Pneumococcal vaccinations effectively prevent blood culture-negative infections that resemble occult pneumococcal bacteraemia or bacteraemic pneumococcal pneumonia at one to 36 months of age

Systematic review on the impact of the pneumococcal conjugate vaccine ten valent (PCV10) or thirteen valent (PCV13) on all-cause, radiologically confirmed and severe pneumonia hospitalisation rates and pneumonia mortality in children 0-9 years old

Background

There is an ongoing need to assess the impact of pneumococcal conjugate vaccines (PCVs) to guide the use of these potentially valuable but under-utilized vaccines against pneumonia, which is one of the most common causes of post-neonatal mortality.

Methods

We conducted a systematic review of the literature on PCV10 and PCV13 impact on all-cause, radiologically confirmed and severe pneumonia hospitalisation rates as well as all-cause and pneumonia-specific mortality rates. We included studies that were published from 2003 onwards, had a post-licensure observational study design, and reported on any of our defined outcomes in children aged between 0-9 years. We derived incidence rates (IRs), incidence rate ratios (IRRs) or percent differences (%). We assessed all studies for risk of bias using the Effective Public Health Practice Project (EPHPP) quality assessment tool.

Results

We identified a total of 1885 studies and included 43 comparing one or more of the following hospitalised outcomes of interest: all-cause pneumonia (n = 27), severe pneumonia (n = 6), all-cause empyema (n = 8), radiologically confirmed pneumonia (n = 8), pneumococcal pneumonia (n = 7), and pneumonia mortality (n = 10). No studies evaluated all-cause mortality. Studies were conducted in all WHO regions except South East Asia Region (SEAR) and low- or middle-income countries (LMICs) in the Western Pacific Region (WPR). Among children <5 years old, PCV impact ranged from 7% to 60% for all-cause pneumonia hospitalisation, 8% to 90% for severe pneumonia hospitalisation, 12% to 79% for radiologically confirmed pneumonia, and 45% to 85% for pneumococcal confirmed pneumonia. For pneumonia-related mortality, impact was found in three studies and ranged from 10% to 78%. No obvious differences were found in vaccine impact between PCV10 and PCV13. One study found a 17% reduction in all-cause pneumonia among children aged 5-9 years, while another found a reduction of 81% among those aged 5-17 years. A third study found a 57% reduction in all-cause empyema among children 5-14 years of age.

Conclusion

We found clear evidence of declines in hospitalisation rates due to all-cause, severe, radiologically confirmed, and bacteraemic pneumococcal pneumonia in children aged <5 years, supporting ongoing use of PCV10 and PCV13. However, there were few studies from countries with the highest <5-year mortality and no studies from SEAR and LMICs in the WPR. Standardising methods of future PCV impact studies is recommended.

Pneumococcal vaccine effect on hospitalisation rates of pneumonia in children: A meta-analysis

INTRODUCTION

Since the appearance of the pneumococcal conjugate vaccine, the frequency of community-acquired pneumonia hospitalisations was decreased significantly especially in children below the age of 2 years, but its effects are still conflicting. This meta-analysis study was performed to assess the relationship between the effects of different types of pneumococcal conjugate vaccines compared with each other on the frequency of community-acquired pneumonia hospitalisations in children aged below 2 years.

METHODS

Through a systematic literature search up to December 2020, 20 studies were found recording relationships between the effects of different types of pneumococcal conjugate vaccines compared with each other on the frequency of community-acquired pneumonia hospitalisations in children aged below 2 years. Odds ratio (OR) with 95% confidence intervals (CIs) was calculated between different types of pneumococcal conjugate vaccines compared with each other on the frequency of community-acquired pneumonia hospitalisations in children below the age of 2 years using the dichotomous methods with a random or fixed-effect model.

RESULTS

The pneumococcal conjugate vaccine 10 was significantly related to a lower hospitalisation rate for pneumonia (OR, 0.64; 95% CI, 0.51-0.81, P < .001) compared with no vaccine and (OR, 0.78; 95% CI, 0.68-0.90, P < .001) compared with pneumococcal conjugate vaccine 7. The pneumococcal conjugate vaccine 13 was significantly related to a lower hospitalisation rate for pneumonia (OR, 0.63; 95% CI, 0.56-0.71, P < .001) compared with no vaccine and (OR, 0.56; 95% CI, 0.36-0.89, P = .01) compared with pneumococcal conjugate vaccine 7. The pneumococcal conjugate vaccine 13 was significantly related to a lower hospitalisation rate for pneumonia (OR, 0.67; 95% CI, 0.48-0.93, P = .02) compared with pneumococcal conjugate vaccine 10.

CONCLUSIONS

The pneumococcal conjugate vaccines 10 or 13 may have independent relationships in reducing the frequency of community-acquired pneumonia hospitalisations in children aged below 2 years compared with no vaccine or pneumococcal conjugate vaccines 7. Also, the pneumococcal conjugate vaccine 13 may have the same independent relationship compared with pneumococcal conjugate vaccines 10. Further studies are needed to solidify the findings to other vaccines to have evidence-based information that could help in establishing future immunisation strategies.

Deep learning for classification of pediatric chest radiographs by WHO's standardized methodology

Background

The World Health Organization (WHO)-defined radiological pneumonia is a preferred endpoint in pneumococcal vaccine efficacy and effectiveness studies in children. Automating the WHO methodology may support more widespread application of this endpoint.

Methods

We trained a deep learning model to classify pneumonia CXRs in children using the World Health Organization (WHO)’s standardized methodology. The model was pretrained on CheXpert, a dataset containing 224,316 adult CXRs, and fine-tuned on PERCH, a pediatric dataset containing 4,172 CXRs. The model was then tested on two pediatric CXR datasets released by WHO. We also compared the model’s performance to that of radiologists and pediatricians.

Results

The average area under the receiver operating characteristic curve (AUC) for primary endpoint pneumonia (PEP) across 10-fold validation of PERCH images was 0.928; average AUC after testing on WHO images was 0.977. The model’s classification performance was better on test images with high inter-observer agreement; however, the model still outperformed human assessments in AUC and precision-recall spaces on low agreement images.

Conclusion

A deep learning model can classify pneumonia CXR images in children at a performance comparable to human readers. Our method lays a strong foundation for the potential inclusion of computer-aided readings of pediatric CXRs in vaccine trials and epidemiology studies.

Effectiveness and impact of the 10-valent pneumococcal conjugate vaccine, PHiD-CV: review of clinical trials and post-marketing experience

INTRODUCTION

Pneumococcal diseases (including septicemia, meningitis, pneumonia, and upper respiratory infections) constitute a major public health problem. The World Health Organization recommends pneumococcal conjugate vaccine immunization of young children worldwide.

AREAS COVERED

We reviewed evidence on the effects of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV), which is used in childhood immunization programs in over 45 countries or regions. The effectiveness of PHiD-CV against invasive pneumococcal disease (IPD), pneumonia, and acute otitis media was assessed. We also present its effect on pneumococcal nasopharyngeal carriage (NPC) and indirect effects (herd protection) among unvaccinated individuals.

EXPERT COMMENTARY

Results from randomized, double-blind trials and post-marketing studies in various countries provide evidence of the protective efficacy, effectiveness, and impact of PHiD-CV against pneumococcal diseases. Data from different geographic locations also show reductions in NPC of vaccine pneumococcal serotypes, laying the foundation for indirect protection against pneumococcal disease. In countries where PHiD-CV is included in childhood immunization programs, there are signs of herd protection for vaccine serotypes among unvaccinated individuals. Although increases in non-vaccine serotype IPD and NPC rates were observed, there was an overall reduction of pneumococcal disease.

A pneumococcal conjugate vaccination programme reduced clinically suspected invasive disease in unvaccinated children

AIM

The 10-valent pneumococcal conjugate vaccine was introduced to the Finnish national vaccination programme for children born since June 2010. We evaluated the changes in the rates of clinically suspected invasive pneumococcal disease (IPD) in unvaccinated children to estimate the indirect herd protection impact of the programme.

METHODS

The target cohort for this ecological before and after comparison were unvaccinated children born from January 2008 to May 2010 and ineligible for the vaccination programme, who were followed up from 2011 to 2014. The reference cohort was age and season-matched children born in January 2003 to 2005 and followed up from 2006 to 2009. National data on hospital discharge codes compatible with IPD or unspecified sepsis were collected.

RESULTS

We compared the follow-up periods of 2007-2009 in the reference cohort and 2012-2014 in the target cohort. The incidence of non-laboratory-confirmed IPD in unvaccinated children fell by 68%, from 47 to 15/100 000 person-years. When unspecified sepsis was added, the decrease was 39%, from 171 to 104/100 000 person-years. Laboratory confirmed IPD fell by 44%, from 15 to 8/100 000 person-years.

CONCLUSION

The pneumococcal vaccination programme provided herd protection against clinically suspected IPD. The absolute reduction was almost 10-times higher than for just laboratory-confirmed disease.