Herd effects of child vaccination with pneumococcal conjugate vaccine against pneumococcal non-invasive community-acquired pneumonia: What is the evidence?

State of the Art and Emerging Technologies in Vaccine Design for Respiratory Pathogens

In this review, we present the efforts made so far in developing effective solutions to prevent infections caused by seven major respiratory pathogens: influenza virus, respiratory syncytial virus (RSV), the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Bordetella pertussis, Streptococcus pneumoniae (pneumococcus), Mycobacterium tuberculosis, and Pseudomonas aeruginosa. Advancements driven by the recent coronavirus disease 2019 (COVID-19) crisis have largely focused on viruses, but effective prophylactic solutions for bacterial pathogens are also needed, especially in light of the antimicrobial resistance (AMR) phenomenon. Here, we discuss various innovative key technologies that can help address this critical need, such as (a) the development of Lung-on-Chip ex vivo models to gain a better understanding of the pathogenesis process and the host-microbe interactions; (b) a more thorough investigation of the mechanisms behind mucosal immunity as the first line of defense against pathogens; (c) the identification of correlates of protection (CoPs) which, in conjunction with the Reverse Vaccinology 2.0 approach, can push a more rational and targeted design of vaccines. By focusing on these critical areas, we expect substantial progress in the development of new vaccines against respiratory bacterial pathogens, thereby enhancing global health protection in the framework of the increasingly concerning AMR emergence.

Mortality reduction with 23-valent pneumococcal polysaccharide vaccine: a systematic review and meta-analysis

BACKGROUND

Pneumococcal disease, caused by Streptococcus pneumoniae, imposes a significant global health burden, particularly affecting vulnerable groups such as the elderly and immunocompromised. The 23-valent pneumococcal polysaccharide vaccine (PPV23) is designed to protect against 23 serotypes of Streptococcus pneumoniae. However, there is ongoing debate about its effectiveness in reducing all-cause mortality. This systematic review and meta-analysis aimed to evaluate the efficacy of PPV23 in reducing all-cause and pneumonia-related mortality among adults.

METHODS

A systematic search was conducted across PubMed, Embase, and Web of Science, focusing on studies that evaluated the mortality outcomes of adults vaccinated with PPV23 compared to non-vaccinated adults. Both randomized controlled trials (RCTs) and observational studies were included, while case reports, case series, and non-human studies were excluded. Data extraction and quality assessment were facilitated by Nested Knowledge software, using the Newcastle-Ottawa Scale for observational studies and the Cochrane Risk of Bias tool for RCTs.

RESULTS

The search yielded 826 records, with 19 studies meeting the inclusion criteria. The pooled analysis of four RCTs showed no significant reduction in all-cause mortality (RR = 1.030; 95% CI: 0.945, 1.122). However, analysis of pneumonia-related mortality across various studies indicated a significant reduction (HR = 0.504; 95% CI: 0.316, 0.693). Moderate to high heterogeneity was noted in mortality studies, and a potential publication bias was identified.

CONCLUSION

The findings suggest that while PPV23 may not significantly reduce all-cause mortality, it is effective in reducing pneumonia-related mortality among adults, particularly in those at higher risk. These results support the continued use of PPV23 in targeted adult populations, emphasizing the need for more primary studies to explore its effectiveness across diverse groups.

Pneumococcal serotypes causing non-invasive pneumonia in adults from a South Indian tertiary care hospital and the impact of the newer conjugate vaccines

Background

Streptococcus pneumoniae is the leading cause of community-acquired pneumonia (CAP) in adults. Ageing, chronic conditions and comorbidities are important risk factors for pneumococcal pneumonia.

Purpose

There is lack of data on the pneumococcal serotypes causing non-invasive pneumonia in India. This study aims to determine the prevalent pneumococcal serotypes causing non-invasive pneumonia, the associated comorbidities, and the coverage of both the available pneumococcal vaccines in India and conjugate vaccines that are currently undergoing clinical trials.

Methods

A total of 280 subjects (aged >16 years) who had clinical symptoms correlating with radiological findings for non-invasive bacteremic pneumonia and microbiological evidence of S. pneumoniae between 2018 and 2020 were included. The clinical, demographic, radiological and microbiological findings were retrieved from the Hospital Information System (HIS).

Result

The common serotypes in order of prevalence were 19F, 9V, 23F, 6B, 11A, 13, 34, 10A, 19A and 6A. The predominant non-vaccine serotypes were 13, 34, 35B, 31 and 16F. The associated radiological findings were pneumonic consolidation and multi-lobar involvement. Other coinfected bacterial pathogens included H. influenzae, S. aureus, K. pneumoniae and P. aeruginosa.

Conclusion

The pneumococcal vaccines: PCV10/GSK, PCV10/SII, PCV13, PCV15, PCV20 and PPSV23 provide an overall serotype coverage of 36, 41, 47, 48, 61 and 69 %, respectively of S. pneumoniae causing non-invasive pneumonia in South India. Increasing catch-up vaccination using PCV10(SII) in pre-school children could have a more significant impact on reducing pneumococcal pneumonia in adults (>50 years) in terms of increased herd immunity at an affordable cost.

Long-term Impact of Pneumococcal Conjugate Vaccines on Invasive Disease and Pneumonia Hospitalizations in Indigenous and Non-Indigenous Australians

BACKGROUND

Universal pneumococcal conjugate vaccine (PCV) programs began in Indigenous Australian children in 2001 and all children in 2005, changing to 13-valent PCV (PCV13) in 2011. We used laboratory data for invasive pneumococcal disease (IPD) and coded hospitalizations for noninvasive pneumococcal community-acquired pneumonia (PnCAP) to evaluate long-term impact.

METHODS

Annual incidence (per 100 000 population) was calculated for age-specific total IPD, PCV13 non-7-valent PCV (PCV7) serotypes, and PnCAP by Indigenous status. Incidence in the pre-universal PCV7 (2002-2004), early PCV7 (2005-2007), pre-PCV13 (2008 to mid-2011), and post-PCV13 (mid-2011 to 2016) periods was used to calculate incidence rate ratios (IRRs).

RESULTS

In the total population, all-age incidence of IPD declined from 11.8 pre-PCV7 to 7.1 post-PCV13 (IRR, 0.61 [95% confidence interval {CI}, .59-.63]) but for PnCAP declined among ages <1 year (IRR, 0.34 [95% CI, .25-.45]) and 1-4 years (IRR, 0.50 [95% CI, .43-.57]) but increased significantly among age ≥5 years (IRRs, 1.08-1.14). In Indigenous people, baseline PCV13 non-PCV7 IPD incidence was 3-fold higher, amplified by a serotype 1 epidemic in 2011. By 2015-2016, although incidence of IPD and PnCAP in children aged <5 years decreased by 38%, neither decreased in people aged ≥5 years.

CONCLUSIONS

Fifteen years post-PCV and 5 years post-PCV13, direct and indirect impact on IPD and PnCAP differed by age and between Indigenous and non-Indigenous people, with potential implications for long-term PCV impact in comparable settings.Fifteen years after pneumococcal conjugate vaccine (PCV) introduction and 5 years post-PCV13, direct and indirect impact on invasive pneumococcal disease and pneumococcal community-acquired pneumonia differed by age and between Indigenous and non-Indigenous people, with potential implications for long-term PCV impact in comparable settings.

Community-acquired pneumonia among children: the latest evidence for an updated management

OBJECTIVE

To provide cutting-edge information for the management of community-acquired pneumonia in children under 5 years, based on the latest evidence published in the literature.

DATA SOURCE

A comprehensive search was conducted in PubMed, by using the expressions: "community-acquired pneumonia" AND "child" AND "etiology" OR "diagnosis" OR "severity" OR "antibiotic". All articles retrieved had the title and the abstract read, when the papers reporting the latest evidence on each subject were identified and downloaded for complete reading.

DATA SYNTHESIS

In the era of largely implemented bacterial conjugate vaccines and widespread use of amplification nucleic acid techniques, respiratory viruses have been identified as the most frequent causative agents of community-acquired pneumonia in patients under 5 years. Hypoxemia (oxygen saturation ≤96%) and increased work of breathing are signs most associated with community-acquired pneumonia. Wheezing detected on physical examination independently predicts viral infection and the negative predictive value (95% confidence interval) of normal chest X-ray and serum procalcitonin <0.25ng/dL was 92% (77-98%) and 93% (90-99%), respectively. Inability to drink/feed, vomiting everything, convulsions, lower chest indrawing, central cyanosis, lethargy, nasal flaring, grunting, head nodding, and oxygen saturation <90% are predictors of death and can be used as indicators for hospitalization. Moderate/large pleural effusions and multilobar infiltrates are predictors of severe disease. Orally administered amoxicillin is the first line outpatient treatment, while ampicillin, aqueous penicillin G, or amoxicillin (initiated initially by intravenous route) are the first line options to treat inpatients.

CONCLUSIONS

Distinct aspects of childhood community-acquired pneumonia have changed during the last three decades.

Commentary: Why Has Uptake of Pneumococcal Vaccines for Children Been So Slow? The Perils of Undervaluation

Pediatric pneumococcal disease exacts a substantial burden on global health, much of which is vaccine-preventable. Despite this considerable burden and the demonstrably high efficacy of pneumococcal conjugate vaccines (PCVs), the overall level of PCV uptake remains concerningly low, especially compared with that of other childhood-recommended vaccines, such as tuberculosis and polio. A broad set of plausible explanations exists for this low uptake, including logistical challenges, psychosocial factors and affordability. One additional and systematic cause of low uptake, which is the focus of our discussion, is economists' and policymakers' tendency to undervalue vaccination in general by adopting a narrow health sector perspective when performing economic evaluations of vaccines. We present an alternative, societal framework for economic evaluations that encompasses a broader set of socioeconomic benefits in addition to health benefits. Quantifying a more comprehensive taxonomy of PCV's benefits will help to address potential undervaluation and may be sufficient not only to justify recommendation and reimbursement but also to stimulate efforts and investment toward closing coverage gaps.

Vaccines to Prevent Pneumococcal Community-Acquired Pneumonia

Streptococcus pneumoniae is the most frequent pathogen in community-acquired pneumonia and also causes invasive diseases like bacteremia and meningitis. Young children and elderly are especially at risk for pneumococcal diseases and are, therefore, eligible for pneumococcal vaccination in most countries. This reviews provides an overview of the current epidemiology of pneumococcal infections, history and evidence of available pneumococcal polysaccharide and conjugate vaccines, and current recommendations.

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).