Choosing between 7-, 10- and 13-valent pneumococcal conjugate vaccines in childhood: a review of economic evaluations (2006-2014)

Novel method for production and purification of untagged pneumococcal surface protein A from clade 1

Streptococcus pneumoniae can cause diseases with high mortality and morbidity. The licensed vaccines are based on capsular polysaccharides and induce antibodies with low cross reactivity, leading to restricted coverage of serotypes. For surpassing this limitation, new pneumococcal vaccines are needed for induction of broader protection. One important candidate is the pneumococcal surface protein A (PspA), which can be classified in 6 clades and 3 families. We have reported an efficient process for production and purification of untagged recombinant PspA from clade 4 (PspA4Pro). We now aim to obtain a highly pure recombinant PspA from clade 1 (PspA1) to be included, together with PspA4Pro, in a vaccine formulation to broaden response against pneumococci. The vector pET28a-pspA1 was constructed and used to transform Escherichia coli BL21(DE3) strain. One clone with high production of PspA1 was selected and adapted to high-density fermentation (HDF) medium. After biomass production in 6 L HDF using a bioreactor, the purification was defined after testing 3 protocols. During the batch bioreactor cultivation, plasmid stability remained above 90% and acetate formation was not detected. The final protein purification process included treatment with a cationic detergent after lysis, anion exchange chromatography, cryoprecipitation, cation exchange chromatography, and multimodal chromatography. The final purification process showed PspA1 purity of 93% with low endotoxin content and an overall recovery above 20%. The novel established process can be easily scaled-up and proved to be efficient to obtain a highly pure untagged PspA1 for inclusion in vaccine formulations. KEY POINTS: • Purification strategy for recombinant PspA1 from Streptococcus pneumoniae • Downstream processing for untagged protein antigens, the case of PspA1 • Purification strategy for PspA variants relies on buried amino acids in their sequences.

Implementation challenges and real-world impacts of switching pediatric vaccines: A global systematic literature review

Switching a vaccine for another on a pediatric national immunization program is often done for the betterment of society. However, if poorly implemented, switching vaccines could result in suboptimal transitions with negative effects. A systematic review was conducted to evaluate the existing knowledge from identifiable documents on implementation challenges of pediatric vaccine switches and the real-world impact of those challenges. Thirty-three studies met the inclusion criteria. We synthesized three themes: vaccine availability, vaccination program deployment, and vaccine acceptability. Switching pediatric vaccines can pose unforeseen challenges to health-care systems worldwide and additional resources are often required to overcome those challenges. Yet, the magnitude of the impact, especially economic and societal, was frequently under-researched with variability in reporting. Therefore, an efficient vaccine switch requires a thorough consideration of the added benefits of replacing the existing vaccine, preparation, planning, additional resource allocation, implementation timing, public-private partnerships, outreach campaigns, and surveillance for program evaluation.

Pneumococcal Vaccination in Children: A Systematic Review and Meta-Analysis of Cost-Effectiveness Studies

OBJECTIVES

Pneumococcal conjugate vaccines (PCVs) have significantly reduced disease burden caused by Streptococcus pneumoniae, a leading cause of childhood morbidity and mortality globally. This systematic review and meta-analysis aimed to assess the incremental net benefit (INB) of the 13-valent PCV (PCV13) and 10-valent PCV (PCV10) in children.

METHODS

We performed a comprehensive search in several databases published before May 2022. Studies were included if they were cost-effectiveness or cost-utility analyses of PCV13 or PCV10 compared with no vaccination or with each other in children. Various monetary units were converted to purchasing power parity, adjusted to 2021 US dollars. The INBs were calculated and then pooled across studies stratified by country income level, perspective, and consideration of herd effects, using a random-effect model.

RESULTS

Seventy studies were included. When herd effects were considered, PCV13 was cost-effective compared with PCV10 from the payer perspective in both high-income countries (HICs) (INB, $103.94; 95% confidence interval, $75.28-$132.60) and low- and middle-income countries (LMICs) (INB, $53.49; 95% confidence interval, $30.42-$76.55) with statistical significance. These findings were robust across a series of sensitivity analyses. PCV13 was cost-effective compared with no vaccination across perspectives and consideration of herd effects in both HICs and LMICs, whereas findings were less consistent for PCV10.

CONCLUSION

PCVs were generally cost-effective compared with no vaccination in HICs and LMICs. Our study found that PCV13 was cost-effective compared with PCV10 when herd effects were considered from the payer perspective in both HICs and LMICs. The results are sensitive to the consideration of herd effects.

Cost-effectiveness of the 13-valent pneumococcal conjugate vaccine compared to the 10-valent vaccine in children: predictive analysis in the Ecuadorian context

Objective

To evaluate the cost-effectiveness and economic impact of changing childhood vaccination from the 10-valent pneumococcal conjugate vaccine (PCV10) to the 13-valent pneumococcal conjugate vaccine (PCV13) in the context of the Ecuadorian health system.

Methods

A Markov model was developed based on a hypothetical cohort of children <1 year old with a 2 + 1 vaccination schedule. The model incorporates the most impactful chronic sequelae of invasive pneumococcal disease: bilateral hearing loss, spasticity, neurological deficit, hydrocephalus and epilepsy. At the end of each annual Markov cycle, the children heal with/without sequelae or die. A time horizon of 5 years was considered. The analysis was done from the perspective of the Ministry of Health.

Key findings

Vaccination with PCV13 is cost-saving (US$ −2940/QALY) in relation to PCV10 considering indirect effects (‘herd effect’) of childhood vaccination over adult population (>65 years). So, PCV13 reduces incident cases of IPD in this adult population by 27.8% compared to PCV10. Simulation of the model in a cohort of 100 000 children <1 year old showed an incidence of 25 cases of IPD with PCV13 versus 40 cases with PCV10, that is, a reduction of 37.5%. A reduction compared to PCV10 in the incidence of pneumonia and meningitis of 30.2 and 57.1%, respectively, was demonstrated. PCV13 decreased mortality by 32% compared to PCV10.

Conclusions

Vaccination with PCV13 is cost-saving in the Ecuadorian health context and significantly reduces morbidity and mortality in children <5 years and in adults >65 years due to the herd effect. The probabilistic analysis showed consistency in the results.

Identification of the Bartonella autotransporter CFA as a protective antigen and hypervariable target of neutralizing antibodies in mice

Bartonella infections represent a significant burden to human health and are difficult to cure. Protective Bartonella vaccines are not available. Acquired immunity to Bartonella infection could provide a blueprint for vaccine design but remains incompletely defined. Moreover, bacterial immune evasion mechanisms have the potential to thwart vaccination efforts. Our study in a model of a natural Bartonella–host relationship revealed that antibody-mediated prevention of bacterial attachment to erythrocytes is sufficient for protection. We identified the bacterial surface determinant CFA (CAMP-like factor autotransporter) as a target of protective antibodies. While immunization with CFA protected against challenge with the homologous Bartonella isolate, extensive variability of CFA already at the strain level revealed bacterial immune evasion mechanisms with implications for Bartonella vaccine design.

The bacterial genus Bartonella comprises numerous emerging pathogens that cause a broad spectrum of disease manifestations in humans. The targets and mechanisms of the anti-Bartonella immune defense are ill-defined and bacterial immune evasion strategies remain elusive. We found that experimentally infected mice resolved Bartonella infection by mounting antibody responses that neutralized the bacteria, preventing their attachment to erythrocytes and suppressing bacteremia independent of complement or Fc receptors. Bartonella-neutralizing antibody responses were rapidly induced and depended on CD40 signaling but not on affinity maturation. We cloned neutralizing monoclonal antibodies (mAbs) and by mass spectrometry identified the bacterial autotransporter CFA (CAMP-like factor autotransporter) as a neutralizing antibody target. Vaccination against CFA suppressed Bartonella bacteremia, validating CFA as a protective antigen. We mapped Bartonella-neutralizing mAb binding to a domain in CFA that we found is hypervariable in both human and mouse pathogenic strains, indicating mutational antibody evasion at the Bartonella subspecies level. These insights into Bartonella immunity and immune evasion provide a conceptual framework for vaccine development, identifying important challenges in this endeavor.

The broader impacts of otitis media and sequelae for informing economic evaluations of pneumococcal conjugate vaccines

INTRODUCTION

Otitis media (OM) is a common childhood infection. Pneumococcal conjugate vaccines (PCVs) prevent OM episodes, thereby reducing short- and long-term clinical, economic, humanistic, and societal consequences. Most economic evaluations of PCVs focus on direct health gains and cost savings from prevented acute episodes but do not fully account for the broader societal impacts of OM prevention.

AREAS COVERED

This review explores the broader burden of OM on children, caregivers, and society to better inform future economic evaluations of PCVs.

EXPERT OPINION

OM causes a substantial burden to society through long-term sequelae, productivity losses, reduced quality of life for children and caregivers, and contribution to antimicrobial resistance from inappropriate antibiotic use. The effect of PCVs on acute OM has been recognized globally, yet the broader impact has not been consistently quantified, studied, or communicated. Economic evaluations of PCVs must evolve to include broader effects for patients, caregivers, and society from OM prevention. Future PCVs with broader coverage may further reduce OM incidence and antimicrobial resistance, but optimal uptake will depend on increasing the recognition and use of novel frameworks that include broader benefits. Communicating the full value of PCVs to decision makers may result in wider access and positive societal returns.

The Cost-Effectiveness of 13-Valent Pneumococcal Conjugate Vaccine in Seven Chinese Cities

Objective: This study estimates the cost-effectiveness of vaccination with the 13-valent pneumococcal conjugate vaccine (PCV13) among infants in Beijing, Shanghai, Shenzhen, Chengdu, Karamay, Qingdao, and Suzhou. Methods: A previously published cost-effectiveness model comparing vaccination with PCV13 to no vaccination was localized to the included Chinese cities. A systematic literature review was undertaken to identify age-specific incidence rates for pneumococcal bacteremia, pneumococcal meningitis, pneumonia, and otitis media (AOM). Age-specific direct medical costs of treating the included pneumococcal diseases were taken from the Chinese Health Insurance Association database. The base case analysis evaluated vaccine efficacy using direct effect and indirect effects (DE+ IDE). A subsequent scenario analysis evaluated the model outcomes if only DE was considered. A vaccination rate of 70% was used. The model reported outcomes over a one-year period after it was assumed the vaccine effects had reached a steady state (5–7 years after vaccine introduction) to include the direct and indirect effects of vaccination. Health outcomes were discounted at 5% during the steady-state period. Results: Vaccination with PCV13 was cost-effective in the base case analysis for all included cities with the incremental cost-effectiveness ratio (ICER) ranging from 1145 CNY(Shenzhen) to 15,422 CNY (Qingdao) per quality-adjusted life-year (QALY) gained. PCV13 was the dominant strategy in Shanghai with lower incremental costs and higher incremental QALYs. PCV13 remained cost-effective in the DE-only analysis with all ICERs falling below a cost-effectiveness threshold of three times GDP per capita in each city. Conclusions: Vaccination with PCV13 was a cost-effective strategy in the analyzed cities for both the DE-only and DE + IDE analyses. PCV13 became very cost-effective when a vaccination rate was reached where IDE is observed.

Population impact and effectiveness of sequential 13-valent pneumococcal conjugate and monovalent rotavirus vaccine introduction on infant mortality: prospective birth cohort studies from Malawi

Background

Pneumococcal conjugate vaccine (PCV) and rotavirus vaccine (RV) are key tools for reducing common causes of infant mortality. However, measurement of population-level mortality impact is lacking from sub-Saharan Africa. We evaluated mortality impact and vaccine effectiveness (VE) of PCV13 introduced in November 2011, with subsequent RV1 roll-out in October 2012, in Malawi.

Methods

We conducted two independent community-based birth cohort studies. Study 1, in northern Malawi (40000population), evaluated population impact using change-point analysis and negative-binomial regression of non-traumatic 14–51-week infant mortality preintroduction (1 January 2004 to 31 September 2011) and postintroduction (1 October 2011 to 1 July 2019), and against three-dose coverage. Study 2, in central Malawi (465 000 population), was recruited from 24 November 2011 to 1 June 2015. In the absence of preintroduction data, individual three-dose versus zero-dose VE was estimated using individual-level Cox survival models. In both cohorts, infants were followed with household visits to ascertain vaccination, socioeconomic and survival status. Verbal autopsies were conducted for deaths.

Results

Study 1 included 20 291 live births and 216 infant deaths. Mortality decreased by 28.6% (95% CI: 15.3 to 39.8) post-PCV13 introduction. A change point was identified in November 2012. Study 2 registered 50 731 live births, with 454 deaths. Infant mortality decreased from 17 to 10/1000 live births during the study period. Adjusted VE was 44.6% overall (95% CI: 23.0 to 59.1) and 48.3% (95% CI: −5.9 to 74.1) against combined acute respiratory infection, meningitis and sepsis-associated mortality.

Conclusion

These data provide population-level evidence of infant mortality reduction following sequential PCV13 and RV1 introduction into an established immunisation programme in Malawi. These data support increasing coverage of vaccine programmes in high-burden settings.

The impact and cost-effectiveness of introducing the 10-valent pneumococcal conjugate vaccine into the paediatric immunisation programme in Iceland-A population-based time series analysis

INTRODUCTION

Streptococcus pneumoniae is a cause of infections that range in severity from acute otitis media (AOM) to pneumonia and invasive pneumococcal disease (IPD). The 10-valent pneumococcal conjugate vaccine (PHiD-CV10) was introduced into the Icelandic paediatric immunisation programme in 2011. The aim was to estimate the population impact and cost-effectiveness of PHiD-CV10 introduction.

METHODS

Data on primary care visits from 2005-2015 and hospitalisations from 2005-2017 were obtained from population-based registries. A Bayesian time series analysis with synthetic controls was employed to estimate the number of cases of AOM, pneumonia and IPD that would have occurred between 2013-2017, had PHiD-CV10 not been introduced. Prevented cases were calculated by subtracting the observed number of cases from this estimate. The cost of the programme was calculated accounting for cost-savings due to prevented cases.

RESULTS

The introduction of PHiD-CV10 prevented 13,767 (95% credible interval [CI] 2,511-29,410) visits for AOM from 2013-2015, and prevented 1,814 (95%CI -523-4,512) hospitalisations for pneumonia and 53 (95%CI -17-177) admissions for IPD from 2013-2017. Visits for AOM decreased both among young children and among children 4-19 years of age, with rate ratios between 0.72-0.89. Decreases were observed in both pneumonia hospitalisations (rate ratios between 0.67-0.92) and IPD (rate ratios between 0.27-0.94). The total cost of implementing PHiD-CV10 in Iceland was -7,463,176 United States Dollars (USD) (95%CI -16,159,551-582,135) with 2.1 USD (95%CI 0.2-4.7) saved for every 1 USD spent.

CONCLUSIONS

The introduction of PHiD-CV10 was associated with large decreases in visits and hospitalisations for infections commonly caused by pneumococcus and was cost-saving during the first five years of the immunisation programme.

A systematic literature review of economic evaluations of pneumococcal conjugate vaccines in east and southeast Asia (2006-2019)

INTRODUCTION

Pneumococcal infections can lead to serious invasive diseases such as meningitis, septicemia and pneumonia, as well as milder but more common illnesses such as sinusitis and otitis media. The World Health Organization (WHO) recommends the inclusion of pneumococcal conjugate vaccines (PCVs) in infant National Immunization Program (NIP) programs worldwide. Decision-makers in Asian countries planning to introduce PCVs in their respective NIP will need a comprehensive evidence of effectiveness of PCVs at the population level and economic evidence including cost-effectiveness.

AREAS COVERED

A systematic literature review (from 1/1/2016 to 10/11/2019) of PCVs in East and Southeast Asia to understand (1) the contributing factors to cost-effectiveness results of PCVs and (2) whether gaps in evidence exist suggesting why the region may have yet to implement full NIPs.

EXPERT OPINION

In East and Southeast Asia, vaccination with PCVs was found to significantly reduce the mortality and morbidity of pneumococcal diseases and was cost-effective compared to no vaccination. Study assumptions, specifically vaccine local acquisition, the inclusion or exclusion of indirect effects (serotype replacement and herd effect), cross-protection, and protection against nontypeable haemophilus influenzae and serotype 3, were the main drivers of cost-effectiveness.

Comparison of PCV-10 and PCV-13 vaccine coverage for invasive pneumococcal isolates obtained across Canadian geographic regions, SAVE 2011 to 2017

To assess the coverage of invasive Streptococcus pneumoniae by pneumococcal conjugate vaccines (PCV)-10 and PCV-13 across Canada. In total, 9166 invasive S. pneumoniae isolates were collected as part of the SAVE 2011 to 2017 study. Serotyping was performed by the Quellung reaction and antimicrobial susceptibility testing was performed using CLSI methods. The proportion of both PCV-10 and PCV-13 serotypes decreased significantly (P < 0.0001) from 2011 (26.7% and 48.0%, respectively) to 2017 (11.2% and 26.2%). For central, western, and eastern regions of Canada, PCV-13 provided significantly greater (P < 0.0001) coverage at 33.7% (2060/6110), 23.0% (456/1985), and 36.3% (389/1071), respectively, compared to PCV-10 at 15.4% (939/6110), 10.1% (201/1985), and 15.8% (169/1071) coverage. PCV-13 provided significantly greater coverage (53.3%, 282/529) of multidrug-resistant (MDR) isolates (resistant to ≥3 antimicrobial classes) than PCV-10 (14.6%, 77/529, P < 0.0001). PCV-13 provided significantly greater coverage of invasive S. pneumoniae serotypes, as well as coverage of MDR isolates, than PCV-10.

Dynamic changes in paediatric invasive pneumococcal disease after sequential switches of conjugate vaccine in Belgium: a national retrospective observational study

BACKGROUND

Ten-valent and 13-valent pneumococcal conjugate vaccines (PCVs) have shown important benefits by decreasing invasive pneumococcal disease caused by vaccine serotypes. Belgium had an uncommon situation with sequential use of PCV7, PCV13, and PCV10 in the childhood vaccination programmes between 2007 and 2018. We aimed to analyse the changes in incidence of invasive pneumococcal disease and serotype distribution in children throughout this period.

METHODS

Streptococcus pneumoniae isolates were obtained from patients with invasive pneumococcal disease in Belgium between 2007 and 2018 by the national laboratory-based surveillance. Paediatric invasive pneumococcal disease incidence, serotype distribution, and antimicrobial susceptibility were analysed in periods during which PCV7 (2009-10), PCV13 (2013-14), both PCV13 and PCV10 (2015-16), and PCV10 (2017-18) were used. Incidence rates and trends were compared. Vaccination status was collected. For a subset of serotype 19A isolates, multilocus sequence type was identified.

FINDINGS

After a decrease in PCV7 serotype invasive pneumococcal disease was observed during the PCV7 period, total paediatric invasive pneumococcal disease incidence significantly declined during the PCV13 period (-2·6% monthly, p<0·0001). During the PCV13-PCV10 period (2015-16), the lowest mean in paediatric invasive pneumococcal disease incidence was achieved, but the incidence increased again during the PCV10 period (2017-18), especially in children younger than 2 years (+1·7% monthly; p=0·028). This increase was mainly due to a significant rise in serotype 19A invasive pneumococcal disease incidence in the PCV10 period compared with the PCV13 period (p<0·0001), making serotype 19A the predominant serotype in paediatric invasive pneumococcal disease in the PCV10 period. Genetic diversity within the 2017-18 serotype 19A collection was seen, with two predominant clones, ST416 and ST994, that were infrequently observed before PCV10 introduction. In 2018, among children younger than 5 years with invasive pneumococcal disease who were correctly vaccinated, 37% (37 of 100) had PCV13 serotype invasive pneumococcal disease, all caused by serotype 19A and serotype 3.

INTERPRETATION

After a significant decrease during the PCV13 period, paediatric invasive pneumococcal disease incidence increased again during the PCV10 period. This observation mainly resulted from a significant increase of serotype 19A cases. During the PCV10 period, dominant serotype 19A clones differed from those detected during previous vaccine periods. Whether changes in epidemiology resulted from the vaccine switch or also from natural evolution remains to be further elucidated.

FUNDING

The Belgian National Reference is funded by the Belgian National Institute for Health and Disability Insurance and the whole genome sequencing by an investigator-initiated research grant from Pfizer.

Estimating the Impact of Switching from a Lower to Higher Valent Pneumococcal Conjugate Vaccine in Colombia, Finland, and The Netherlands: A Cost-Effectiveness Analysis

INTRODUCTION

Widespread use of ten-valent (Synflorix™, GSK) or 13-valent (Prevenar 13™; Pfizer) conjugate vaccination programs has effectively reduced invasive pneumococcal disease (IPD) globally. However, IPD caused by serotypes not contained within the respective vaccines continues to increase, notably serotypes 3, 6A, and 19A in countries using lower-valent vaccines. Our objective was to estimate the clinical and economic benefit of replacing PCV10 with PCV13 in Colombia, Finland, and The Netherlands.

METHODS

Country-specific databases, supplemented with published and unpublished data, informed the historical incidence of pneumococcal disease as well as direct and indirect medical costs. A decision-analytic forecasting model was applied, and both costs and outcomes were discounted. The observed invasive pneumococcal disease (IPD) trends from each country were used to forecast the future number of IPD cases given a PCV13 or PCV10 program.

RESULTS

Over a 5-year time horizon, a switch to a PCV13 program was estimated to reduce overall IPD among 0-2 year olds by an incremental - 37.6% in Colombia, - 32.9% in Finland, and - 26% in The Netherlands, respectively, over PCV10. Adults > 65 years experienced a comparable incremental decrease in overall IPD in Colombia (- 32.2%), Finland (- 15%), and The Netherlands (- 3.7%). Serotypes 3, 6A, and 19A drove the incremental decrease in disease for PCV13 over PCV10 in both age groups. A PCV13 program was dominant in Colombia and Finland and cost-effective in The Netherlands at 1 × GDP per capita (€34,054/QALY).

CONCLUSION

In Colombia, Finland, and The Netherlands, countries with diverse epidemiologic and population distributions, switching from a PCV10 to PCV13 program would significantly reduce the burden of IPD in all three countries in as few as 5 years.

Trends in governmental expenditure on vaccination programmes in the Netherlands, a historical analysis

BACKGROUND

Health economic evaluations are often required before implementing a vaccination programme. Such evaluations rarely consider the historical context of a vaccination programme. We review the financial history of vaccination programmes in the Netherlands, and compare these to demographic and macroeconomic developments as well as avoided mortality burden.

METHODS

Previously uncatalogued historical expenditures on the Dutch National Immunisation Programme (NIP) and influenza vaccination were obtained from official reports. Costs were adjusted for inflation using Consumer Price Indices and expressed in Euro of 2016. Estimates on mortality burden averted were obtained from previous research and used to calculate the ratio of expenses to averted mortality burden for vaccinations against diphtheria, tetanus, pertussis, polio, measles, mumps and rubella for birth cohorts 1953-1992.

RESULTS

Developments towards a uniform government funded NIP started early 1950s with vaccinations against diphtheria, pertussis and tetanus, culminating in its official launch in 1957 together with polio vaccinations. Since the 1980s, expenditure increased nearly five-fold mostly due to the addition of new vaccines, while spending on already implemented vaccinations tended to decline. Overall, expenditure increased from € 5 million in 1957 to € 93 million in 2014. Relative to total healthcare expenditure, the NIP contributed little, ranging between 0.05% and 0.14%. Spending on influenza vaccination increased from € 37 million in 1996 to € 52 million in 2014, while relative to total healthcare expenditure it decreased from 0.069% to 0.055%. In 2014, 0.15% of healthcare expenditure and € 533 per birth was spent on vaccination programmes. Overall, for birth cohorts 1953-1992, € 5.4 thousand (95% confidence interval: 4.0-7.3) was expended per year-of-life-lost averted.

CONCLUSION

The actual costs per year-of-life gained are more favorable than estimated here since averted medical costs were not included. Although expenditure on vaccination programmes increased substantially, the contribution to overall healthcare expenditure remained small.

Effect and cost-effectiveness of pneumococcal conjugate vaccination: a global modelling analysis

BACKGROUND

Introduction of pneumococcal conjugate vaccines (PCVs) has substantially reduced disease burden due to Streptococcus pneumoniae, a leading cause of childhood morbidity and mortality globally. However, PCVs are among the most expensive vaccines, hindering their introduction in some settings and threatening sustainability in others. We aimed to assess the effect and cost-effectiveness of introduction of 13-valent PCV (PCV13) vaccination globally.

METHODS

We assessed the incremental cost-effectiveness ratio of PCV13 introduction by integrating two models: an ecological model (a parsimonious, mechanistic model validated with data from post-seven-valent PCV introduction in 13 high-income settings) to predict the effect of PCV on childhood invasive pneumococcal disease, and a decision-tree model to predict a range of clinical presentations and economic outcomes under vaccination and no-vaccination strategies. The models followed 30 birth cohorts up to age 5 years in 180 countries from 2015 to 2045. One-way scenario and probabilistic sensitivity analyses were done to explore model uncertainties.

FINDINGS

We estimate that global PCV13 use could prevent 0·399 million child deaths (95% credible interval 0·208 million to 0·711 million) and 54·6 million disease episodes (51·8 million to 58·1 million) annually. Global vaccine costs (in 2015 international dollars) of $15·5 billion could be partially offset by health-care savings of $3·19 billion (2·62 billion to 3·92 billion) and societal cost savings of $2·64 billion (2·13 billion to 3·28 billion). PCV13 use is probably cost-effective in all six UN regions. The 71 countries eligible for support from Gavi, the Vaccine Alliance, account for 83% of PCV13-preventable deaths but only 18% of global vaccination costs. The expected cost of PCV vaccination globally is around $16 billion per year.

INTERPRETATION

Our findings highlight the value of Gavi's support for PCV introduction in low-income countries and of efforts to improve the affordability of PCVs in countries not eligible for, or transitioning from, Gavi support.

FUNDING

World Health Organization; Gavi, the Vaccine Alliance; and the Bill & Melinda Gates Foundation.

Clinical characteristics and antimicrobial resistance of pneumococcal isolates of pediatric invasive pneumococcal disease in China

Purpose

Streptococcus pneumoniae causes serious infections globally, including invasive pneumococcal disease (IPD). We analyze clinical features of pediatric IPD cases identified in China and antibiotic susceptibility of isolated pneumococcal strains.

Methods

Confirmed pediatric IPD patients were prospectively recruited to the study. Symptoms at the time of hospitalization, laboratory tests, antimicrobial susceptibility of pneumococcal isolates, treatments, hospital stay, and residual findings at discharge were analyzed systematically.

Results

From January 2008 to December 2017, a total of 123 hospitalized children diagnosed with IPD were enrolled: 68 from pediatric departments of Xinhua Hospital, and 55 from Lanzhou University Second Hospital. Of these pediatric IPD patients, 81 (65.86%) were male, and 98 (79.67%) <5 years old. Most cases (96, 78.05%) were diagnosed during the cold season between September and February. Sepsis was observed in 82 (66.67%) patients, 48 (39.02%) children were diagnosed with meningitis, 41 (33.33%) with pneumonia, 30 (24.39%) with pleurisy, and 4 (3.25%) with osteomyelitis. Underlying diseases were noted in 35 (28.45%) patients and concurrent infections in 45 (36.58%). The overall mortality rate was 2.44%. IPD children who developed sepsis and necrotizing pneumonia showed higher proportions of intensive care-unit admission, intravenous γ-globulin, glucocorticoid use, hemofiltration and ventilator, and longer duration of fever, hospital stay, and antibiotic use than nonsepsis and pneumonia subjects. Antimicrobial resistance of S. pneumoniae showed a highly unsusceptible rate for erythromycin (96.75%), trimethoprim-sulfamethoxazole (79.67%), and tetracycline (77.23%). All isolates were sensitive to vancomycin, linezolid, and levofloxacin.

Conclusion

Clinical symptoms were severe in the majority of pediatric IPD patients. More intensive treatments were demanded for IPD children with sepsis and necrotizing pneumonia. High resistance rates for erythromycin, trimethoprim–sulfamethoxazole, and tetracycline were found.

Model Comparisons of the Effectiveness and Cost-Effectiveness of Vaccination: A Systematic Review of the Literature

OBJECTIVES

To describe all published articles that have conducted comparisons of model-based effectiveness and cost-effectiveness results in the field of vaccination. Specific objectives were to 1) describe the methodologies used and 2) identify the strengths and limitations of the studies.

METHODS

We systematically searched MEDLINE and Embase databases for studies that compared predictions of effectiveness and cost-effectiveness of vaccination of two or more mathematical models. We categorized studies into two groups on the basis of their data source for comparison (previously published results or new simulation results) and performed a qualitative synthesis of study conclusions.

RESULTS

We identified 115 eligible articles (only 5% generated new simulations from the reviewed models) examining the effectiveness and cost-effectiveness of vaccination against 14 pathogens (69% of studies examined human papillomavirus, influenza, and/or pneumococcal vaccines). The goal of most of studies was to summarize evidence for vaccination policy decisions, and cost-effectiveness was the most frequent outcome examined. Only 33%, 25%, and 3% of studies followed a systematic approach to identify eligible studies, assessed the quality of studies, and performed a quantitative synthesis of results, respectively. A greater proportion of model comparisons using published studies followed a systematic approach to identify eligible studies and to assess their quality, whereas more studies using new simulations performed quantitative synthesis of results and identified drivers of model conclusions. Most comparative modeling studies concluded that vaccination was cost-effective.

CONCLUSIONS

Given the variability in methods used to conduct/report comparative modeling studies, guidelines are required to enhance their quality and transparency and to provide better tools for decision making.

Estimating the cost-effectiveness of an infant 13-valent pneumococcal conjugate vaccine national immunization program in China

Background

The burden of pneumococcal disease in China is high, and a 13-valent pneumococcal conjugate vaccine (PCV13) recently received regulatory approval and is available to Chinese infants. PCV13 protects against the most prevalent serotypes causing invasive pneumococcal disease (IPD) in China, but will not provide full societal benefits until made broadly available through a national immunization program (NIP).

Objective

To estimate clinical and economic benefits of introducing PCV13 into a NIP in China using local cost estimates and accounting for variability in vaccine uptake and indirect (herd protection) effects.

Methods

We developed a population model to estimate the effect of PCV13 introduction in China. Modeled health states included meningitis, bacteremia, pneumonia (PNE), acute otitis media, death and sequelae, and no disease. Direct healthcare costs and disease incidence data for IPD and PNE were derived from the China Health Insurance and Research Association database; all other parameters were derived from published literature. We estimated total disease cases and associated costs, quality-adjusted life years (QALYs), and deaths for three scenarios from a Chinese Payer Perspective: (1) direct effects only, (2) direct+indirect effects for IPD only, and (3) direct+indirect effects for IPD and inpatient PNE.

Results

Scenario (1) resulted in 370.3 thousand QALYs gained and 12.8 thousand deaths avoided versus no vaccination. In scenarios (2) and (3), the PCV13 NIP gained 383.2 thousand and 3,580 thousand QALYs, and avoided 13.1 thousand and 147.5 thousand deaths versus no vaccination, respectively. In all three scenarios, the vaccination cost was offset by cost reductions from prevented disease yielding net costs of ¥29,362.32 million, ¥29,334.29 million, and ¥13,524.72 million, respectively. All resulting incremental cost-effectiveness ratios fell below a 2x China GDP cost-effectiveness threshold across a range of potential vaccine prices.

Discussion

Initiation of a PCV13 NIP in China incurs large upfront costs but is good value for money, and is likely to prevent substantial cases of disease among children and non-vaccinated individuals.

Immunogenicity and Reactogenicity of DTPa-HBV-IPV/Hib and PHiD-CV When Coadministered With MenACWY-TT in Infants: Results of an Open, Randomized Trial

BACKGROUND

This study evaluated the immunogenicity and reactogenicity of a combined diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus virus-Haemophilus influenzae type b vaccine (DTPa-HBV-IPV/Hib) and a 10-valent pneumococcal conjugate vaccine (PHiD-CV) coadministered with a quadrivalent meningococcal conjugate vaccine (MenACWY-TT) in infants/toddlers.

METHODS

In this open, controlled, phase III study (NCT01144663), 2095 healthy infants were randomized (1:1:1:1) into 4 groups to receive MenACWY-TT at 2, 3, 4 and 12 months of age or MenACWY-TT, MenC-CRM197, or MenC-TT at 2, 4 and 12 months of age. All participants received PHiD-CV and DTPa-HBV-IPV/Hib at 2, 3, 4 and 12 months of age. Immunogenicity of DTPa-HBV-IPV/Hib was evaluated in exclusive randomized subsets of 25% of participants from each group postprimary, prebooster and postbooster vaccination, whereas immunogenicity of PHiD-CV was evaluated at all time points. Reactogenicity was evaluated on the total vaccinated cohorts during 8 days after each vaccination.

RESULTS

For each DTPa-HBV-IPV/Hib antigen, ≥97.2%, ≥76.5% and ≥97.9% of participants had seropositive/seroprotective levels 1 month postprimary vaccination, before the booster dose and 1 month postbooster, respectively. For each vaccine pneumococcal serotype, ≥74.0% of infants had antibody concentrations ≥0.35 μg/mL at 1 month postprimary vaccination, and robust increases in antibody geometric mean concentrations were observed from prebooster to postbooster. Redness was the most frequent solicited local symptom at the DTPa-HBV-IPV/Hib and PHiD-CV injection sites, reported after up to 47.7% and 57.0% of doses postprimary and postbooster vaccination, respectively.

CONCLUSIONS

Primary and booster vaccinations of infants/toddlers with DTPa-HBV-IPV/Hib and PHiD-CV coadministered with MenACWY-TT were immunogenic with clinically acceptable reactogenicity profiles. These results support the coadministration of MenACWY-TT with routine childhood vaccines.

Multi-Envelope HIV-1 Vaccine Development: Two Targeted Immune Pathways, One Desired Protective Outcome

In 2016, there were more than 30 million individuals living with HIV-1, ∼1.8 million new HIV-1 infections, and ∼1 million HIV-1-related deaths according to UNAIDS ( unaids.org ). Hence, a preventive HIV-1 vaccine remains a global priority. The variant envelopes of HIV-1 present a significant obstacle to vaccine development and the vaccine field has realized that immunization with a single HIV-1 envelope protein will not be sufficient to generate broadly neutralizing antibodies. Here we describe two nonmutually exclusive, targeted pathways with which a multi-envelope HIV-1 vaccine may generate protective immune responses against variant HIV-1. Pathways include (i) the induction of a polyclonal immune response, comprising a plethora of antibodies with subset-reactive and cross-reactive specificities, together able to neutralize diverse HIV-1 (termed Poly-nAb in this report) and (ii) the induction of one or a few monoclonal antibodies, each with a broadly neutralizing specificity (bnAb). With each pathway in mind, we describe challenges and strategies that may ultimately support HIV-1 vaccine success.

Cost-effectiveness analysis of a universal mass vaccination program with a PHiD-CV 2+1 schedule in Malaysia

Background

Currently, two pediatric pneumococcal conjugate vaccines are available in the private market of Malaysia—13-valent pneumococcal conjugate vaccine (PCV13) and pneumococcal polysaccharide and non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV). This study aimed to evaluate the cost-effectiveness of a universal mass vaccination program with a PHiD-CV 2+1 schedule versus no vaccination or with a PCV13 2+1 schedule in Malaysia.

Methods

A published Markov cohort model was adapted to evaluate the epidemiological and economic consequences of programs with no vaccination, a PHiD-CV 2+1 schedule or a PCV13 2+1 schedule over a 10-year time horizon. Disease cases, deaths, direct medical costs, quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICERs) were estimated. Locally published epidemiology and cost data were used whenever possible. Vaccine effectiveness and disutility data were based on the best available published data. All data inputs and assumptions were validated by local clinical and health economics experts. Analyses were conducted from the perspective of the Malaysian government for a birth cohort of 508,774. Costs and QALYs were discounted at 3% per annum. One-way and probabilistic sensitivity analyses were performed.

Results

Compared with no vaccination, a PHiD-CV 2+1 program was projected to prevent 1109 invasive pneumococcal disease (IPD), 24,679 pneumonia and 72,940 acute otitis media (AOM) cases and 103 IPD/pneumonia deaths over 10 years, with additional costs and QALYs of United States dollars (USD) 30.9 million and 1084 QALYs, respectively, at an ICER of USD 28,497/QALY. Compared with a PCV13 2+1 program, PHiD-CV 2+1 was projected to result in similar reductions in IPD cases (40 cases more) but significantly fewer AOM cases (30,001 cases less), with cost savings and additional QALYs gained of USD 5.2 million and 116 QALYs, respectively, demonstrating dominance over PCV13. Results were robust to variations in one-way and probabilistic sensitivity analyses.

Conclusions

A PHiD-CV 2+1 universal mass vaccination program could substantially reduce pneumococcal disease burden versus no vaccination, and was expected to be cost-effective in Malaysia. A PHiD-CV 2+1 program was also expected to be a dominant choice over a PCV13 2+1 program in Malaysia.

Electronic supplementary material

The online version of this article (doi:10.1186/s12962-017-0079-2) contains supplementary material, which is available to authorized users.

Exploring the acceptability of the available pneumococcal conjugate vaccines in Canadian health care professionals and immunization experts

BACKGROUND

In children, the 13 and 10-valent pneumoccocal conjugate vaccines (PCV13/10) are currently approved for the prevention of invasive pneumococcal disease (IPD). Acceptability is a key consideration in the implementation of a vaccine program and it is recognized that health professional's attitudes and opinions towards vaccines are independent predictors of the success of an immunization program. We aimed to survey the beliefs and attitudes for the two available PCVs in health care professionals and immunization experts.

FINDINGS

We interviewed 21 members of Canadian immunization committees and/or participants working in frontline healthcare delivery. Overall, participants predominantly preferred PCV-13 over PCV10. For most, AOM should not be taken into considerations in decisions for pneumococcal vaccination programs implementation. AOM was considered an important endpoint of the program but an ineffective measure of program success due to the lack of surveillance for the condition. Recent evidence pertaining to PCV10 cross-protection against 19A did not affect preference but had an impact on perceptions regarding pricing.

CONCLUSION

To consider implementing any changes to the current program, most participants would require more evidence regarding PCV10 cross-protection and effectiveness against OM. Decreasing vaccine price was cited as a positive outcome of funding both vaccines.

Cost Effectiveness of Pneumococcal Vaccination in Children in Low- and Middle-Income Countries: A Systematic Review

BACKGROUND

Although pneumococcal conjugate vaccines (PCVs) have been available for prevention of invasive pneumococcal disease (IPD) caused by Streptococcus pneumoniae (S. pneumoniae) for over a decade, their adoption into national immunization programmes in low- and middle-income countries (LMICs) is still limited. Economic evaluations (EEs) play a crucial role in support of evidence-informed decisions.

OBJECTIVE

This systematic review aims to provide a critical summary of EEs of PCVs and identify key drivers of EE findings in LMICs.

METHODS

We searched Scopus, ISI Web of Science, PubMed, Embase and Cochrane Central from their inception to 30 September 2015 and limited the search to LMICs. The search was undertaken using the search strings 'pneumococc* AND conjugat* AND (vaccin* OR immun*)' AND 'economic OR cost-effectiveness OR cost-benefit OR cost-utility OR cost-effectiveness OR cost-benefit OR cost-utility' in the abstract, title or keyword fields. To be included, each study had to be a full EE of a PCV and conducted for an LMIC. Studies were extracted and reviewed by two authors. The review involved standard extraction of the study overview or the characteristics of the study, key drivers or parameters of the EE, assumptions behind the analyses and major areas of uncertainty.

RESULTS

Out of 134 records identified, 22 articles were included. Seven studies used a Markov model for analysis, while 15 studies used a decision-tree analytic model. Eighteen studies performed a cost-utility analysis (CUA), with disability-adjusted life-years, quality-adjusted life-years or life-years gained as a measure of health outcome, while four studies focused only on cost-effectiveness analysis (CEA). Both CEA and CUA findings were provided by eight studies. Herd effects and serotype replacement were considered in 10 and 13 studies, respectively. The current evidence shows that both the 10-valent and 13-valent PCVs are probably cost effective in comparison with the 7-valent PCV or no vaccination. The most influential parameters were vaccine efficacy and coverage (in 16 of 22 studies), vaccine price (in 13 of 22 studies), disease incidence (in 11 of 22 studies), mortality from IPD and pneumonia (in 8 of 22 studies) and herd effects (in 4 of 22 studies). The findings were found to be supportive of the products owned by the manufacturers.

CONCLUSION

Our review demonstrated that an infant PCV programme was a cost-effective intervention in most LMICs (in 20 of 22 studies included). The results were sensitive to vaccine efficacy, price, burden of disease and sponsorship. Decision makers should consider EE findings and affordability before adoption of PCVs.

Cost-effectiveness and Health Benefits of Pediatric 23-valent Pneumococcal Polysaccharide Vaccine, 7-valent Pneumococcal Conjugate Vaccine and Forecasting 13-valent Pneumococcal Conjugate Vaccine in China

BACKGROUND

Each year in China, approximately 700,000 children under 5 years old are diagnosed with pneumonia, and 30,000 die of the disease. Although 7-valent pneumococcal conjugate vaccine (PCV-7) and 23-valent pneumococcal polysaccharide vaccine (PPV-23) are available in China, the costs are borne by the consumer, resulting in low coverage for PCV-7. We aimed to conduct a simulation study to assess the cost-effectiveness and health benefits of PCV-7, 13-valent pneumococcal conjugate vaccine (PCV-13) and PPV-23 to prevent childhood pneumonia and other vaccine-preventive diseases in China.

METHODS

An economic evaluation was performed using a Markov simulation model. Parameters including demographic, epidemiological data, costs and efficacy of vaccines were obtained from previous studies. A hypothetical cohort of 100,000 newborns (focusing on pneumococcal diseases ≤7 years old) was followed up until death or 100 years of age. The model incorporated the impact of vaccination on reduction of incidence of pneumococcal diseases and mortality of children ≤7 years. Outcomes are presented in terms of disease cases averted, quality-adjusted life years (QALYs) and incremental cost-effectiveness ratio.

RESULTS

Under baseline assumptions, PPV-23 is currently the only cost-effective option, whereas PCV-13 showed the greatest impact on pneumococcal disease burden, reducing invasive pneumococcal diseases by 31.3%, pneumonia by 15.3% and gaining 73.8 QALYs (10,000 individuals at discount rate of 3%). Incremental cost-effectiveness ratios of PCV-13 and PCV-7 are US$29,460/QALY and US$104,094/QALY, respectively, showing no cost-effectiveness based on the World Health Organization recommended willingness-to-pay threshold. On the other hand, the incremental cost-effectiveness ratios of PCVs were most sensitive to vaccination costs; if it reduces 4.7% and 32.2% for PCV-7 and PCV-13, respectively, the vaccination will be cost-effective.

CONCLUSIONS

To scale up current vaccination strategies and achieve potential health benefits, the replacement of PCV-7 with PCV-13 should be considered. As well, PCV's costs need to be reduced by increasing public subsidies and providing financial support to poor families.

Response to Wu et al. - Cost-effectiveness analysis of infant pneumococcal vaccination in Malaysia and Hong Kong

A recently published paper that assessed the comparative cost-effectiveness of the 2 pneumococcal conjugate vaccines (PCVs) in Malaysia and Hong Kong reported that the 13-valent PCV vaccine (PCV13) is a better choice compared to the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV or PCV10) from both a payer and societal perspective as well as under various scenarios. However, the analysis relied on a large number of assumptions that were either erroneous or did not take into account the most recent body of evidence available. A rigorous evaluation of the underlying assumptions is necessary to present a fair and balanced analysis for decision-making.

Methodological Challenges to Economic Evaluations of Vaccines: Is a Common Approach Still Possible?

Economic evaluation of vaccination is a key tool to inform effective spending on vaccines. However, many evaluations have been criticised for failing to capture features of vaccines which are relevant to decision makers. These include broader societal benefits (such as improved educational achievement, economic growth and political stability), reduced health disparities, medical innovation, reduced hospital beds pressures, greater peace of mind and synergies in economic benefits with non-vaccine interventions. Also, the fiscal implications of vaccination programmes are not always made explicit. Alternative methodological frameworks have been proposed to better capture these benefits. However, any broadening of the methodology for economic evaluation must also involve evaluations of non-vaccine interventions, and hence may not always benefit vaccines given a fixed health-care budget. The scope of an economic evaluation must consider the budget from which vaccines are funded, and the decision-maker's stated aims for that spending to achieve.

Economic evaluation of pediatric influenza immunization program compared with other pediatric immunization programs: A systematic review

This study compared the economic value of pediatric immunisation programmes for influenza to those for rotavirus (RV), meningococcal disease (MD), pneumococcal disease (PD), human papillomavirus (HPV), hepatitis B (Hep B), and varicella reported in recent (2000 onwards) cost-effectiveness (CE) studies identified in a systematic review of PubMed, health technology, and vaccination databases. The systematic review yielded 51 economic evaluation studies of pediatric immunisation - 10 (20%) for influenza and 41 (80%) for the other selected diseases. The quality of the eligible articles was assessed using Drummond's checklist. Although inherent challenges and limitations exist when comparing economic evaluations of immunisation programmes, an overall comparison of the included studies demonstrated cost-effectiveness/cost saving for influenza from a European-Union-Five (EU5) and United States (US) perspective; point estimates for cost/quality-adjusted life-years (QALY) from dominance (cost-saving with more effect) to ≤45,444 were reported. The economic value of influenza programmes was comparable to the other vaccines of interest, with cost/QALY in general considerably lower than RV, Hep B, MD and PD. Independent of the perspective and type of analysis, the economic impact of a pediatric influenza immunisation program was influenced by vaccine efficacy, immunisation coverage, costs, and most significantly by herd immunity. This review suggests that pediatric influenza immunisation may offer a cost effective strategy when compared with HPV and varicella and possibly more value compared with other childhood vaccines (RV, Hep B, MD and PD).

Impact of the pneumococcal 10-valent vaccine on reducing hospitalization for community-acquired pneumonia in children

OBJECTIVE

To describe and analyze the occurrence of hospitalizations for community-acquired pneumonia in children before and after the pneumococcal 10-valent conjugate vaccine implementation into the National Immunization Program.

METHODS

This is an ecological study that includes records of children younger than one year old, vaccinated and not vaccinated with the pneumococcal 10-valent conjugate vaccine in the periods pre- and post-inclusion of the vaccine in the National Immunization Program in the area covered by the Regional Health Superintendence of Alfenas, state of Minas Gerais, Brazil. Vaccination was considered as the exposure factor and hospitalization for community-acquired pneumonia as the endpoint, using secondary annual data by municipality. The prevalence ratio and its 95% confidence interval (95%CI) were used to verify the association between variables. The Z test was used to calculate the difference between proportions.

RESULTS

Considering the 26 municipalities of the Regional Health Superintendence of Alfenas, there was a significant reduction in hospitalizations for community-acquired pneumonia in children younger than one year of age, with prevalence ratio (PR)=0.81 (95%CI: 0.74 to 0.89; p<0.05), indicating a 19% lower prevalence of hospitalization for community-acquired pneumonia in the post-vaccination period.

CONCLUSIONS

The results suggest the effectiveness of the pneumococcal 10-valent conjugate vaccine in preventing severe cases of community-acquired pneumonia in children younger than one year of age.

Impact of the pneumococcal 10-valent vaccine on reducing hospitalization for community-acquired pneumonia in children

OBJECTIVE

To describe and analyze the occurrence of hospitalizations for community-acquired pneumonia in children before and after the pneumococcal 10-valent conjugate vaccine implementation into the National Immunization Program.

METHODS

This is an ecological study that includes records of children younger than one year old, vaccinated and not vaccinated with the pneumococcal 10-valent conjugate vaccine in the periods pre- and post-inclusion of the vaccine in the National Immunization Program in the area covered by the Regional Health Superintendence of Alfenas, state of Minas Gerais, Brazil. Vaccination was considered as the exposure factor and hospitalization for community-acquired pneumonia as the endpoint, using secondary annual data by municipality. The prevalence ratio and its 95% confidence interval (95%CI) were used to verify the association between variables. The Z test was used to calculate the difference between proportions.

RESULTS

Considering the 26 municipalities of the Regional Health Superintendence of Alfenas, there was a significant reduction in hospitalizations for community-acquired pneumonia in children younger than one year of age, with prevalence ratio (PR)=0.81 (95%CI: 0.74 to 0.89; p<0.05), indicating a 19% lower prevalence of hospitalization for community-acquired pneumonia in the post-vaccination period.

CONCLUSIONS

The results suggest the effectiveness of the pneumococcal 10-valent conjugate vaccine in preventing severe cases of community-acquired pneumonia in children younger than one year of age.

Bacterial Infections Following Splenectomy for Malignant and Nonmalignant Hematologic Diseases

Splenectomy, while often necessary in otherwise healthy patients after major trauma, finds its primary indication for patients with underlying malignant or nonmalignant hematologic diseases. Indications of splenectomy for hematologic diseases have been reducing in the last few years, due to improved diagnostic and therapeutic tools. In high-income countries, there is a clear decrease over calendar time in the incidence of all indication splenectomy except nonmalignant hematologic diseases. However, splenectomy, even if with different modalities including laparoscopic splenectomy and partial splenectomy, continue to be a current surgical practice both in nonmalignant hematologic diseases, such as Immune Thrombocytopenic Purpura (ITP), Autoimmune Hemolytic Anemia (AIHA), Congenital Hemolytic Anemia such as Spherocytosis, Sickle Cell Anemia and Thalassemia and Malignant Hematological Disease, such as lymphoma. Today millions of people in the world are splenectomized. Splenectomy, independently of its cause, induces an early and late increase in the incidence of venous thromboembolism and infections. Infections remain the most dangerous complication of splenectomy. After splenectomy, the levels of antibody are preserved but there is a loss of memory B cells against pneumococcus and tetanus, and the loss of marginal zone monocytes deputed to immunological defense from capsulated bacteria. Commonly, the infections strictly correlated to the absence of the spleen or a decreased or absent splenic function are due to encapsulated bacteria that are the most virulent pathogens in this set of patients. Vaccination with polysaccharide and conjugate vaccines again Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis should be performed before the splenectomy. This practice reduces but does not eliminate the occurrence of overwhelming infections due to capsulated bacteria. At present, most of infections found in splenectomized patients are due to Gram-negative (G-) bacteria. The underlying disease is the most important factor in determining the frequency and severity of infections. So, splenectomy for malignant diseases has the major risk of infections.

Prevention of pneumococcal infections during mass gathering

The interest in mass gathering and its implications has been increasing due to globalization and international travel. The potential occurrence of infectious disease outbreaks during mass gathering is most feared. In this context, respiratory tract infections are of great concern due to crowding in a limited space which facilitates and magnifies the potential of disease spread among attendees. Pneumococcal disease is best described among pilgrims to Makkah and vaccination is one of the methods for the prevention of this disease. Pneumonia was described in a mass gathering with a prevalence of 4.8/100,000 pilgrims and contributes to 15-39% of hospitalizations. Various studies showed that 7-37% of pilgrims are 65 y of age or older. The uptake of pneumococcal vaccine among pilgrims is low at 5%. There is no available data to make strong recommendations for S. pneumoniae vaccination of all pilgrims, it is important that a high risk population receive the indicated vaccination. We reviewed the available literature on the burden of pneumococcal infections during mass gathering and evaluate the available literature on pneumococcal vaccinations for attendees of mass gathering.