paper indicates a paradigm shift in pneumonia management, acknowledging its chronic nature and potential to exacerbate other diseases. The future of pneumococcal vaccination lies in broader serotype coverage through PCVs, adapting to serotype changes driven by childhood vaccination programs. Furthermore, continuous research and vaccine development are crucial in this evolving field.

Identification of pneumococcal serotypes with individual recognition of vaccine types by a highly multiplexed real-time PCR-based MeltArray approach

BACKGROUND

Pneumococcus serotyping is important for monitoring serotype epidemiology, vaccine-induced serotypes replacement and emerging pathogenic serotypes. However, the lack of high-resolution serotyping tools has hindered its widespread implementation.

METHODS

We devised a single-step, multiplex real-time polymerase chain reaction (PCR)-based MeltArray approach termed PneumoSero that can identify 92 serotypes with individual recognition of 54 serotypes, including all 24 currently available vaccine types. The limit of detection (LOD) and the ability to coexisting serotypes were studied, followed by analytical evaluation using 92 reference pneumococcal strains and 125 non-pneumococcal strains, and clinical evaluation using 471 pneumococcus isolates and 46 pneumococcus-positive clinical samples.

RESULTS

The LODs varied with serotypes from 50 to 100 copies per reaction and 10 % of the minor serotypes were detectable in samples containing two mixed serotypes. Analytical evaluation presented 100 % accuracy in both 92 reference pneumococcal strains and 125 non-pneumococcal strains. Clinical evaluation of 471 pneumococcus isolates displayed full concordance with Sanger sequencing results. The 46 clinical specimens yielded 45 typeable results and one untypeable result. Of the 45 typeable samples, 41 were of a single serotype and four were of mixed serotypes, all of which were confirmed by Sanger sequencing or separate PCR assays.

CONCLUSION

We conclude that the PneumoSero assay can be implemented as a routine tool for pneumococcal serotyping in standard microbiology laboratories and even in clinical settings.

Indirect protection in adults ≥18 years of age from pediatric pneumococcal vaccination: a review

INTRODUCTION

Infant immunization programs using pneumococcal conjugate vaccines (PCVs) have reduced the rates of pneumococcal disease through direct vaccine-induced protection in vaccinated children and through indirect protection in non-vaccinated children and adults.

AREAS COVERED

This review summarizes current evidence on the indirect protection of adults conferred by pediatric pneumococcal vaccination, including the impact on invasive pneumococcal disease (IPD) incidence and mortality, pneumonia admissions, and nasopharyngeal carriage prevalence. Factors affecting indirect protection against IPD are also discussed.

EXPERT OPINION

Pediatric immunization with PCVs has substantially decreased vaccine-serotype IPD and pneumonia through indirect protection in both older (≥65 years of age) and younger adults, including those with underlying medical conditions. However, serotype replacement by non-vaccine serotypes, the persistence of some vaccine serotypes, and divergence of serotypes between children and adults have limited the impact of pediatric PCV programs on adult populations. Designing complementary vaccines that leverage indirect protection from pediatric immunization and target the most prevalent adult serotypes may be a preferred strategy to maximize the public health impact of pneumococcal vaccination.

Pneumonia among under - five children in Ethiopia: a retrospective analysis from an urban hospital

Background

Pneumonia is the leading cause of death in under-five children in low-income countries. However, the burden of pneumonia in hospital admission is not traced systematically. This study was conducted to determine the proportion of under-five pneumonia admissions among children admitted to a hospital in Addis Ababa, Ethiopia between 2017-2021.

Methods

A retrospective record of pediatric admissions to the Yekatit 12 referral hospital in Addis Ababa, Ethiopia was assessed for the period 2017- 2021. The date of admission and discharge, length of stay, and outcome at discharge were collected in accordance with the Ethiopian National Classification of Diseases (NCoD). Descriptive statistics were used to assess the proportion of under-five children with pneumonia. Survival analyses using Log rank test and cox regression analysis were done to assess time to recovery (recovering from illness). Multivariable logistic regression was used to assess the influence of selected factors on pneumonia associated hospital admission.

Results

Between 2017-2021, 2170 children age 1 to 59 months were admitted, 564 (25.99%; 95% confidence interval 24.18% to 27.87%) were diagnosed with pneumonia. Among the sixty children who died during their hospitalization, 15 had been diagnosed with pneumonia. The median time to recover from pneumonia and discharge was 6 days. The odds of pneumonia hospital admission were higher among younger children (4.36 times higher compared to elder children with 95% CI 2.77,6.87)and were increased between the months of September to November.

Conclusions

Pneumonia accounts for more than a quarter of hospital admissions in under-five children and for a quarter of deaths in this urban cohort. Hospital admission due to pneumonia was higher among older children (36-59 months of age) in the months following the heavy rain months (September to November) as compared to younger children. Our data strongly support increase of vaccination to prevent under 5 pneumonia.

Safety and immunogenicity of sequential administration of PCV13 followed by PPSV23 in pneumococcal vaccine-naïve adults aged ≥ 65 years: Comparison of booster effects based on intervals of 0.5 and 1.0 year

OBJECTIVE

An open-label study was conducted to compare the safety and immunogenicity of a sequential administration of 13-valent pneumococcal conjugate vaccine (PCV13) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) between an interval of 0.5 (0.5-y) and 1 year (1.0-y) in adults aged ≥ 65 years.

METHODS

Pneumococcal vaccine-naïve adults aged ≥ 65 years (n = 129) received a sequential administration with an interval of 0.5-y or 1.0-y or received a single administration of PPSV23 (single PPSV23). We evaluated the immunogenicity before and 1 month after each vaccination and at 0.5-y intervals for 2 years. The primary endpoint was the increase in geometric mean fold rises (GMFRs) of immunoglobulin G (IgG) or opsonophagocytic activity (OPA) for eight common serotypes one month after one dose of PPSV23. The secondary endpoint was the safety profile for one dose of PPSV23.

RESULTS

One month after administration of PPSV23, the GMFRs of IgG considerably increased for five of eight serotypes in the 1.0-y interval group, whereas the GMFRs of IgG considerably increased for two serotypes in the 0.5-y interval group. Furthermore, GMFRs of OPA markedly increased for all eight serotypes in the 1.0-y interval group, while GMFRs of OPA markedly increased for four serotypes in the 0.5-y interval group. At 2 years after initial vaccination, GMFRs of IgG or OPA were higher for all serotypes, except for serotype 3, than those in the single PPSV23 group irrespective of intervals. No significant difference was found in the frequencies of local reactions of all grades between the two intervals.

CONCLUSIONS

The 1.0-y interval provided better booster effects induced by PPSV23 than those of the 0.5-y interval in a sequential administration in pneumococcal vaccine-naïve adults aged ≥ 65 years. No difference was found in the safety profile between both intervals.

Burden of Hospitalizations Related to Pneumococcal Infection in Spain (2016-2020)

Pneumococcal infection strongly contributes to morbidity and mortality in Spain. A total of 253,899 hospitalizations related to pneumococcal infection occurred from 2016 to 2020. Fifty-eight percent were men, the mean age was 67 years old, and the average length of hospitalization was 12.72 days. The annual hospitalization rate was 10.84 hospitalizations per 10,000 population, increasing significantly with age, reaching 65.75 per 10,000 population in those aged >85 years. The hospitalization rates for pneumococcal pneumonia, sepsis, and meningitis were 2.91, 0.12, and 0.08 hospitalizations per 10,000, respectively, and reached the highest value in those aged >85 for pneumococcal pneumonia and sepsis, with 22.29 and 0.71 hospitalizations per 10,000, respectively, and in children up to 1 year old for pneumococcal meningitis, with 0.33 hospitalizations per 10,000. The total number of deaths during the study period was 35,716, with a case-fatality rate of 14.07%. For pneumococcal pneumonia, sepsis, and meningitis, the case-fatality rates were 8.47%, 23.71%, and 9.99%, respectively. The case-fatality rate increased with age and did not vary by sex. The annual cost of these hospitalizations was more than EUR 359 million. There is therefore a high burden of disease and mortality caused by pneumococcal infection in our country, especially in elderly individuals.