Surveillance of the impact of pneumococcal conjugate vaccines in developing countries

Potential Impact of Higher-Valency Pneumococcal Conjugate Vaccines Among Adults in Different Localities in Germany

Next-generation pneumococcal conjugate vaccines (PCVs) have been approved for use. The serotype distribution of pneumococcal isolates can vary between regions. To understand the potential impacts of new PCVs, we evaluated trends in invasive pneumococcal disease (IPD) among adults in Germany at a local level using Bayesian hierarchical logistic regression. There was little spatial variation in IPD cases caused by 13-valent PCV serotypes, which dropped from 60% of IPD cases in 2006 to 30% in 2018. More than half of IPD cases in 2018 were attributable to serotypes covered by new PCVs (15-valent and 20-valent PCVs), which suggests they could further reduce the burden of IPD.

Pneumonia Mortality Trends in Children under 5 Years of Age in the Context of Pneumococcal Conjugate Vaccination in Peru, 2003-2017

Worldwide, conjugated pneumococcal vaccines (PCVs) have proven effective against invasive pneumococcal disease, but non-invasive pneumonia is a major cause of mortality in young children and serotypes vary geographically, affecting effectiveness. We analyze nationwide death certificate data between 2003-2017 to assess the impact of PCVs on pneumonia mortality among young children from Peru. We report descriptive statistics and perform timeseries analysis on annual mortality rates (AMRs) and monthly frequencies of pneumonia deaths. Children under 5 years of age accounted for 6.2% (n = 10,408) of all pneumonia deaths (N = 166,844), and 32.3% (n = 3363) were children between 1-4 years of age, of which 95.1% did not report pneumonia etiology. Comparing periods before and after PCV introduction in 2009, mean AMRs dropped 13.5% and 26.0% for children between 1-4 years of age (toddlers/preschoolers), and children under 1 year of age (infants), respectively. A moderate correlation (Spearman's r = 0.546, p < 0.01) in the monthly frequency of pneumonia deaths was estimated between both age groups. Quadratic regression suggests a change in direction around 2005 (highest pneumonia mortality) for both age groups, but percentage change analysis identified an inflection point in 2013 for infants only, not for toddlers/preschoolers, suggesting that the impact of PCVs might be different for each age group.

A brief history of and future prospects for pneumococcal vaccination in Malaysia

Pneumococcal pneumonia remains a significant global public health issue. Malaysia has recently added the 10 valent pneumococcal conjugate vaccine to its national immunisation programme. Data on pneumococcal serotype epidemiology is vital for informing national vaccination policy. However, there remains a lack of representative population-based pneumococcal surveillance in Malaysia to help both the assessment of vaccine effectiveness in the country and to shape future vaccine policy. This review explores the history of pneumococcal vaccination, the burden of pneumococcal disease in Malaysia, and offers an insight into the prospects for reducing pneumococcal disease in Malaysia.

Infant mortality rates and pneumococcal vaccines: a time-series trend analysis in 194 countries, 1950-2020

Pneumonia due to Streptococcus pneumoniae (pneumococcus) is a major cause of mortality in infants (children under 1 year of age), and pneumococcal conjugate vaccines (PCVs), delivered during the first year of life, are available since the year 2000. Given those two premises, the conclusion follows logically that favourable impact reported for PCVs in preventing pneumococcal disease should be reflected in the infant mortality rates (IMRs) from all causes. Using publicly available datasets, country-level IMR estimates from UNICEF and PCV introduction status from WHO, country-specific time series analysed the temporal relationship between annual IMRs and the introduction of PCVs, providing a unique context into the long-term secular trends of IMRs in countries that included and countries that did not include PCVs in their national immunisation programmes. PCV status was available for 194 countries during the period 1950-2020: 150 (77.3%) of these countries achieved nationwide PCV coverage at some point after the year 2000, 13 (6.7%) achieved only partial or temporary PCV coverage, and 31 (15.9%) never introduced PCVs to their population. One hundred and thirty-nine (92.7%) of countries that reported a decreasing (negative) trend in IMR, also reported a strong correlation with decreasing maternal mortality rates (MMRs), suggesting an improvement in overall child/mother healthcare. Conversely, all but one of the countries that never introduced PCVs in their national immunisation programme also reported a decreasing trend in IMR that strongly correlates with MMRs. IMRs have been decreasing for decades all over the world, but this latest decrease may not be related to PCVs.

Herd immunity in older adults from a middle-income country: A time-series trend analysis of community-acquired pneumonia mortality 2003-2017

Background and Aims

Community-acquired pneumonia is responsible for substantial mortality, and pneumococcus is commonly accepted as a major cause of pneumonia, regardless of laboratory confirmation. Child immunization programs have reported success in decreasing pneumonia mortality: directly in young children and indirectly (herd immunity) in unvaccinated adult populations in some countries. We assess changes in mortality trends for all-cause pneumonia in older adults associated with the introduction of pneumococcal vaccination for children in Peru.

Methods

This is a secondary analysis on administrative data collected periodically by the Peruvian Ministry of Health. An observational retrospective time series analysis was conducted using longitudinal population-based data from death certificates in Peru between 2003 and 2017. The time series includes 6 years before and 9 years after the introduction of the pneumococcal-conjugated vaccines in the national child immunization program in 2009. Monthly frequencies and annual rates for all-cause pneumonia deaths in children under 5 years of age and adults over 65 years of age are presented. Linear and quadratic trends are analyzed.

Results

Deaths among older adults accounted for 75.6% of all-cause pneumonia mortality in Peru, with 94.4% of these reporting "pneumonia due to unspecified organism" as the underlying cause of death. Comparing pre- and post-child immunization program periods, annual average mortality rates from unspecified pneumonia decreased by 22.7% in young children but increased by 19.6% in older adults. A linear trend model supports this overall tendency, but a quadratic curve explains the data better.

Conclusion

Pneumococcal-conjugated vaccines are developed using serotypes prevalent in selected countries from less common (invasive) pneumococcal disease and expected to prevent mortality worldwide from widespread (noninvasive) pneumonia. Our results do not support the presence of herd immunity from pneumococcal vaccination of children for community-acquired pneumonia in the increasingly ageing population of Peru. This should direct future research and could influence public health policy.

30-Minute Highly Multiplexed VaxArray Immunoassay for Pneumococcal Vaccine Antigen Characterization

Pneumonia accounts for over 20% of deaths worldwide in children aged 1 to 5 years, disproportionately affecting lower- and middle-income countries. Effective, highly multivalent pneumococcal vaccines are available to decrease disease burden, with numerous new vaccines currently under development to serve a variety of worldwide markets. However, pneumococcal conjugate vaccines are among the hardest biologics to manufacture and characterize due to their complexity and heterogeneity. Current characterization methods are often inherently singleplex, requiring separate tests for each serotype present. In addition, identity and quantity are often determined with separate methods. We developed the VaxArray pneumococcal assay for applications in identity, quantity, and stability testing of pneumococcal polysaccharide and pneumococcal conjugate vaccines. The VaxArray pneumococcal assay has a time to result of less than 30 min and is an off-the-shelf multiplexed, microarray-based immunoassay kit that can identify and simultaneously quantify 23 pneumococcal polysaccharide serotypes common to many on-market and in-development vaccines. Here, we highlight the potential of the assay for identity testing by showing high reactivity and serotype specificity to a wide variety of native polysaccharides, CRM197-conjugated polysaccharides, and drug product. The assay also has vaccine-relevant lower limits of quantification in the low-to-mid ng/mL range and can be used for accurate quantification even in adjuvanted vaccines. Excellent correlation to the anthrone assay is demonstrated, with VaxArray resulting in significantly improved precision over this antiquated chemical method.

Pneumococcal Immunization Strategies for High-Risk Pediatric Populations Worldwide: One Size Does Not Fit All

Despite the significant reduction in pneumococcal disease due to pneumococcal vaccines, protection of vulnerable high-risk individuals, especially pediatric populations, remains a great challenge. In an effort to maximize the protection of high-risk children against pneumococcal disease, a combined schedule that includes both conjugate and polysaccharide vaccines is recommended by several countries in the developed world. On the other hand, middle- and low-income countries do not have in place established policies for pneumococcal immunization of children at risk. Pneumococcal conjugate vaccines, despite their benefits, have several limitations, mainly associated with serotype replacement and the wide range of serotype coverage worldwide. In addition, PPV23-impaired immunogenicity and the hyporesponsiveness effect among populations at risk have been well-documented. Therefore, the added value of continuing to include PPV23 in vaccination schedules for high-risk individuals in the years to come remains to be determined by monitoring whether the replacing/remaining serotypes causing IPD are covered by PPV23 to determine whether its benefits outweigh its limitations. In this review, we aim to describe serotype distribution and vaccine efficacy data on pneumococcal disease in the pre- and post-PCV implementation era among high-risk children in both developed and developing countries, assessing the optimization of current recommendations for their vaccination against pneumococcal disease.

Pneumococcal Carriage Among Indigenous Kichwa Children From the Ecuadorian Andes After the 10-Valent Pneumococcal Vaccine Introduction

BACKGROUND

We assessed nasopharyngeal pneumococcal carriage in Andean Kichwa children, the largest Amerindian indigenous population in the Ecuadorian Andes. All children in our study had been vaccinated with the 10-valent pneumococcal vaccine (PCV10).

METHODS

Nasopharyngeal swabs from 63 families, 100 children <10 years old including 38 children under 5 years and 63 adult caregivers, from 5 different communities, were cultivated for Streptococcus pneumoniae and isolates were serotyped and antibiotic susceptibility testing was performed.

RESULTS

Respectively, 67% of the 38 children under 5 years old, 49% of the 62 children between 6 and 10 years old and 16% of the 100 adults were colonized with S. pneumoniae. Of these, 30.9% carried a vaccine serotype, 5.4% a serotype shared by the PCV10/13-valent pneumococcal vaccine (PCV13) vaccine and 25.5% a PCV13 serotype or PCV13 vaccine-related serotype, with 19A (10.9%) and 6C (10.9%) as the most prominent. Drug susceptibility testing revealed that 46% of the S. pneumoniae strains were susceptible to 6 tested antibiotics. However, 20.3% of the strains were multidrug-resistant or extensively drug-resistant strains, including 82% of the vaccine (-related) serotype 19A and 6C strains.

CONCLUSIONS

Kichwa children, vaccinated with PCV10, were highly colonized with pneumococci and should be considered a high-risk group for pneumococcal disease. Twenty-five percent of the colonizing S. pneumoniae strains were PCV13-only vaccine-targeted serotypes, and in addition to that, most were multidrug-resistant or extensively drug-resistant strains. The vaccine benefits for this population possibly will significantly increase with the introduction of PCV13.

Clinical and Economic Burden of Pneumococcal Disease Due to Serotypes Contained in Current and Investigational Pneumococcal Conjugate Vaccines in Children Under Five Years of Age

INTRODUCTION

The widespread implementation of pneumococcal conjugate vaccines (PCVs) has significantly reduced the burden of pneumococcal disease around the world. Although licensed 10-valent (PCV10) and 13-valent (PCV13) vaccines have considerably reduced mortality and morbidity, a sizeable disease burden attributable to serotypes not contained in these PCVs remains. This study aimed to estimate the annual clinical and economic burden of pneumococcal disease attributable to licensed (PCV10 and PCV13) and investigational PCVs, notably 15-valent (PCV15) and 20-valent (PCV20) vaccines, in 13 countries in children under 5 years of age.

METHODS

A decision-analytic model was created to aggregate total cases [inclusive of invasive pneumococcal disease (IPD), pneumonia, and otitis media (OM)], deaths, and direct costs in each country of interest [stratified by PCV10/PCV13 countries, depending on national immunization programs (NIPs)] over 1 year, using up to the three most recent years of available serotype coverage data. Data inputs were sourced from local databases, surveillance reports, and published literature.

RESULTS

In 5 PCV10 NIPs (Austria, Finland, Netherlands, New Zealand, Sweden), most remaining PCV20-type disease was due to PCV13-unique serotypes (30-85%), followed by PCV20-unique (9-50%), PCV15-unique (4-15%), and PCV10-unique (2-14%) serotypes. In 8 PCV13 NIPs (Australia, Canada, France, Germany, Italy, South Korea, Spain, United Kingdom), most remaining PCV20-type disease was caused by PCV20-unique serotypes (16-69%), followed by PCV13-unique (11-54%), PCV15-unique (2-33%), and PCV10-unique serotypes (3-19%). Across all countries, PCV20 serotypes caused 3000 to 345,000 cases of disease and cost between $1.3 and $44.9 million USD annually with variability driven by population size, NIP status, and epidemiologic inputs. In aggregate, PCV20 serotypes caused 1,234,000 cases and $213.5 million in annual direct medical costs in children under 5 years of age.

CONCLUSION

Despite the success of PCV10 and PCV13 in reducing pneumococcal disease, a substantial clinical and economic burden remains due to serotypes contained in investigational vaccines.

Nasopharyngeal pneumococcal carriage in South Asian infants: Results of observational cohort studies in vaccinated and unvaccinated populations

Background

Nasopharyngeal pneumococcal carriage (NPC) is a prerequisite for invasive pneumococcal disease and reduced carriage of vaccine serotypes is a marker for the protection offered by the pneumococcal conjugate vaccine (PCV). The present study reports NPC during the first year of life in a vaccinated (with PCV10) cohort in Bangladesh and an unvaccinated cohort in India.

Methods

A total of 450 and 459 infants were recruited from India and Bangladesh respectively within 0-7 days after birth. Nasopharyngeal swabs were collected at baseline, 18 and 36 weeks after birth. The swabs were processed for pneumococcal culture and identification of serotypes by the Quellung test and polymerase chain reaction (PCR). An identical protocol was applied at both sites.

Results

Prevalence of NPC was 48% in the Indian and 54.8% in the Bangladeshi cohort at 18 weeks. It increased to 53% and 64.8% respectively at 36 weeks. The average prevalence of vaccine serotypes was higher in the Indian cohort (17.8% vs 9.8% for PCV-10 and 26.1% vs17.6% for PCV-13) with 6A, 6B, 19F, 23F, and 19A as the common serotypes. On the other hand, the prevalence of non-vaccine serotypes was higher (43.6% vs 27.1% for non-PCV13) in the Bangladeshi cohort with 34, 15B, 17F, and 35B as the common serotypes. Overcrowding was associated with increased risk of pneumococcal carriage. The present PCV-13 vaccine would cover 28%-30% and 47%-48% serotypes in the Bangladeshi and Indian cohorts respectively.

Conclusions

South Asian infants get colonised with pneumococci early in infancy; predominantly vaccine serotypes in PCV naïve population (India) and non-vaccine serotypes in the vaccinated population (Bangladesh). These local findings are important to inform the public health policy and the development of higher valent pneumococcal vaccines.

The Role of Molecular Testing in Pediatric Meningitis Surveillance in Southern and East African Countries, 2008-2017

Background

As part of the global Invasive Bacterial Vaccine-Preventable Diseases Surveillance Network, 12 African countries referred cerebrospinal fluid (CSF) samples to South Africa’s regional reference laboratory. We evaluated the utility of real-time polymerase chain reaction (PCR) in detecting and serotyping/grouping Haemophilus influenzae, Neisseria meningitidis, and Streptococcus pneumoniae (HNS).

Methods

From 2008 to 2017, CSF samples collected from children <5 years old with suspected meningitis underwent routine microbiology testing in-country, and 11 680 samples were submitted for HNS PCR at the regional reference laboratory. Unconditional logistic regression, with adjustment for geographic location, was performed to identify factors associated with PCR positivity.

Results

The overall HNS PCR positivity rate for all countries was 10% (1195 of 11 626 samples). In samples with both PCR and culture results, HNS PCR positivity was 11% (744 of 6747 samples), and HNS culture positivity was 3% (207 of 6747). Molecular serotype/serogroup was assigned in 75% of PCR-positive specimens (762 of 1016). Compared with PCR-negative CSF samples, PCR-positive samples were more often turbid (adjusted odds ratio, 6.80; 95% confidence interval, 5.67–8.17) and xanthochromic (1.72; 1.29–2.28), had elevated white blood cell counts (6.13; 4.71–7.99) and high protein concentrations (5.80; 4.34–7.75), and were more often HNS culture positive (32.70; 23.18–46.12).

Conclusion

PCR increased detection of vaccine-preventable bacterial meningitis in countries where confirmation of suspected meningitis cases is impeded by limited culture capacity.

Estimating the Public Health and Economic Impact of Introducing the 13-Valent Pneumococcal Conjugate Vaccine or 10-Valent Pneumococcal Conjugate Vaccines into State Immunization Programs in India

Introduction

Although the pneumococcal conjugate vaccine (PCV) has been introduced into select state immunization programs (SIPs) in India, many children remain unvaccinated. Recently, India’s Advisory Committee on Vaccines & Immunization Practices recommended PCV on the pediatric immunization schedule nationally. This study estimates the public health and economic impact of introducing either Pfizer’s 13-valent PCV (PCV13-PFE), GlaxoSmithKline’s 10-valent PCV (PCV10-GSK), or Serum Institute of India’s 10-valent PCV (PCV10-SII) into every pediatric SIP.

Methods

A model was developed to predict the disease cases, deaths, and costs associated with implementing PCV13-PFE, PCV10-GSK, or PCV10-SII in SIPs compared to no vaccination program across a 5-year period (2021–2025). State and national-level uptake rate and clinical and economic input parameters were collected from published literature. Disease outcomes included invasive pneumococcal disease, inpatient and outpatient pneumonia, and otitis media. Costs were estimated as vaccine-related costs and direct medical costs incurred to the healthcare system. Results were reported by individual state and aggregated nationally.

Results

Estimated over 5 years, implementing PCV13-PFE in SIPs could avert 12.1 million cases and save 626,512 lives among children under 5 years old compared to no vaccination. This corresponds to net national cost savings of over $1.0 billion. Both lower-valent PCVs are estimated to provide less economic savings than PCV13-PFE inclusive of vaccine-related costs. Compared with PCV13-PFE, implementing PCV10-GSK or PCV10-SII nationally is estimated to have a smaller public health impact, with PCV10-GSK averting 8.4 million cases (436,577 deaths) and PCV10-SII preventing 10.3 million cases (531,545 deaths) in India compared to no vaccination, respectively.

Conclusion

Implementation of PCV13-PFE throughout India is estimated to provide greater public health and economic benefits than PCV10-GSK or PCV10-SII SIPs. Our analysis highlights the substantial disease cases, deaths, and health system cost savings that may be realized from implementing PCV programs throughout India.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00498-4.

Decreased number of hospitalized children with severe acute lower respiratory infection after introduction of the pneumococcal conjugate vaccine in the Eastern Democratic Republic of the Congo

Introduction

acute lower respiratory infections (ALRI) are a leading killer of children under five worldwide including the Democratic Republic of the Congo (DR Congo). We aimed to determine the morbidity and case fatality rate due to ALRI before and after introduction of the 13-valent pneumococcal conjugate vaccine (PVC13) in DR Congo 2013.

Methods

data were collected from medical records of children with a diagnosis of ALRI, aged from 2 to 59 months, treated at four hospitals in the Eastern DR Congo. Two study periods were defined; from 2010 to 2012 (before introduction of PCV13) and from 2014 to 2015 (after PCV13 introduction).

Results

out of 21,478 children admitted to the hospitals during 2010-2015, 2,007 were treated for ALRI. The case fatality rate among these children was 4.9%. Death was significantly and independently associated with malnutrition, severe ALRI, congenital disease and symptoms of fatigue. Among the ALRI hospitalised children severe ALRI decreased from 31% per year to 18% per year after vaccine introduction (p = 0.0002) while the fatality rate remained unchanged between the two study periods. Following introduction of PCV13, 63% of the children diagnosed with ALRI were treated with ampicillin combined with gentamicin while 33% received ceftriaxone and gentamicin.

Conclusion

three years after PCV13 introduction in the Eastern part of the DR Congo, we found a reduced risk of severe ALRI among children below five years. Broad-spectrum antibiotics were frequently used for the treatment of ALRI in the absence of any microbiological diagnostic support.

Anti-capsular immunity to Streptococcus pneumoniae serotype 22F prevents bacterial transmission in murine colonization and influenza virus co-infection models

We evaluated the effectiveness of anti-22F serotype immunity in the prevention of Streptococcus pneumoniae (Spn) bacterial transmission during colonization and influenza virus co-infection. Mice were immunized with 22F formulation and later colonized with Spn or co-infected with Spn and influenza virus. The 22F antisera exhibited strong reactivity to 22F bacteria and promoted the opsonic uptake of Spn by the neutrophils. The 22F vaccination led to a significant reduction of bacterial densities in the nasopharynx and prevented bacterial transmission during colonization and co-infection. The transfer of 22F antisera to infant mice resulted in reduced bacterial transmission in colonization and co-infection models.

Etiology of Pediatric Bacterial Meningitis Pre- and Post-PCV13 Introduction Among Children Under 5 Years Old in Lomé, Togo

Background

Pediatric bacterial meningitis (PBM) causes severe morbidity and mortality within Togo. Thus, as a member of the World Health Organization coordinated Invasive Bacterial Vaccine Preventable Diseases network, Togo conducts surveillance targeting Streptococcus pneumoniae (pneumococcus), Neisseria meningitidis (meningococcus), and Haemophilus influenzae, at a sentinel hospital within the capital city, Lomé, in the southernmost Maritime region.

Methods

Cerebrospinal fluid was collected from children <5 years with suspected PBM admitted to the Sylvanus Olympio Teaching Hospital. Phenotypic detection of pneumococcus, meningococcus, and H. influenzae was confirmed through microbiological techniques. Samples were shipped to the Regional Reference Laboratory to corroborate results by species-specific polymerase chain reaction.

Results

Overall, 3644 suspected PBM cases were reported, and 98 cases (2.7%: 98/3644) were confirmed bacterial meningitis. Pneumococcus was responsible for most infections (67.3%: 66/98), followed by H. influenzae (23.5%: 23/98) and meningococcus (9.2%: 9/98). The number of pneumococcal meningitis cases decreased by 88.1% (52/59) postvaccine introduction with 59 cases from July 2010 to June 2014 and 7 cases from July 2014 to June 2016. However, 5 cases caused by nonvaccine serotypes were observed. Fewer PBM cases caused by vaccine serotypes were observed in infants <1 year compared to children 2–5 years.

Conclusions

Routine surveillance showed that PCV13 vaccination is effective in preventing pneumococcal meningitis among children <5 years of age in the Maritime region. This complements the MenAfriVac vaccination against meningococcal serogroup A to prevent meningitis outbreaks in the northern region of Togo. Continued surveillance is vital for estimating the prevalence of PBM, determining vaccine impact, and anticipating epidemics in Togo.

Impact of 13-Valent Pneumococcal Conjugate Vaccine on Colonization and Invasive Disease in Cambodian Children

BACKGROUND

Cambodia introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in January 2015 using a 3 + 0 dosing schedule and no catch-up campaign. We investigated the effects of this introduction on pneumococcal colonization and invasive disease in children aged <5 years.

METHODS

There were 6 colonization surveys done between January 2014 and January 2018 in children attending the outpatient department of a nongovernmental pediatric hospital in Siem Reap. Nasopharyngeal swabs were analyzed by phenotypic and genotypic methods to detect pneumococcal serotypes and antimicrobial resistance. Invasive pneumococcal disease (IPD) data for January 2012-December 2018 were retrieved from hospital databases. Pre-PCV IPD data and pre-/post-PCV colonization data were modelled to estimate vaccine effectiveness (VE).

RESULTS

Comparing 2014 with 2016-2018, and using adjusted prevalence ratios, VE estimates for colonization were 16.6% (95% confidence interval [CI] 10.6-21.8) for all pneumococci and 39.2% (95% CI 26.7-46.1) for vaccine serotype (VT) pneumococci. There was a 26.0% (95% CI 17.7-33.0) decrease in multidrug-resistant pneumococcal colonization. The IPD incidence was estimated to have declined by 26.4% (95% CI 14.4-35.8) by 2018, with a decrease of 36.3% (95% CI 23.8-46.9) for VT IPD and an increase of 101.4% (95% CI 62.0-145.4) for non-VT IPD.

CONCLUSIONS

Following PCV13 introduction into the Cambodian immunization schedule, there have been declines in VT pneumococcal colonization and disease in children aged <5 years. Modelling of dominant serotype colonization data produced plausible VE estimates.

Streptococcus pneumoniae Nasopharyngeal Carriage among PCV-10-Vaccinated HIV-1-Infected Children with Maintained Serological Memory in Ethiopia

Streptococcus pneumoniae (S. pneumoniae) vaccines have substantially reduced the burden of invasive pneumococcal diseases (IPDs) worldwide. Despite high coverage with S. pneumoniae vaccination, upper-respiratory-tract colonization by S. pneumoniae is still common. We assessed maintenance of serological responses to S. pneumoniae serotypes included in PCV-10 by ELISA in HIV-1-infected children (n = 50) and age-matched controls (n = 50) in Ethiopia. We isolated S. pneumoniae in nasopharyngeal swabs and determined S. pneumoniae serotype by whole genome sequencing (WGS). Comparable levels of S. pneumoniae serotype-specific IgG concentrations were detected in plasma of HIV-1-infected children and matched controls, with geometric mean concentrations (GMCs) consistently higher than the protective threshold for PCV-10 serotypes of 0.35 μg/mL. We isolated S. pneumoniae from 38 (out of 97) nasopharyngeal swabs, 25 from HIV-1-infected children and 13 from controls. WGS based serotyping revealed 22 known S. pneumoniae serotypes and 2 nontypeable (NT) isolates. Non-PCV-10 serotypes represented >90% of isolates. We showed that HIV-1-infected children and matched controls in Ethiopia carry a level of maintained serological memory to PCV-10 considered protective for IPDs. We identified a higher proportion of nasopharyngeal carriage with highly pathogenic S. pneumoniae non-PCV strains among HIV-1-infected children compared to controls.

Challenges in the diagnosis of paediatric pneumonia in intervention field trials: recommendations from a pneumonia field trial working group

Pneumonia is a leading killer of children younger than 5 years despite high vaccination coverage, improved nutrition, and widespread implementation of the Integrated Management of Childhood Illnesses algorithm. Assessing the effect of interventions on childhood pneumonia is challenging because the choice of case definition and surveillance approach can affect the identification of pneumonia substantially. In anticipation of an intervention trial aimed to reduce childhood pneumonia by lowering household air pollution, we created a working group to provide recommendations regarding study design and implementation. We suggest to, first, select a standard case definition that combines acute (≤14 days) respiratory symptoms and signs and general danger signs with ancillary tests (such as chest imaging and pulse oximetry) to improve pneumonia identification; second, to prioritise active hospital-based pneumonia surveillance over passive case finding or home-based surveillance to reduce the risk of non-differential misclassification of pneumonia and, as a result, a reduced effect size in a randomised trial; and, lastly, to consider longitudinal follow-up of children younger than 1 year, as this age group has the highest incidence of severe pneumonia.

Pneumococcal conjugate vaccine rollout in India: Expectations and challenges

India is one among the four Asian countries with the greatest number of deaths due to pneumococcal infection among children under 5 years. pneumococcal conjugate vaccine (PCV) has been introduced in a phased manner in five major Indian states. Ambiguity remains in choosing the appropriate type of PCV and optimum schedule with maximum effectiveness specific for each country. Here, we discuss the evidences with respect to serotype coverage, immunogenicity, reactogenicity and dosage schedule for introduction of PCV13 in India. In addition, the expected PCV impact and the challenges are detailed. PCV13 is expected to provide >75% serotype coverage for invasive pneumococcal disease (IPD) serotypes in Indian children combined with the replacement by nonvaccine serotypes which is unpredictable due to lack of complete data. Nasopharyngeal (NP) surveillance is easy, feasible and can replace IPD surveillance in resource-poor settings. Continuous IPD as well as NP surveillance in all the regions are necessary to assess the impact of PCV in India.

Evaluation of a phased pneumococcal conjugate vaccine introduction in Mongolia using enhanced pneumonia surveillance and community carriage surveys: a study protocol for a prospective observational study and lessons learned

Background

Streptococcus pneumoniae causes substantial morbidity and mortality among children. The introduction of pneumococcal conjugate vaccines (PCV) has the potential to dramatically reduce disease burden. As with any vaccine, it is important to evaluate PCV impact, to help guide decision-making and resource-allocation. Measuring PCV impact can be complex, particularly to measure impact on one of the most common and significant diseases caused by the pneumococcus, namely pneumonia. Here we outline the protocol developed to evaluate the impact of 13-valent PCV (PCV13) on childhood pneumonia in Mongolia, and a number of lessons learned in implementing the evaluation that may be helpful to other countries seeking to undertake pneumonia surveillance.

Methods

From 2016 PCV13 was introduced in a phased manner into the routine immunisation programme with some catch-up by the Government of Mongolia. We designed an evaluation to measure vaccine impact in children aged 2–59 months with hospitalised radiological pneumonia as a primary outcome, with secondary objectives to measure impact on clinically-defined pneumonia, nasopharyngeal carriage of S. pneumoniae among pneumonia patients and in the community, and severe respiratory infection associated with RSV and/or influenza. We enhanced an existing hospital-based pneumonia surveillance system by incorporating additional study components (nasopharyngeal swabbing using standard methods, C-reactive protein, risk factor assessment) and strengthening clinical practices, such as radiology as well as monitoring and training. We conducted cross-sectional community carriage surveys to provide data on impact on carriage among healthy children.

Discussion

Establishing a robust surveillance system is an important component of monitoring the impact of PCV within a country. The enhanced surveillance system in Mongolia will facilitate assessment of PCV13 impact on pneumonia, with radiological confirmed disease as the primary outcome. Key lessons arising from this evaluation have included the importance of establishing a core group of in-country staff to be responsible for surveillance activities and to work closely with this team; to be aware of external factors that could potentially influence disease burden estimates; to be flexible in data collection processes to respond to changing circumstances and lastly to ensure a consistent application of the pneumonia surveillance case definition throughout the study period.

Novel Protein-Based Pneumococcal Vaccines: Assessing the Use of Distinct Protein Fragments Instead of Full-Length Proteins as Vaccine Antigens

Non-serotype-specific protein-based pneumococcal vaccines have received extensive research focus due to the limitations of polysaccharide-based vaccines. Pneumococcal proteins (PnPs), universally expressed among serotypes, may induce broader immune responses, stimulating humoral and cellular immunity, while being easier to manufacture and less expensive. Such an approach has raised issues mainly associated with sequence/level of expression variability, chemical instability, as well as possible undesirable reactogenicity and autoimmune properties. A step forward employs the identification of highly-conserved antigenic regions within PnPs with the potential to retain the benefits of protein antigens. Besides, their low-cost and stable construction facilitates the combination of several antigenic regions or peptides that may impair different stages of pneumococcal disease offering even wider serotype coverage and more efficient protection. This review discusses the up-to-date progress on PnPs that are currently under clinical evaluation and the challenges for their licensure. Focus is given on the progress on the identification of antigenic regions/peptides within PnPs and their evaluation as vaccine candidates, accessing their potential to overcome the issues associated with full-length protein antigens. Particular mention is given of the use of newer delivery system technologies including conjugation to Toll-like receptors (TLRs) and reformulation into nanoparticles to enhance the poor immunogenicity of such antigens.

Effect of ten-valent pneumococcal conjugate vaccine introduction on pneumococcal carriage in Fiji: results from four annual cross-sectional carriage surveys

BACKGROUND

The indirect effects of pneumococcal conjugate vaccines (PCVs) are mediated through reductions in carriage of vaccine serotypes. Data on PCVs in Asia and the Pacific are scarce. Fiji introduced the ten-valent PCV (PCV10) in 2012, with a schedule consisting of three priming doses at 6, 10, and 14 weeks of age and no booster dose (3 + 0 schedule) without catch-up. We investigated the effects of PCV10 introduction using cross-sectional nasopharyngeal carriage surveys.

METHODS

We did four annual carriage surveys (one pre-PCV10 and three post-PCV10) in the greater Suva area in Fiji, during 2012-15, of 5-8-week-old infants, 12-23-month-old children, 2-6-year-old children, and their caregivers (total of 8109 participants). Eligible participants were of appropriate age, had axillary temperature lower than 37°C, and had lived in the community for at least 3 consecutive months. We used purposive quota sampling to ensure a proper representation of the Fiji population. Pneumococci were detected by real-time quantitative PCR, and molecular serotyping was done with microarray.

FINDINGS

3 years after PCV10 introduction, vaccine-serotype carriage prevalence declined, with adjusted prevalences (2015 vs 2012) of 0·56 (95% CI 0·34-0·93) in 5-8-week-old infants, 0·34 (0·23-0·49) in 12-23-month-olds, 0·47 (0·34-0·66) in 2-6-year-olds, and 0·43 (0·13-1·42) in caregivers. Reductions in PCV10 serotype carriage were evident in both main ethnic groups in Fiji; however, carriage of non-PCV10 serotypes increased in Indigenous Fijian infants and children. Density of PCV10 serotypes and non-PCV10 serotypes was lower in PCV10-vaccinated children aged 12-23 months than in PCV10-unvaccinated children of the same age group (PCV10 serotypes -0·56 [95% CI -0·98 to -0·15], p=0·0077; non-PCV10 serotypes -0·29 [-0·57 to -0·02], p=0·0334).

INTERPRETATION

Direct and indirect effects on pneumococcal carriage post-PCV10 are likely to result in reductions in pneumococcal disease, including in infants too young to be vaccinated. Serotype replacement in carriage in Fijian children, particularly Indigenous children, warrants further monitoring. Observed changes in pneumococcal density might be temporal rather than vaccine related.

FUNDING

Department of Foreign Affairs and Trade of the Australian Government through the Fiji Health Sector Support Program; Victorian Government's Operational Infrastructure Support Program; Bill & Melinda Gates Foundation.

Decreased relative risk of pneumococcal pneumonia during the last decade, a nested case-control study

Background

Streptococcus pneumoniae (SP) is one of the most common pathogens of Community-Acquired Pneumonia (CAP), but recent reports suggest that its incidence may be declining in relation to the use of the conjugate 13-valent pneumococcal vaccine in children. We compared the result of the immunochromatographic SP urinary antigen test (SPUAT) and clinical outcomes in patients with CAP admitted in two periods of time: 2001–2002(CAP1) and 2015–2016(CAP2).

Methods

This was a matched nested case-control study of two prospectively recorded cohorts of patients admitted with CAP, with SPUAT and blood culture performed in all patients. CAP2 cases and CAP1 controls were matched for age ± 4 years, sex, and Pneumonia Severity Index (PSI) score ± 10 points. Odds ratios (OR) for having SPUAT positive was estimated by conditional logistic regression. A multivariate model assessed the contribution of individual variables.

Results

Four hundred ninety-eight patients were recruited; 307 during the CAP1 and 191 during the CAP2 periods. Comparing both periods we observed differences, in age, PSI score, and the percentage of smokers, outpatients, previously immunized with pneumococcal vaccine, and positive SPUAT. On the other hand, mortality, admission from nursing homes, pneumococcal bacteremia and hospital admission were not different. After matching, pneumonia due to SP per the SPUAT was observed in 34(23.4%) of CAP1 and in 12(8.3%) of CAP2 patients (p < 0.001), and 6/145 CAP1 vs 33/145 CAP2 patients had received pneumococcal immunization before their admission (p < 0.001). A multivariate analysis confirmed that, independent of falling into PSI class 5, having not received the pneumococcal vaccine and having not survived the episode of pneumonia, there were two factors that increased the probability of having SPUAT positive: developing pneumonia during the CAP1 period (OR = 1.23) and having pneumococcal bacteremia (OR = 2.66).

Conclusion

We observed a reduction of the role of SP as pathogen, along with an increase in the number of patients who received pneumococcal immunization before admission, in 2015-2016 compared to 2001-2002. In addition, the use of conjugate 13-valent vaccine, starting in 2012 for childhood immunization, could be an additional factor contributing to these changes, as a result of early herd immunity in adults pneumonia.

Challenges for nationwide vaccine delivery in African countries

Vaccines are very effective in providing individual and community (herd) immunity against a range of diseases. In addition to protection against a range of diseases, vaccines also have social and economic benefits. However, for vaccines to be effective, routine immunization programmes must be undertaken regularly to ensure individual and community protection. Nonetheless, in many countries in Africa, vaccination coverage is low because governments struggle to deliver vaccines to the most remote areas, thus contributing to constant outbreaks of various vaccine-preventable diseases. African governments fail to deliver vaccines to a significant percentage of the target population due to many issues in key areas such as policy setting, programme management and financing, supply chain, global vaccine market, research and development of vaccines. This review gives an overview of the causes of these issues and what is currently being done to address them. This review will discuss the role of philanthropic organisations such as the Bill and Melinda Gates Foundation and global partnerships such as the global alliance for vaccines and immunizations in the development, purchase and delivery of vaccines.

Determining the pneumococcal conjugate vaccine coverage required for indirect protection against vaccine-type pneumococcal carriage in low and middle-income countries: a protocol for a prospective observational study

INTRODUCTION

Pneumococcal conjugate vaccines (PCVs) prevent disease through both direct protection of vaccinated individuals and indirect protection of unvaccinated individuals by reducing nasopharyngeal (NP) carriage and transmission of vaccine-type (VT) pneumococci. While the indirect effects of PCV vaccination are well described, the PCV coverage required to achieve the indirect effects is unknown. We will investigate the relationship between PCV coverage and VT carriage among undervaccinated children using hospital-based NP pneumococcal carriage surveillance at three sites in Asia and the Pacific.

METHODS AND ANALYSIS

We are recruiting cases, defined as children aged 2-59 months admitted to participating hospitals with acute respiratory infection in Lao People's Democratic Republic, Mongolia and Papua New Guinea. Thirteen-valent PCV status is obtained from written records. NP swabs are collected according to standard methods, screened using lytA qPCR and serotyped by microarray. Village-level vaccination coverage, for the resident communities of the recruited cases, is determined using administrative data or community survey. Our analysis will investigate the relationship between VT carriage among undervaccinated cases (indirect effects) and vaccine coverage using generalised estimating equations.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the relevant ethics committees at participating sites. The results are intended for publication in open-access peer-reviewed journals and will demonstrate methods suitable for low- and middle-income countries to monitor vaccine impact and inform vaccine policy makers about the PCV coverage required to achieve indirect protection.

Estimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory tract infections in 195 countries: a systematic analysis for the Global Burden of Disease Study 2015

BACKGROUND

The Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2015 provides an up-to-date analysis of the burden of lower respiratory tract infections (LRIs) in 195 countries. This study assesses cases, deaths, and aetiologies spanning the past 25 years and shows how the burden of LRI has changed in people of all ages.

METHODS

We estimated LRI mortality by age, sex, geography, and year using a modelling platform shared across most causes of death in the GBD 2015 study called the Cause of Death Ensemble model. We modelled LRI morbidity, including incidence and prevalence, using a meta-regression platform called DisMod-MR. We estimated aetiologies for LRI using two different counterfactual approaches, the first for viral pathogens, which incorporates the aetiology-specific risk of LRI and the prevalence of the aetiology in LRI episodes, and the second for bacterial pathogens, which uses a vaccine-probe approach. We used the Socio-demographic Index, which is a summary indicator derived from measures of income per capita, educational attainment, and fertility, to assess trends in LRI-related mortality. The two leading risk factors for LRI disability-adjusted life-years (DALYs), childhood undernutrition and air pollution, were used in a decomposition analysis to establish the relative contribution of changes in LRI DALYs.

FINDINGS

In 2015, we estimated that LRIs caused 2·74 million deaths (95% uncertainty interval [UI] 2·50 million to 2·86 million) and 103·0 million DALYs (95% UI 96·1 million to 109·1 million). LRIs have a disproportionate effect on children younger than 5 years, responsible for 704 000 deaths (95% UI 651 000-763 000) and 60.6 million DALYs (95ÙI 56·0-65·6). Between 2005 and 2015, the number of deaths due to LRI decreased by 36·9% (95% UI 31·6 to 42·0) in children younger than 5 years, and by 3·2% (95% UI -0·4 to 6·9) in all ages. Pneumococcal pneumonia caused 55·4% of LRI deaths in all ages, totalling 1 517 388 deaths (95% UI 857 940-2 183 791). Between 2005 and 2015, improvements in air pollution exposure were responsible for a 4·3% reduction in LRI DALYs and improvements in childhood undernutrition were responsible for an 8·9% reduction.

INTERPRETATION

LRIs are the leading infectious cause of death and the fifth-leading cause of death overall; they are the second-leading cause of DALYs. At the global level, the burden of LRIs has decreased dramatically in the last 10 years in children younger than 5 years, although the burden in people older than 70 years has increased in many regions. LRI remains a largely preventable disease and cause of death, and continued efforts to decrease indoor and ambient air pollution, improve childhood nutrition, and scale up the use of the pneumococcal conjugate vaccine in children and adults will be essential in reducing the global burden of LRI.

FUNDING

Bill & Melinda Gates Foundation.

Etiology of severe pneumonia in Ecuadorian children

BACKGROUND

In Latin America, community-acquired pneumonia remains a major cause of morbidity and mortality among children. Few studies have examined the etiology of pneumonia in Ecuador.

METHODS

This observational study was part of a randomized, double blind, placebo-controlled clinical trial conducted among children aged 2-59 months with severe pneumonia in Quito, Ecuador. Nasopharyngeal and blood samples were tested for bacterial and viral etiology by polymerase chain reaction. Risk factors for specific respiratory pathogens were also evaluated.

RESULTS

Among 406 children tested, 159 (39.2%) had respiratory syncytial virus (RSV), 71 (17.5%) had human metapneumovirus (hMPV), and 62 (15.3%) had adenovirus. Streptococcus pneumoniae was identified in 37 (9.2%) samples and Mycoplasma pneumoniae in three (0.74%) samples. The yearly circulation pattern of RSV (P = 0.0003) overlapped with S. pneumoniae, (P = 0.03) with most cases occurring in the rainy season. In multivariable analysis, risk factors for RSV included younger age (adjusted odds ratio [aOR] = 1.9, P = 0.01) and being underweight (aOR = 1.8, P = 0.04). Maternal education (aOR = 0.82, P = 0.003), pulse oximetry (aOR = 0.93, P = 0.005), and rales (aOR = 0.25, P = 0.007) were associated with influenza A. Younger age (aOR = 3.5, P = 0.007) and elevated baseline respiratory rate were associated with HPIV-3 infection (aOR = 0.94, P = 0.03).

CONCLUSION

These results indicate the importance of RSV and influenza, and potentially modifiable risk factors including undernutrition and future use of a RSV vaccine, when an effective vaccine becomes available.

TRIAL REGISTRATION

ClinicalTrials.gov NCT 00513929.