Pediatric invasive pneumococcal disease in the United States in the era of pneumococcal conjugate vaccines

Understanding healthcare providers' preferred attributes of pediatric pneumococcal conjugate vaccines in the United States

As higher-valent pneumococcal conjugate vaccines (PCVs) become available for pediatric populations in the US, it is important to understand healthcare provider (HCP) preferences for and acceptability of PCVs. US HCPs (pediatricians, family medicine physicians and advanced practitioners) completed an online, cross-sectional survey between March and April 2023. HCPs were eligible if they recommended or prescribed vaccines to children age <24 months, spent ≥25% of their time in direct patient care, and had ≥2 y of experience in their profession. The survey included a discrete choice experiment (DCE) in which HCPs selected preferred options from different hypothetical vaccine profiles with systematic variation in the levels of five attributes. Relative attribute importance was quantified. Among 548 HCP respondents, the median age was 43.2 y, and the majority were male (57.9%) and practiced in urban areas (69.7%). DCE results showed that attributes with the greatest impact on HCP decision-making were 1) immune response for the shared serotypes covered by PCV13 (31.4%), 2) percent of invasive pneumococcal disease (IPD) covered by vaccine serotypes (21.3%), 3) acute otitis media (AOM) label indication (20.3%), 4) effectiveness against serotype 3 (17.6%), and 5) number of serotypes in the vaccine (9.5%). Among US HCPs, the most important attribute of PCVs was comparability of immune response for PCV13 shared serotypes, while the number of serotypes was least important. Findings suggest new PCVs eliciting high immune responses for serotypes that contribute substantially to IPD burden and maintaining immunogenicity against serotypes in existing PCVs are preferred by HCPs.

State of pneumococcal vaccine immunity

Like the other invasive encapsulated bacteria, Streptococcus pneumoniae is also covered with a polysaccharide structure. Infants and elderly are most vulnerable to the invasive and noninvasive diseases caused by S. pneumoniae. Although antibodies against polysaccharide capsule are efficient in eliminating S. pneumoniae, the T cell independent nature of the immune response against polysaccharide vaccines renders them weakly antigenic. The introduction of protein conjugated capsular polysaccharide vaccines helped overcome the weak immunogenicity of pneumococcal polysaccharides and decreased the incidence of pneumococcal diseases, especially in pediatric population. Conjugate vaccines elicit T cell dependent response which involve the interaction of specialized CD4+ T cells, called follicular helper T cells (Tfh) with germinal center B cells in secondary lymphoid organs. Despite their improved immunogenicity, conjugate vaccines still need to be administered three to four times in infants during the first 15 month of their life because they mount poor Tfh response. Recent studies revealed fundamental differences in the generation of Tfh cells between neonates and adults. As the portfolio of pneumococcal conjugate vaccines continues to increase, better understanding of the mechanisms of antibody development in different age groups will help in the development of pneumococcal vaccines tailored for different ages.

Quantitation and characterization of serotype 6A activation for pneumococcal conjugate vaccine by cryo-EM and SEC methods

Pneumococcal conjugate vaccines (PCV) typically consist of capsular polysaccharides from different S. pneumoniae serotypes which are covalently attached to carrier protein. A well-established process to manufacture PCV is through activating polysaccharide by oxidation of vicinal diols to aldehydes, followed by protein conjugation via reductive amination. Polysaccharide activation is a crucial step that affects vaccine product critical attributes including conjugate size and structure. Therefore, it is highly desired to have robust analytical methods to well characterize this activation process. In this study, using pneumococcal serotype 6A as the model, we present two complimentary analytical methods for characterization of activated polysaccharide. First, a size exclusion chromatography (SEC) method was developed for quantitative measurement of polysaccharide activation levels. This SEC method demonstrated good assay characteristics on accuracy, precision and linearity. Second, a gold nanoparticle labeled cryo-electron microscopy (Cryo-EM) technique was developed to visualize activation site distribution along polysaccharide chain and provide information on activation heterogeneity. These two complimentary methods can be utilized to control polysaccharide activation process and ensure consistent delivery of conjugate vaccine products.

Chemical Synthesis of Truncated Capsular Oligosaccharide of Serotypes 6C and 6D of Streptococcus pneumoniae with Their Immunological Studies

Serotypes 6C and 6D of Streptococcus pneumoniae are two major variants that cause invasive pneumococcal disease (IPD) in serogroup 6 alongside serotypes 6A and 6B. Since the introduction of the pneumococcal conjugate vaccines PCV7 and PCV13, the number of cases of IPD caused by pneumococcus in children and the elderly population has greatly decreased. However, with the widespread use of vaccines, a replacement effect has recently been observed among different serotypes and lowered the effectiveness of the vaccines. To investigate protection against the original serotypes and to explore protection against variants and replacement serotypes, we created a library of oligosaccharide fragments derived from the repeating units of the capsular polysaccharides of serotypes 6A, 6B, 6C, and 6D through chemical synthesis. The library includes nine pseudosaccharides with or without exposed terminal phosphate groups and four pseudotetrasaccharides bridged by phosphate groups. Six carbohydrate antigens related to 6C and 6D were prepared as glycoprotein vaccines for immunogenicity studies. Two 6A and two 6B glycoconjugate vaccines from previous studies were included in immunogenicity studies. We found that the conjugates containing four phosphate-bridged pseudotetrasaccharides were able to induce good immune antibodies and cross-immunogenicity by showing superior activity and broad cross-protective activity in OPKA bactericidal experiments.

Orbital complications of pediatric acute rhinosinusitis in the pneumococcal conjugate vaccine era

OBJECTIVES

To evaluate the impact of the pneumococcal conjugate vaccines (PCVs) introduction on the orbital complications of acute rhino-sinusitis (OC-ARS).

METHODS

A retrospective cohort study of all pediatric patients with OC-ARS during the period 2002-2019. Data included clinical, demographic, laboratory, and microbiology findings. Patients were divided into three groups: before PCV7 introduction (group 1), after PCV7 and before PCV13 (group 2), and after PCV13 (group 3).

RESULTS

Of 265 enrolled patients, 117, 39, and 109 were assigned to groups 1, 2, and 3. During the study period, a significant decrease was recorded in the percentages of patients in Chandler classification severity category 1, with an increase in patients in category 3 (P = 0.011). The yearly incidence of OC-ARS decreased from 12.64 cases per 100,000 population in 2002 to 5.56 per 100,000 in 2008, and 2.99 per 100,000 in 2019 (P < 0.001). Patients aged 0-4 years showed a dramatic decrease from 29 cases per 100,000 population in 2002 to 4.27 per 100,000 in 2019 (P < 0.001). The pathogens retrieved from all cultures performed were Streptococcus pneumoniae (32.5%), non-typeable Haemophilus influenzae (27.5%), Streptococcus Species, (12.5%), and Staphylococcus aureus (20%), with no changes in distribution during the study periods. Surgery was performed in 28 (10.6%) patients.

CONCLUSIONS

A significant decrease was seen in the overall incidence of OC-ARS, mainly attributable to the decrease in patients aged 0-4 years. An increase was recorded in the severity of the disease following PCVs introduction.

Incidence of pneumococcal disease in children ≤48 months old in the United States: 1998-2019

BACKGROUND

Pneumococcal disease (PD) is a major cause of morbidity and mortality among children, particularly in the youngest age groups. This study aimed to assess the incidence of PD over time by age group in young children with commercial or Medicaid coverage in the US.

METHODS

Episodes of invasive pneumococcal disease (IPD), all-cause pneumonia (ACP), and acute otitis media (AOM) were identified in the MarketScan® Commercial and Medicaid claims databases using diagnosis codes among children aged ≤ 48 months with confirmed date of birth (DoB), at any time during the study period (1998-2019). DoB was assigned using diagnosis codes for birth or delivery using the child's or mother's medical claims to ensure accurate age determination. Annual incidence rates (IRs) were calculated as number of disease episodes/100,000 person-years (PY) for IPD and ACP and episodes/1,000 PY for AOM, for children aged 0-6, 7-12, 12-24, and 25-48 months.

RESULTS

Annual IPD IRs declined from 53 to 7 episodes/100,000 PY between 1998 and 2019 in commercially-insured and 58 to 9 episodes/100,000 PY between 2001 and 2019 in Medicaid-insured children. Annual ACP IRs declined from 5,600 to 3,952 episodes/100,000 PY, and from 6,706 to 4,521 episodes/100,000 PY, respectively, over these periods. In both populations, children aged 0-6 months had the highest incidence of IPD and inpatient ACP. Annual AOM IRs declined from 1,177 to 738 episodes/1,000 PY (commercially-insured) and 633 to 624 episodes/1,000 PY (Medicaid-insured), over these periods. IRs were higher in rural vs. urban areas for all disease manifestations.

CONCLUSIONS

Incidence rates of IPD, ACP, and AOM decreased in children with commercial insurance and Medicaid coverage from 1998 to 2019. However, burden of disease remained substantial, with higher annual IRs for IPD and ACP for Medicaid-insured vs. commercially-insured children. IPD and inpatient ACP were most common in the youngest children 0-6 months old, followed by the 7-12-month age group.

Monitoring Over a Decade in the Serotype Prevalence of Streptococcus pneumoniae in Iran: A Systematic Review and Meta-analysis

BACKGROUND

There is no comprehensive information about the circulating serotypes of Streptococcus pneumoniae in Iran in recent years. This study aimed to summarize information about the changes over a decade in the serotype prevalence of S. pneumoniae in Iran.

METHODS

We performed a comprehensive search in PubMed/Medline, Web of Science, Science Direct, and the Iranian Database, such as Magiran and SID, from January 2011 to February 2023. The systematic process, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), was carried out by two researchers who were both independent and calibrated. Statistical analyses were carried out using Comprehensive Meta-Analysis software. Identifying and measuring heterogeneity were done using I2 and the chi-square test. Finally, Begg's rank correlation test was used in combination with a funnel plot to evaluate any possible publication bias.

RESULTS

The search returned 16 relevant results, with a total of 1575 isolates. Of those studies, eight studies reported the distribution of S. pneumoniae serotypes among patients, three studies among healthy individuals, and five studies among both groups. As the meta-analysis revealed, the most common serotypes were 23F (n = 299, 14.1% [95% CI: 9.7-19.9]; I2 = 84.3%; P<0.001 for heterogeneity), 19F (n = 221, 13.4% [95% CI: 9.9-17.9; I2 = 76.7%; P<0.001 for heterogeneity]), and 19A (n = 102, 8.7% [95% CI: 6.5-11.7; I2 = 54.3%; P<0.001 for heterogeneity]). Moreover, Begg's test (P = 0.160, 0.173, and 0.176 for 23F, 19F, and 19A, respectively) showed no evidence of publication bias.

CONCLUSION

Based on our pooled results, the majority of the serotypes of pneumococci in the Iranian population were 23F, 19F, and 19A, respectively, over the last decade. The findings can be valuable in selecting effective pneumococcal vaccine candidates and targeted antibiotics in Iranian patients.

Safety and immunogenicity of a 15-valent pneumococcal conjugate vaccine in Japanese healthy infants: A Phase I study (V114-028)

This Phase I study evaluated the safety, tolerability, and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine (PCV), via subcutaneous (SC) or intramuscular (IM) administration, in healthy Japanese infants 3 months of age. A total of 133 participants were randomized to receive four doses (3 + 1 regimen) of V114-SC (n = 44), V114-IM (n = 45), or 13-valent PCV (PCV13)-SC (n = 44) at 3, 4, 5, and 12-15 months of age. Diphtheria, tetanus, and pertussis-inactivated poliovirus (DTaP-IPV) vaccine was administered concomitantly at all vaccination visits. The primary objective was to assess the safety and tolerability of V114-SC and V114-IM. Secondary objectives were to assess the immunogenicity of PCV and DTaP-IPV at 1-month post-dose 3 (PD3). On days 1-14 following each vaccination, the proportions of participants with systemic adverse events (AEs) were comparable across interventions, whereas injection-site AEs were higher with V114-SC (100.0%) and PCV13-SC (100.0%) than with V114-IM (88.9%). Most AEs were mild or moderate in severity and no vaccine-related serious AEs or deaths were reported. Serotype-specific immunoglobulin G (IgG) response rates at 1-month PD3 were comparable across groups for most shared serotypes between V114 and PCV13. For additional V114 serotypes 22F and 33F, IgG response rates were higher with V114-SC and V114-IM than with PCV13-SC. DTaP-IPV antibody response rates at 1-month PD3 for V114-SC and V114-IM were comparable with PCV13-SC. Findings suggest that vaccination with V114-SC or V114-IM in healthy Japanese infants is generally well tolerated and immunogenic.

Prediction of post-PCV13 pneumococcal evolution using invasive disease data enhanced by inverse-invasiveness weighting

Background

After introduction of pneumococcal conjugate vaccines (PCVs), serotype replacement occurred in the population of Streptococcus pneumoniae. Predicting which pneumococcal clones and serotypes will become more common in carriage after vaccination can enhance vaccine design and public health interventions, while also improving our understanding of pneumococcal evolution. We sought to use invasive disease data to assess how well negative frequency-dependent selection (NFDS) models could explain pneumococcal carriage population evolution in the post-PCV13 epoch by weighting invasive data to approximate strain proportions in the carriage population.

Methods

Invasive pneumococcal isolates were collected and sequenced during 1998-2018 by the Active Bacterial Core surveillance (ABCs) from the Centers for Disease Control and Prevention (CDC). To predict the post-PCV13 population dynamics in the carriage population using a NFDS model, all genomic data were processed under a bioinformatic pipeline of assembly, annotation, and pangenome analysis to define genetically similar sequence clusters (i.e., strains) and a set of accessory genes present in 5% to 95% of the isolates. The NFDS model predicted the strain proportion by calculating the post-vaccine strain composition in the weighted invasive disease population that would best match pre-vaccine accessory gene frequencies. To overcome the biases of invasive disease data, serotype-specific inverse-invasiveness weights were defined as the ratio of the proportion of the serotype in the carriage data to the proportion in the invasive data, using data from 1998-2001 in the United States, before conjugate vaccine introduction. The weights were applied to adjust both the observed strain proportion and the accessory gene frequencies.

Results

Inverse-invasiveness weighting increased the correlation of accessory gene frequencies between invasive and carriage data with reduced residuals in linear or logit scale for pre-vaccine, post-PCV7, and post-PCV13. Similarly, weighting increased the correlation of accessory gene frequencies between different time periods in the invasive data. By weighting the invasive data, we were able to use the NFDS model to predict strain proportions in the carriage population in the post-PCV13 epoch, with the adjusted R-squared between predicted and observed strain proportions increasing from 0.176 to 0.544 after weighting.

Conclusions

The weighting system adjusted the invasive disease surveillance data to better represent the carriage population of S. pneumoniae. The NFDS mechanism predicted the strain proportions in the projected carriage population as estimated from the weighted invasive disease frequencies in the post-PCV13 epoch. Our methods enrich the value of genomic sequences from invasive disease surveillance, which is readily available, easy to collect, and of direct interest to public health.

Naturally-induced serum antibody levels in children to pneumococcal polysaccharide 15B that correlate with protection from nasopharyngeal colonization but anti-serotype 15B antibody has low functional cross-reactivity with serotype 15C

BACKGROUND

Serotypes 15B and 15C have been added to new different pneumococcal-conjugate vaccines (PCV20 and V116, respectively). We determined a serum anti-15B antibody level that would be a correlate of protection (COP) against nasopharyngeal colonization and assessed functional cross-reactivity against serotype 15B and 15C in children following natural immunization.

METHOD

IgG-antibody to serotype 15B polysaccharide was measured by ELISA in 341 sera from 6 to 36 month old children collected before, at the time of, and after pneumococcal colonization caused by serotypes 15B and 15C. 155 age-matched controls who had no detected colonization caused by serotype 15B or 15C strains were used as controls. A two-step method was used for construction of COP models: a generalized estimating equation followed by logistic-regression. Opsonophagocytic (OPA) assays assessed functional cross-reactivity between serotypes 15B and 15C.

RESULTS

The derived COP for prevention of colonization was 1.18 µg/ml for serotype 15B and 0.63 µg/ml for serotype 15C, with a predictive probability of 80 %. Antibody levels did not correlate with OPA titers. 30 % of child samples, with moderate to high amounts of ELISA-measured antibody, showed no OPA titer against either serotype 15B or 15C. For remaining samples, very low or no functional cross-reactivity between serotypes 15B and 15C was measured.

CONCLUSIONS

A COP for prevention of colonization in young children based on naturally-induced antibody levels was derived for serotypes 15B and 15C that differed. Antibody levels correlated poorly with OPA titers and low functional cross-reactivity between serotypes 15B and 15C in child sera was observed.

Genomic analysis of Streptococcus pneumoniae serogroup 20 isolates in Alberta, Canada from 1993-2019

In the province of Alberta, Canada, invasive disease caused by Streptococcus pneumoniae serogroup 20 (serotypes 20A/20B) has been increasing in incidence. Here, we characterize provincial invasive serogroup 20 isolates collected from 1993 to 2019 alongside invasive and non-invasive serogroup 20 isolates from the Global Pneumococcal Sequencing (GPS) Project collected from 1998 to 2015. Trends in clinical metadata and geographic location were evaluated, and serogroup 20 isolate genomes were subjected to molecular sequence typing, virulence and antimicrobial resistance factor mining, phylogenetic analysis and pangenome calculation. Two hundred and seventy-four serogroup 20 isolates from Alberta were sequenced, and analysed along with 95 GPS Project genomes. The majority of invasive Alberta serogroup 20 isolates were identified after 2007 in primarily middle-aged adults and typed predominantly as ST235, a sequence type that was rare among GPS Project isolates. Most Alberta isolates carried a full-length whaF capsular gene, suggestive of serotype 20B. All Alberta and GPS Project genomes carried molecular resistance determinants implicated in fluoroquinolone and macrolide resistance, with a few Alberta isolates exhibiting phenotypic resistance to azithromycin, clindamycin, erythromycin, tetracycline and trimethoprim-sulfamethoxazole, as well as non-susceptibility to tigecycline. All isolates carried multiple virulence factors including those involved in adherence, immune modulation and nutrient uptake, as well as exotoxins and exoenzymes. Phylogenetically, Alberta serogroup 20 isolates clustered with predominantly invasive GPS Project isolates from the USA, Israel, Brazil and Nepal. Overall, this study highlights the increasing incidence of invasive S. pneumoniae serogroup 20 disease in Alberta, Canada, and provides insights into the genetic and clinical characteristics of these isolates within a global context.

[Dose-response relationship between age and Streptococcus pneumoniae vaccination coverage in kindergarten children]

OBJECTIVES

To investigate the potential relationship between age and Streptococcus pneumoniae vaccination coverage in kindergarten children, and to provide a basis for guiding vaccination and developing new protein vaccines.

METHODS

The stratified cluster random sampling method was used to select 1 830 healthy children from six kindergartens in Shunde District, Foshan City, China, and nasopharyngeal swabs were collected for the isolation and identification of Streptococcus pneumoniae. The logistic regression model based on restricted cubic spline was used to analyze the dose-response relationship between age and Streptococcus pneumoniae vaccination coverage.

RESULTS

The rate of nasal Streptococcus pneumoniae carriage was 22.46% (411/1 830) among the kindergarten children, with the predominant serotypes of 6B, 19F, 15A, 23A, 34, and 23F. The coverage rates of 10-valent pneumococcal conjugate vaccine (PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13) were 53.0% and 57.9%, respectively, and there was a significant non-linear dose-response relationship between age and the coverage rates of PCV10 and PCV13 (P<0.05), with a higher coverage rate of PCV10 (88.0%) and PCV13 (91.1%) in the children aged 2 years. There was a significant non-linear dose-response relationship between age and the coverage rates of pilus islet 1 (PI-1) and pilus islet 2 (PI-2) (P<0.05), with a lower vaccination coverage rate for PI-1 (37.7%) and PI-2 (16.1%). The coverage rates of PI-1 (13.0%-58.5%) and PI-2 (6.0%-29.4%) were lower in all age groups. The virulence genes lytA (99.5%) and ply (99.0%) associated with candidate protein vaccines showed higher vaccination coverage rates.

CONCLUSIONS

There is a significant non-linear dose-response relationship between the age of kindergarten children and the coverage rates of PCV10 and PCV13 serotypes, and kindergarten children aged 2 years have a relatively high coverage rate of PCV. The high prevalence of the virulence genes lytA and ply shows that they are expected to become candidate virulence factors for the development of a new generation of recombinant protein vaccines.

C-Terminal Lysine Residue of Pneumococcal Triosephosphate Isomerase Contributes to Its Binding to Host Plasminogen

The main causative agent of pneumonia, Streptococcus pneumoniae, is also responsible for invasive diseases. S. pneumoniae recruits human plasminogen for the invasion and colonization of host tissues. We previously discovered that S. pneumoniae triosephosphate isomerase (TpiA), an enzyme involved in intracellular metabolism that is essential for survival, is released extracellularly to bind human plasminogen and facilitate its activation. Epsilon-aminocaproic acid, a lysine analogue, inhibits this binding, suggesting that the lysine residues in TpiA are involved in plasminogen binding. In this study, we generated site-directed mutant recombinants in which the lysine residue in TpiA was replaced with alanine and analyzed their binding activities to human plasminogen. Results from blot analysis, enzyme-linked immunosorbent assay, and surface plasmon resonance assay revealed that the lysine residue at the C-terminus of TpiA is primarily involved in binding to human plasminogen. Furthermore, we found that TpiA binding to plasminogen through its C-terminal lysine residue was required for the promotion of plasmin activation by activating factors.

A Phase III, multicenter, randomized, double-blind, active comparator-controlled study to evaluate the safety, tolerability, and immunogenicity of V114 compared with PCV13 in healthy infants (PNEU-PED-EU-1)

BACKGROUND

V114 (15-valent pneumococcal conjugate vaccine [PCV]) contains all serotypes in 13-valent PCV (PCV13) and additional serotypes 22F and 33F. This study evaluated safety and immunogenicity of V114 compared with PCV13 in healthy infants, and concomitant administration with DTPa-HBV-IPV/Hib and rotavirus RV1 vaccines.

METHODS

V114 and PCV13 were administered in a 2+1 schedule at 2, 4, and 11-15 months of age. Adverse events (AEs) were collected on Days 1-14 following each vaccination. Serotype-specific anti-pneumococcal immunoglobulin G (IgG) was measured 30 days post-primary series (PPS), immediately prior to a toddler dose, and 30 days post-toddler dose (PTD). Primary objectives included non-inferiority of V114 to PCV13 for 13 shared serotypes and superiority of V114 to PCV13 for the two additional serotypes.

RESULTS

1184 healthy infants 42-90 days of age were randomized 1:1 to V114 (n = 591) or PCV13 (n = 593). Proportions of participants with solicited AEs and serious AEs were comparable between vaccination groups. V114 met pre-specified non-inferiority criteria for all 13 shared serotypes, based on the difference in proportions of participants with serotype-specific IgG concentrations ≥0.35 μg/mL (response rate; lower bound of two-sided 95% confidence interval [CI] >-10.0) and IgG geometric mean concentration (GMC) ratios (lower bound of two-sided 95% CI >0.5), and pre-specified superiority criteria for serotypes 22F and 33F (lower bound of two-sided 95% CI >10.0 for response rates and >2.0 for GMC ratios). Antibody responses to DTPa-HBV-IPV/Hib and RV1 vaccines met pre-specified non-inferiority criteria, based on antigen-specific response rates to DTPa-HBV-IPV/Hib and anti-rotavirus IgA geometric mean titers.

CONCLUSIONS

After a 2+1 schedule, V114 elicited non-inferior immune responses to 13 shared serotypes and superior responses to the two additional serotypes compared with PCV13, with comparable safety profile. These results support the routine use of V114 in infants.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04031846; EudraCT: 2018-003787-31.

Economic burden of acute otitis media, pneumonia, and invasive pneumococcal disease in children in the United States after the introduction of 13-valent pneumococcal conjugate vaccines during 2014-2018

BACKGROUND

Streptococcus pneumoniae remains a leading cause of morbidity, mortality, and healthcare resource utilization (HRU) among children. This study quantified HRU and cost of acute otitis media (AOM), pneumonia, and invasive pneumococcal disease (IPD).

METHODS

The IBM MarketScan® Commercial Claims and Encounters and Multi-State Medicaid databases from 2014 to 2018 were analyzed. Children with AOM, all-cause pneumonia, or IPD episodes were identified using diagnosis codes in inpatient and outpatient claims. HRU and costs were described for each condition in the commercial and Medicaid-insured populations. National estimates of the number of episodes and total cost ($US 2019 for each condition were extrapolated using data from the US Census Bureau.

RESULTS

Approximately 6.2 and 5.6 million AOM episodes were identified in commercial and Medicaid-insured children, respectively, during the study period. Mean cost per AOM episode was $329 (SD $1505) for commercial and $184 (SD $1524) for Medicaid-insured children. A total of 619,876 and 531,095 all-cause pneumonia cases were identified among commercial and Medicaid-insured children, respectively. Mean cost per all-cause pneumonia episode was $2304 (SD $32,309) in the commercial and $1682 (SD $19,282) in the Medicaid-insured population. A total of 858 and 1130 IPD episodes were identified among commercial and Medicaid-insured children, respectively. Mean cost per IPD episode was $53,213 (SD $159,904) for commercial and $23,482 (SD $86,209) for the Medicaid-insured population. Nationally, there were over 15.8 million cases of AOM annually, with total estimated cost of $4.3 billion, over 1.5 million cases of pneumonia annually, with total cost of $3.6 billion, and about 2200 IPD episodes annually, for a cost of $98 million.

CONCLUSIONS

The economic burden of AOM, pneumonia, and IPD among US children remains substantial. IPD and its manifestations were associated with higher HRU and costs per episode, compared to AOM and all-cause pneumonia. However, owing to their higher frequencies, AOM and all-cause pneumonia were the main contributors to the economic burden of pneumococcal disease nationally. Additional interventions, such as the development of pneumococcal conjugate vaccinees with sustained protection of existing vaccine type serotypes as well as broader inclusion of additional serotypes, are necessary to further reduce the burden of disease caused by these manifestations.

Twenty-Five Year Trend Change in the Etiology of Pediatric Invasive Bacterial Infections in Korea, 1996-2020

BACKGROUND

The coronavirus disease-2019 (COVID-19) pandemic has contributed to the change in the epidemiology of many infectious diseases. This study aimed to establish the pre-pandemic epidemiology of pediatric invasive bacterial infection (IBI).

METHODS

A retrospective multicenter-based surveillance for pediatric IBIs has been maintained from 1996 to 2020 in Korea. IBIs caused by eight bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pyogenes, Listeria monocytogenes, and Salmonella species) in immunocompetent children > 3 months of age were collected at 29 centers. The annual trend in the proportion of IBIs by each pathogen was analyzed.

RESULTS

A total of 2,195 episodes were identified during the 25-year period between 1996 and 2020. S. pneumoniae (42.4%), S. aureus (22.1%), and Salmonella species (21.0%) were common in children 3 to 59 months of age. In children ≥ 5 years of age, S. aureus (58.1%), followed by Salmonella species (14.8%) and S. pneumoniae (12.2%) were common. Excluding the year 2020, there was a trend toward a decrease in the relative proportions of S. pneumoniae (r_s = -0.430, P = 0.036), H. influenzae (r_s = -0.922, P < 0.001), while trend toward an increase in the relative proportion of S. aureus (r_s = 0.850, P < 0.001), S. agalactiae (r_s = 0.615, P = 0.001), and S. pyogenes (r_s = 0.554, P = 0.005).

CONCLUSION

In the proportion of IBIs over a 24-year period between 1996 and 2019, we observed a decreasing trend for S. pneumoniae and H. influenzae and an increasing trend for S. aureus, S. agalactiae, and S. pyogenes in children > 3 months of age. These findings can be used as the baseline data to navigate the trend in the epidemiology of pediatric IBI in the post COVID-19 era.

Increase in prevalence of Streptococcus pneumoniae serogroup 24 in children upon introducing 13-valent pneumococcal conjugate vaccine in Japan

After introducing the 13-valent pneumococcal conjugate vaccine (PCV13) for children, a change in the prevalence of different Streptococcus pneumoniae serotypes that cause invasive pneumococcal diseases (IPDs) has been observed. The prevalence of vaccine serotypes has decreased and that of non-vaccine serotypes has increased. Currently, serogroup 24 has become one of the major non-vaccine serotypes causing IPDs in children in Japan. The aim of this study was to characterize clinical and genomic features of S. pneumoniae serogroup 24 strains isolated from sterile body sites in Japanese children. Serotyping, multi-locus sequence typing and genomic analysis of capsular polysaccharides of 61 strains of serogroup 24 were performed from 2015 to 2021. Among the 61 strains, 36, 23 and two belonged to serotypes 24F, 24B and 24C, respectively. The 24F sequence type (ST) 2572 and 24B ST 2572 were the major serotypes and sequence types observed from 2015 to 2019. By contrast, 24F ST 162 and 24B ST 2754 were the two major serotypes and sequence types observed after 2020. Two strains of serotype 24C were detected for the first time in Japan. Sequence analysis of the abpA gene, which plays a role in the synthesis of capsular polysaccharides in S. pneumoniae , was performed to distinguish different strains of serogroup 24. After the introduction of PCV13 in Japan, serogroup 24 has become one of the most prevalent non-vaccine serotypes causing IPDs in children. This serogroup has not been targeted in the next-generation pneumococcal conjugate vaccines. Therefore, monitoring of S. pneumoniae serogroup 24 that causes IPDs in children is essential.

Cost-Effectiveness Analysis of Routine Use of 15-Valent Pneumococcal Conjugate Vaccine in the US Pediatric Population

This study evaluated the clinical and economic impact of routine pediatric vaccination with the 15-valent pneumococcal conjugate vaccine (PCV15, V114) compared with the 13-valent PCV (PCV13) from a societal perspective in the United States (US). A Markov decision-analytic model was constructed to estimate the outcomes for the entire US population over a 100-year time horizon. The model estimated the impact of V114 versus PCV13 on pneumococcal disease (PD) incidence, post meningitis sequalae, and deaths, taking herd immunity effects into account. V114 effectiveness was extrapolated from the observed PCV13 data and PCV7 clinical trials. Costs (2021$) included vaccine acquisition and administration costs, direct medical costs for PD treatment, direct non-medical costs, and indirect costs, and were discounted at 3% per year. In the base case, V114 prevented 185,711 additional invasive pneumococcal disease, 987,727 all-cause pneumonia, and 11.2 million pneumococcal acute otitis media cases, compared with PCV13. This led to expected gains of 90,026 life years and 96,056 quality-adjusted life years with a total saving of $10.8 billion. Sensitivity analysis showed consistent results over plausible values of key model inputs and assumptions. The findings suggest that V114 is a cost-saving option compared to PCV13 in the routine pediatric vaccination program.

A cost-effectiveness analysis of pneumococcal conjugate vaccines in infants and herd protection in older adults in Colombia

BACKGROUND

Pneumococcal diseases have a clinical and economic impact on the population. Until this year, a 10-valent pneumococcal vaccine (PCV10) used to be applied in Colombia, which does not contain serotypes 19A, 3, and 6A, the most prevalent in the country. Therefore, we aimed to assess the cost-effectiveness of the shift to the 13-valent pneumococcal vaccine (PCV13).

RESEARCH DESIGN AND METHODS

A decision model was used for newborns in Colombia between 2022-2025 and adults over 65 years. The time horizon was life expectancy. Outcomes are Invasive Pneumococcal Diseases (IPD), Community-Acquired Pneumonia (CAP), Acute Otitis Media (AOM), their sequelae, Life Gained Years (LYGs), and herd effect in older adults.

RESULTS

PCV10 covers 4.27% of serotypes in the country, while PCV13 covers 64.4%. PCV13 would avoid in children 796 cases of IPD, 19,365 of CAP, 1,399 deaths, and generate 44,204 additional LYGs, as well as 9,101 cases of AOM, 13 cases of neuromotor disability and 428 cochlear implants versus PCV10. In older adults, PCV13 would avoid 993 cases of IPD and 17,245 of CAP, versus PCV10. PCV13 saves $51.4 million. The decision model shows robustness in the sensitivity analysis.

CONCLUSION

PCV13 is a cost-saving strategy versus PCV10 to avoid pneumococcal diseases.

Health and economic burden associated with 15-valent pneumococcal conjugate vaccine serotypes in Korea and Hong Kong

Use of pneumococcal conjugate vaccines (PCVs) has greatly reduced the incidence of invasive pneumococcal disease (IPD). V114 (VAXNEUVANCE™, Merck Sharp & Dohme Corp. a subsidiary of Merck & Co. Inc. Kenilworth, NJ, USA) is a 15-valent PCV currently approved in adults in the United States, containing the 13 serotypes in licensed PCV13 and 2 additional serotypes (22F and 33F) which are important contributors to residual pneumococcal disease. This study quantified the health and economic burden of IPD attributable to V114 serotypes in hypothetical birth cohorts from Korea and Hong Kong. A Markov model was used to estimate the case numbers and costs of IPD in unvaccinated birth cohorts over 20 years. The model was applied to 3 scenarios in Korea (pre-PCV7, pre-PCV13, and post-PCV13) and to 2 scenarios in Hong Kong (pre-PCV7 and post-PCV13). For Korea, the model predicted 62, 26, and 8 IPD cases attributable to V114 serotypes in the pre-PCV7, pre-PCV13, and post-PCV13 scenarios, respectively. Costs of V114-type IPD fell from $1.691 million pre-PCV7 to $.212 million post-PCV13. For Hong Kong, the model estimated 62 V114-associated IPD cases in the pre-PCV7 scenario and 46 in the post-PCV13 scenario. Costs attributed to all V114 serotypes were $2.322 million and $1.726 million in the pre-PCV7 and post-PCV13 periods, respectively. Vaccine-type serotypes are predicted to cause continuing morbidity and cost in Korea (19A) and Hong Kong (3 and 19A). New pediatric pneumococcal vaccines must continue to protect against serotypes in licensed vaccines to maintain disease reduction, while extending coverage to non-vaccine serotypes.

Predicting vaccine effectiveness against invasive pneumococcal disease in children using immunogenicity data

The strength of the immune response, as measured by antibody concentrations, varies between pneumococcal conjugate vaccines (PCVs). Linking immunogenicity and effectiveness is necessary to assess whether changes in immune response from currently recommended PCVs to next-generation vaccines could impact effectiveness. Simulated reverse cumulative distribution curves were generated using published serotype-specific IgG concentrations with placebo or PCV7. This was combined with the published estimates of serotype-specific vaccine effectiveness of PCV7 against invasive pneumococcal disease to estimate the protective antibody concentration for each serotype in PCV7. Then, based on the published serotype-specific IgG concentrations in PCV13 recipients, reverse cumulative distribution curves were generated for the serotypes shared between PCV13 and PCV7. These estimated protective antibody concentration values were then used to predict the vaccine effectiveness of PCV13. The results were compared to published aggregate values for vaccine effectiveness. The aggregate median predicted vaccine effectiveness values were similar to previously reported observed values for the United Kingdom (93% versus 90%), Australia (71% versus 70%), and Germany (91% versus 90%). These results demonstrate that IgG concentrations of next-generation PCVs can be used to generate reliable estimates of vaccine effectiveness for serotypes shared with established PCVs.

A phase III, multicenter, randomized, double-blind, active comparator-controlled study to evaluate the safety, tolerability, and immunogenicity of catch-up vaccination regimens of V114, a 15-valent pneumococcal conjugate vaccine, in healthy infants, children, and adolescents (PNEU-PLAN)

BACKGROUND

Despite widespread use of pneumococcal conjugate vaccines (PCVs) in children, morbidity and mortality caused by pneumococcal disease (PD) remain high. In addition, many children do not complete their PCV course on schedule. V114 is a 15-valent PCV that contains two epidemiologically important serotypes, 22F and 33F, in addition to the 13 serotypes present in PCV13, the licensed 13-valent PCV.

METHODS

This phase III descriptive study evaluated safety and immunogenicity of catch-up vaccination with V114 or PCV13 in healthy children 7 months-17 years of age who were either pneumococcal vaccine-naïve or previously immunized with lower valency PCVs (NCT03885934). Overall, 606 healthy children were randomized to receive V114 (n = 303) or PCV13 (n = 303) via age-appropriate catch-up vaccination schedules in three age cohorts (7-11 months, 12-23 months, or 2-17 years).

RESULTS

Similar proportions of children 7-11 months and 2-17 years of age reported adverse events (AEs) in the V114 and PCV13 groups. A numerically greater proportion of children 12-23 months of age reported AEs in the V114 group (79.0%) than the PCV13 group (59.4%). The proportions of children who reported serious AEs varied between different age cohorts but were generally comparable between vaccination groups. No vaccine-related serious AEs were reported, and no deaths occurred. At 30 days after the last PCV dose, serotype-specific immunoglobulin G geometric mean concentrations were comparable between vaccination groups for the 13 shared serotypes and higher in the V114 group for 22F and 33F.

CONCLUSIONS

Catch-up vaccination with V114 in healthy individuals 7 months-17 years of age was generally well tolerated and immunogenic for all 15 serotypes, including those not contained in PCV13, regardless of prior pneumococcal vaccination. These results support V114 catch-up vaccination in children with incomplete or no PCV immunization per the recommended schedule.

Invasive pneumococcal disease and long-term outcomes in children: A 20-year population cohort study

BACKGROUND

Although vaccination against Streptococcus pneumoniae infections (such as invasive pneumococcal disease (IPD)) are available, challenges remain in prevention efforts. Moreover, downstream sequelae in children is relatively unknown. Thus, we aimed to evaluate short and long-term health outcomes among children with IPD.

METHODS

Analysis of Streptococcus pneumoniae positive isolates from sterile body sites in children (0-17 years) in Alberta (Canada) from 1999 to 2019 was performed retrospectively (n=888). Cases were age and sex-matched to hospitalized population controls. Linkage to administrative health datasets was done to determine comorbidities and healthcare related outcomes. Cox proportional hazards were used to assess differences in time to mortality and hospitalisation between cases and controls in short (<30-day), intermediate (30-90 day), long-term (>90-day) follow-up.

FINDINGS

Proportionally more deaths occurred in cases (4.8 deaths/1000 person-years (PY)) than controls (2.7 deaths/1000 PY), leading to a significant adjusted hazard ratio (aHR) of 1.80 (95% CI 1.22-2.64). This increased risk of death was influenced primarily by short-term mortality (319 vs 36 deaths/1000 PY in cases vs controls respectively, aHR 8.78 [95% CI 3.33-23.18]), as no differences were seen in intermediate (14 vs 7 deaths/1000 PY; aHR 2.03, 95% CI 0.41-10.04) or long-term time intervals (2.4 vs 2.3 deaths/1000 PY, aHR 1.03, 95% CI 0.63-1.69).

INTERPRETATION

IPD continues to negatively impact survival in children despite vaccination. Although long-term impact on mortality and hospitalisations may not be substantial, the immediate effects of IPD are significant.

FUNDING

This work was supported by grants-in-aid from Pfizer Canada and Wyeth Canada Inc all to GJT.

Controlled Human Infection Models To Accelerate Vaccine Development

The timelines for developing vaccines against infectious diseases are lengthy, and often vaccines that reach the stage of large phase 3 field trials fail to provide the desired level of protective efficacy. The application of controlled human challenge models of infection and disease at the appropriate stages of development could accelerate development of candidate vaccines and, in fact, has done so successfully in some limited cases. Human challenge models could potentially be used to gather critical information on pathogenesis, inform strain selection for vaccines, explore cross-protective immunity, identify immune correlates of protection and mechanisms of protection induced by infection or evoked by candidate vaccines, guide decisions on appropriate trial endpoints, and evaluate vaccine efficacy. We prepared this report to motivate fellow scientists to exploit the potential capacity of controlled human challenge experiments to advance vaccine development. In this review, we considered available challenge models for 17 infectious diseases in the context of the public health importance of each disease, the diversity and pathogenesis of the causative organisms, the vaccine candidates under development, and each model's capacity to evaluate them and identify correlates of protective immunity. Our broad assessment indicated that human challenge models have not yet reached their full potential to support the development of vaccines against infectious diseases. On the basis of our review, however, we believe that describing an ideal challenge model is possible, as is further developing existing and future challenge models.

Incidence of invasive pneumococcal disease in children with commercial insurance or Medicaid coverage in the United States before and after the introduction of 7- and 13-valent pneumococcal conjugate vaccines during 1998-2018

Background

Invasive pneumococcal disease (IPD) is a major cause of pediatric morbidity and mortality. Pneumococcal conjugate vaccines (PCVs) were introduced in the US in 2000 (PCV7) and 2010 (PCV13). This study estimated the annual incidence rates (IRs) and time trends of IPD to quantify the burden of disease in children before and after the introduction of PCV7 and PCV13 in the US.

Methods

IPD episodes were identified in the IBM MarketScan Commercial and Medicaid Databases using claims with International Classification of Diseases 9/10^th Revision, Clinical Modification codes. Annual IRs were calculated as the number of IPD episodes/100,000 person-years (PYs) for children < 18 years and by age group (< 2, 2–4, and 5–17 years). National estimates of annual IPD IRs were extrapolated using Census Bureau data. Interrupted time series (ITS) analyses were conducted to assess immediate and gradual changes in IPD IRs before and after introduction of PCV7 and PCV13.

Results

In commercially insured children, IPD IRs decreased from 9.4 to 2.8 episodes/100,000 PY between the pre-PCV7 (1998–1999) and late PCV13 period (2014–2018) overall, and from 65.6 to 11.6 episodes/100,000 PY in children < 2 years. In the Medicaid population, IPD IRs decreased from 11.3 to 4.2 episodes/100,000 PY between the early PCV7 (2001–2005) and late PCV13 period overall, and from 42.6 to 12.8 episodes/100,000 PY in children < 2 years. The trends of IRs for meningitis, bacteremia, and bacteremic pneumonia followed the patterns of overall IPD episodes. The ITS analyses indicated significant decreases in the early PCV7 period, increases in the late PCV7 and decreases in the early PCV13 period in commercially insured children overall. However, increases were also observed in the late PCV13 period in children < 2 years. The percentage of cases with underlying risk factors increased in both populations.

Conclusions

IRs of IPD decreased from 1998 to 2018, following introduction of PCV7 and PCV13, with larger declines during the early PCV7 and early PCV13 periods, and among younger children. However, the residual burden of IPD remains substantial. The impact of future PCVs on IPD IRs will depend on the proportion of vaccine-type serotypes and vaccine effectiveness in children with underlying conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-14051-6.

The Economic Burden of Pneumococcal Disease in Children: A Population-Based Investigation in the Veneto Region of Italy

Despite widespread childhood immunization programs, pneumococcal disease (PD) continues to be associated with significant clinical and economic burden worldwide. This retrospective study assessed the PD-related economic burden in children from the Veneto region of Italy following the introduction of a 13-valent pneumococcal conjugate vaccine (PCV13) to the Italian immunization schedule in 2010. Between 2010 and 2017, the annual incidences of pneumonia, acute otitis media (AOM), and invasive pneumococcal disease (IPD), as well as syndromic-disease-related episodes, declined. In our analysis of data from regional expenditure and healthcare resource utilization (HCRU) databases related to children < 15 years of age, we found that regional expenditures decreased between 2010 and 2017 for pneumonia (EUR 8.88 to EUR 3.59 million), AOM (EUR 3.78 to EUR 2.76 million), and IPD (EUR 1.40 to EUR 1.00 million). Despite reductions in PD-related expenditure following the introduction of PCV13, there continues to be an economic burden associated with PD in Veneto, Italy.

Predicting effectiveness of the V114 vaccine against invasive pneumococcal disease in children

BACKGROUND

The potential impact of new pneumococcal conjugate vaccines (PCVs) is assessed by using immune responses to predict their effectiveness against invasive pneumococcal disease (IPD). This analysis predicted the serotype-specific effectiveness against IPD of a new 15-valent PCV (V114) for the serotypes shared with a 13-valent PCV (PCV13), in a US pediatric population given a 3 + 1 dosing regimen.

METHODS

Beginning with the known serotype-specific antibody concentrations after vaccination with placebo, 7-valent PCV (PCV7) and PCV13, reverse cumulative distribution curves were used, along with published serotype-specific vaccine effectiveness of PCV7 and PCV13, to derive a protective antibody concentration (C_p) for each PCV13 serotype in V114. Serotype-specific effectiveness was predicted using the C_p estimates and the respective serotype-specific antibody concentrations of placebo and V114 recipients in recent pediatric clinical trials.

RESULTS

Predicted serotype-specific V114 effectiveness values ranged from 86% to 99% for PCV7 serotypes and from 59% to 97% for (non-PCV7) PCV13 serotypes.

CONCLUSIONS

V114 serotype-specific effectiveness against IPD in a US pediatric population was predicted to be largely comparable to that of PCV7 and PCV13 for shared serotypes, with models suggesting likelihood of high overall benefit gained from increased serotype 3 effectiveness, and additional protection against serotypes 22 F and 33 F.

Incidence of Hospitalisation and Emergency Department Visits for Pneumococcal Disease in Children, Adolescents, and Adults in Liguria, Italy: A Retrospective Analysis from 2012-2018

Streptococcus pneumoniae infection is responsible for significant morbidity and mortality, particularly in young children and older adults. The aim of this study was to investigate the incidence of hospitalisation and emergency department (ED) visits in relation to episodes of pneumococcal disease (PD) following the introduction of pneumococcal conjugate vaccines (PCVs) into the Liguria region of Italy. Between 2012 and 2018, episodes of all-cause pneumonia (80,152), pneumococcal-specific pneumonia (1254), unspecified pneumonia (66,293), acute otitis media (AOM; 17,040), and invasive PD (IPD; 1788) were identified from in-patient claims, ED and hospital discharge records, and the Liguria Chronic Condition Data Warehouse. In children < 15 years of age, pneumococcal pneumonia-related hospitalisations decreased from 35 to 13 per 100,000 person-years during the study period (p < 0.001); this decrease is potentially related to PCV use in children. All-cause pneumonia hospitalisations remained stable, whereas IPD hospitalisations increased and AOM hospitalisations decreased. In adults, hospitalisations for all-cause pneumonia increased from 5.00 to 7.50 per 1000 person-years (+50%; p < 0.001). Pneumococcal and unspecified pneumonia hospital admissions increased significantly during the study period, considerably affecting those ≥ 65 years of age. IPD hospitalisations varied across all age groups, but a significant change was not observed. Despite pneumococcal vaccination, substantial burden remains for PD in children and adults in Liguria, Italy.

Exploration of Streptococcus core genome to reveal druggable targets and novel therapeutics against S. pneumoniae

Streptococcus pneumoniae (S. pneumoniae), the major etiological agent of community-acquired pneumonia (CAP) contributes significantly to the global burden of infectious diseases which is getting resistant day by day. Nearly 30% of the S. pneumoniae genomes encode hypothetical proteins (HPs), and better understandings of these HPs in virulence and pathogenicity plausibly decipher new treatments. Some of the HPs are present across many Streptococcus species, systematic assessment of these unexplored HPs will disclose prospective drug targets. In this study, through a stringent bioinformatics analysis of the core genome and proteome of S. pneumoniae PCS8235, we identified and analyzed 28 HPs that are common in many Streptococcus species and might have a potential role in the virulence or pathogenesis of the bacteria. Functional annotations of the proteins were conducted based on the physicochemical properties, subcellular localization, virulence prediction, protein-protein interactions, and identification of essential genes, to find potentially druggable proteins among 28 HPs. The majority of the HPs are involved in bacterial transcription and translation. Besides, some of them were homologs of enzymes, binding proteins, transporters, and regulators. Protein-protein interactions revealed HP PCS8235_RS05845 made the highest interactions with other HPs and also has TRP structural motif along with virulent and pathogenic properties indicating it has critical cellular functions and might go under unconventional protein secretions. The second highest interacting protein HP PCS8235_RS02595 interacts with the Regulator of chromosomal segregation (RocS) which participates in chromosome segregation and nucleoid protection in S. pneumoniae. In this interacting network, 54% of protein members have virulent properties and 40% contain pathogenic properties. Among them, most of these proteins circulate in the cytoplasmic area and have hydrophilic properties. Finally, molecular docking and dynamics simulation demonstrated that the antimalarial drug Artenimol can act as a drug repurposing candidate against HP PCS8235_RS 04650 of S. pneumoniae. Hence, the present study could aid in drugs against S. pneumoniae.

Clinical manifestations and outcome of viral acute lower respiratory infection in hospitalised children in Myanmar

Background

Acute lower respiratory infection (ALRI) remains the leading cause of death in children worldwide, and viruses have been the major cause of ALRI. In Myanmar, ALRI is associated with high morbidity and mortality in children, and detailed information on ALRI is currently lacking.

Methods

This prospective study investigated the viral aetiologies, clinical manifestations, and outcomes of ALRI in hospitalised children aged 1 month to 12 years at the Yankin Children Hospital, Yangon, Myanmar from May 2017 to April 2019. The sample size was set to 300 patients for each year. Two nasopharyngeal swabs were obtained for the patients with suspected viral ALRI; one for rapid tests for influenza and respiratory syncytial virus (RSV), and the other for real-time PCR for the 16 ALRI-causing viruses. Pneumococcal colonization rates were also investigated using real-time PCR. Clinical information was extracted from the medical records, and enrolled patients were categorised by age and severity for comparison.

Results

Among the 5463 patients admitted with a diagnosis of ALRI, 570 (10.4%) were enrolled in this study. The median age of the patients was 8 months (interquartile range, 4–15 months). The most common symptoms were cough (93%) and difficulty in breathing (73%), while the most common signs of ALRI were tachypnoea (78%) and chest indrawing (67%). A total of 16 viruses were detected in 502 of 570 patients’ samples (88%), with RSV B (36%) and rhinovirus (28%) being the most commonly detected. Multiple viruses were detected in 221 of 570 samples (37%) collected from 570 patients. Severe ALRI was diagnosed in 107 of 570 patients (19%), and RSV B and human rhinovirus were commonly detected. The mortality rate was 5%; influenza virus A (29%) and RSV B (21%) were commonly detected, and stunting and lack of immunization were frequently observed in such cases. Additionally, 45% (259/570) of the patients had pneumococcal colonization.

Conclusions

Viral ALRI in hospitalised children with a median of 8 months has significant morbidity and mortality rates in Myanmar. RSV and rhinovirus were the most commonly detected from nasopharyngeal swabs, while influenza virus and RSV were the most frequently associated with fatal cases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07342-1.

Incidence and Estimated Vaccine Effectiveness Against Hospitalizations for All-Cause Pneumonia Among Older US Adults Who Were Vaccinated and Not Vaccinated With 13-Valent Pneumococcal Conjugate Vaccine

Importance

Following routine use of 13-valent pneumococcal conjugate vaccine (PCV13) in children in 2010, invasive pneumococcal disease rates have decreased substantially in children and adults. In 2014, the Advisory Committee for Immunization Practices recommended routine use of PCV13 among adults aged 65 years or older; previously only 23-valent pneumococcal polysaccharide vaccine (PPV23) was recommended.

Objective

To estimate the association between the incidence of hospitalized all-cause pneumonia and lower respiratory tract infections (LRTI) and PCV13 vaccination among older adults at Kaiser Permanente Northern California (KPNC).

Design, Setting, and Participants

This retrospective cohort study included adults at KPNC aged 65 years or older between July 1, 2015, and June 30, 2018, born after 1936 with no known history of PPV23 or PCV13 receipt before age 65. The study took place at an integrated health care system with an annual membership more than 4 million individuals, approximately 15% of whom are 65 years or older and broadly representative of the region. Data analysis took place from July 2018 to December 2021, and data collection took place from November 2016 to June 2018.

Exposures

PCV13 vaccination status was ascertained from the electronic medical record (EMR). Individuals were considered vaccinated 14 days following immunization.

Main Outcomes and Measures

First hospitalized all-cause pneumonia was identified in the EMR using primary/secondary discharge diagnosis International Classification of Diseases, Ninth Revision and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes. First hospitalized LRTI was identified using pneumonia codes and acute bronchitis codes. Relative risk (RR) of first pneumonia or LRTI hospitalization of individuals who were PCV13 vaccinated vs PCV13 unvaccinated was estimated using Poisson regressions adjusted for sex, race, ethnicity, age, influenza vaccine receipt, PPV23 receipt since age 65, pneumonia risk factors, health care use, and season. Vaccine effectiveness (VE) was estimated as (1-RR) × 100%.

Results

Of 192 061 adults, 107 957 (56%) were female and 139 024 (72%) were White individuals. PCV13 coverage increased from 0 in 2014 to 135 608 (76.9%) by 2018. There were 3488 individuals with 3766 pneumonia hospitalizations and 3846 individuals with 4173 LRTI hospitalizations. PCV13 was associated with an adjusted VE of 10.0% (95% CI, 2.4-17.0; P = .01) against hospitalized pneumonia and 9.4% (95% CI, 2.1-16.1; P = .01) against hospitalized LRTI.

Conclusions and Relevance

In the context of a robust pediatric PCV13 immunization program, PCV13 vaccination of adults aged 65 years or older was associated with significant reductions in hospitalizations for all-cause pneumonia and LRTI. Vaccinating older adults with PCVs may provide broader public health benefit against pneumonia hospitalizations.

A Rare Case of Pneumococcal Appendicitis in a Child

Appendicitis is the most common cause for abdominal surgery in children. It is usually caused by Escherichia coli and Streptococcus species and is generally polymicrobial. However, Streptococcus pneumoniae is a rare cause of appendicitis. We report a rare case of pneumococcal appendicitis in a 7-year-old child with no underlying conditions, in association with E. coli and group F β-hemolytic Streptococcus. The isolated pneumococcal strain was sensible to all tested antibiotics. The patient had a full recovery after surgery and antibiotics. This case emphasizes that S. pneumoniae can cause a variety of unusual infections like appendicitis, in patients with or without underlying conditions. Thus, even though being a rare entity, physicians should always be aware of S. pneumoniae as a possible causative agent.

The impact of pneumococcal conjugate vaccine on the prevalence and severity of hospitalizations for pneumonia in children

Pneumococcal conjugate vaccines (PCV) were introduced into the Israeli national immunization plan starting with the heptavalent PCV7 in 2009 and then PCV13 in the late 2010. The objective of this study was to determine the vaccines' impact on hospitalization rates for community-acquired pneumonia on the severity of the pneumonia episodes and upon pneumococcal serotype distribution. We retrospectively reviewed all children hospitalized in our institution with pneumonia, aged between 1 and 16 years, between the years 2006 and 2015. Demographic, clinical, and laboratory data between three time periods: pre-PCV, PCV7, and PCV13, were compared. During the study period, 1375 children were hospitalized with pneumonia. A gradual decline in hospitalization rates due to pneumonia was observed starting in 2006 in the pre-PCV period and continued until after the introduction of PCV13. A similar trend was observed in pneumonias with a culture positive for S. pneumoniae. Pleural effusion was observed in 24% of all pneumonias, and this percentage was stable throughout the study period. The average age at hospitalization increased during the study period, as did the average duration of hospital stay. Pneumococcal serotypes included in the vaccine were isolated less frequently during the study and non-vaccine serotypes tended to appear more frequently. Pediatric pneumonia hospitalization rates continued to decline since the introduction of PCV without increasing the frequency of complications. Pneumococcal serotype distribution shifted in parallel. Our findings confirm the efficacy of PCV and support the evidence to include more serotypes in the next generation of PCV.

Streptococcus pneumoniae Serotypes Associated with Death, South Africa, 2012-2018

The Streptococcus pneumoniae polysaccharide capsule plays a role in disease severity. We assessed the association of serotype with case-fatality ratio (CFR) in invasive pneumococcal disease (IPD) and meningitis in South Africa, 2012-2018 (vaccine era), using multivariable logistic regression by manual backward elimination. The most common serotypes causing IPD were 8 and 19A. In patients <15 years of age, serotypes associated with increased CFR in IPD, compared with serotype 8 and controlling for confounding factors, were 11A, 13, 19F, 15A, and 6A. None of these serotypes were associated with increased CFR in meningitis. Among IPD patients >15 years of age, serotype 15B/C was associated with increased CFR. Among meningitis patients of all ages, serotype 1 was associated with increased CFR. PCV13 serotypes 1, 3, 6A, 19A, and 19F should be monitored, and serotypes 8, 12F, 15A, and 15B/C should be considered for inclusion in vaccines to reduce deaths caused by S. pneumoniae.

Pneumococcal Vaccine Recommendations for Old-Age Home Indian Residents: A Literature Review

Advancing age is accompanied by decreased immunity, poor health, and physiological changes, which render the elderly population highly susceptible to infectious diseases. We aim to identify the guidelines for pneumococcal vaccines in old-age facilities in India. We performed an extensive review of Indian literature (indexed and non-indexed publications) from 2010 to 2020 using search strings “Pneumococcal vaccine AND Recommendations AND India,” “Pneumococcal vaccine AND Guidelines AND India,” followed by a hand search to identify the most updated versions of recommendations. We reviewed immunization guidelines recommended by nine medical associations and societies in India—Association of Physicians of India (API), Geriatric Society of India (GSI), Indian Society of Nephrology (ISN), Mass Gathering Advisory Board Consensus Recommendation, Indian Medical Association (IMA), Indian Chest Society and National College of Chest Physicians (ICS-NCCP), Research Society for Study of Diabetes in India (RSSDI), Indian Association of Occupational Health Guidelines for Working Adults (IAOH), and API guidelines for immunization during COVID19 pandemic. All bodies recommend pneumococcal vaccines, sequence and preference of which depend on factors such as age, underlying conditions, and immune status. Integration of society recommendations and their implementation into public and private vaccination programs are required to promote adult immunization.

Economic Burden of Pneumococcal Disease in Individuals Aged 15 Years and Older in the Liguria Region of Italy

Despite the availability of vaccines against Streptococcus pneumoniae, the global incidence and economic cost of pneumococcal disease (PD) among adults is still high. This retrospective cohort analysis estimated the cost of emergency department (ED) visits/hospitalizations associated with non-invasive pneumonia and invasive pneumococcal disease among individuals ≥15 years of age in the Liguria region of Italy during 2012–2018. Data from the Liguria Region Administrative Health Databases and the Ligurian Chronic Condition Data Warehouse were used, including hospital admission date, length of stay, discharge date, outpatient visits, and laboratory/imaging procedures. A ≥30-day gap between two events defined a new episode, and patients with ≥1 ED or inpatient claim for PD were identified. The total mean annual number of hospitalizations for PD was 13,450, costing ~€49 million per year. Pneumonia accounted for the majority of hospitalization costs. The median annual cost of hospitalization for all-cause pneumonia was €38,416,440 (per-capita cost: €26.78) and was €30,353,928 (per-capita cost: €20.88) for pneumococcal and unspecified pneumonia. The total number and associated costs of ED visits/hospitalizations generally increased over the study period. PD still incurs high economic costs in adults in the Liguria region of Italy.

Clarithromycin Inhibits Pneumolysin Production via Downregulation of ply Gene Transcription despite Autolysis Activation

Streptococcus pneumoniae, the most common cause of community-acquired pneumonia, causes severe invasive infections, including meningitis and bacteremia. The widespread use of macrolides has been reported to increase the prevalence of macrolide-resistant S. pneumoniae (MRSP), thereby leading to treatment failure in patients with pneumococcal pneumonia. However, previous studies have demonstrated that several macrolides and lincosamides have beneficial effects on MRSP infection since they inhibit the production and release of pneumolysin, a pneumococcal pore-forming toxin released during autolysis. In this regard, we previously demonstrated that the mechanisms underlying the inhibition of pneumolysin release by erythromycin involved both the transcriptional downregulation of the gene encoding pneumolysin and the impairment of autolysis in MRSP. Here, using a cell supernatant of the culture, we have shown that clarithromycin inhibits pneumolysin release in MRSP. However, contrary to previous observations in erythromycin-treated MRSP, clarithromycin upregulated the transcription of the pneumococcal autolysis-related lytA gene and enhanced autolysis, leading to the leakage of pneumococcal DNA. On the other hand, compared to erythromycin, clarithromycin significantly downregulated the gene encoding pneumolysin. In a mouse model of MRSP pneumonia, the administration of both clarithromycin and erythromycin significantly decreased the pneumolysin protein level in bronchoalveolar lavage fluid and improved lung injury and arterial oxygen saturation without affecting bacterial load. Collectively, these in vitro and in vivo data reinforce the benefits of macrolides on the clinical outcomes of patients with pneumococcal pneumonia.

IMPORTANCE Pneumolysin is a potent intracellular toxin possessing multiple functions that augment pneumococcal virulence. For over 10 years, sub-MICs of macrolides, including clarithromycin, have been recognized to decrease pneumolysin production and release from pneumococcal cells. However, this study indicates that macrolides significantly slowed pneumococcal growth, which may be related to decreased pneumolysin release recorded by previous studies. In this study, we demonstrated that clarithromycin decreases pneumolysin production through downregulation of ply gene transcription, regardless of its inhibitory activity against bacterial growth. Additionally, administration of clarithromycin resulted in the amelioration of lung injury in a mouse model of pneumonia induced by macrolide-resistant pneumococci. Therefore, therapeutic targeting of pneumolysin offers a good strategy to treat pneumococcal pneumonia.

Safety, tolerability, and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine, followed by sequential PPSV23 vaccination in healthy adults aged ≥50 years: A randomized phase III trial (PNEU-PATH)

BACKGROUND

Streptococcus pneumoniae causes pneumococcal disease, and older adults are at an increased risk. Sequential vaccination of 13-valent pneumococcal conjugate vaccine (PCV13) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for broad protection against pneumococcal disease in some countries.

METHODS

This phase III trial evaluated the safety, tolerability, and immunogenicity of sequential administration of either V114 (a 15-valent PCV containing serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F, and 33F) or PCV13, followed 12 months later by PPSV23, in healthy adults aged ≥50 years (NCT03480763). A total of 652 participants were randomized 1:1 to receive either V114 or PCV13, followed by PPSV23.

RESULTS

The most common solicited adverse events (AEs) following PCV vaccination included injection-site pain and fatigue. Higher proportions of participants with these events were observed in the V114 group following PCV; however, these differences were not clinically significant. Following PPSV23 vaccination, the most common solicited AEs were injection-site pain and injection-site swelling; the proportions of participants with these events were comparable between both groups. Incidence of serious AEs was low in both groups following PCV and PPSV23, and none were related to study vaccines. No deaths occurred during the study. Serum opsonophagocytic activity geometric mean titers and immunoglobulin G geometric mean concentrations were comparable between both groups for all 15 serotypes in V114 following PPSV23. Immune responses elicited by V114 persisted for at least 12 months. Immune responses at 30 days and 12 months post-vaccination with PCV were comparable between both groups for the 13 shared serotypes and higher in the V114 group for the V114-unique serotypes (22F and 33F).

CONCLUSION

Administration of V114 followed by PPSV23 was well tolerated and induced comparable antibody levels to PCV13 followed by PPSV23 in healthy adults aged ≥50 years.

Prevalence of Invasive Streptococcus pneumoniae Infections among Iranian Children: A Systematic Review and Meta-Analysis

Background:

Streptococcus pneumoniae is an important pathogen of children, mostly in developing countries. We aimed to investigate the prevalence of invasive S. pneumoniae among Iranian children using a systematic review and meta-analysis.

Methods:

A systematic search was carried out to identify papers published by Iranian authors in the Web of Science, PubMed, Scopus, and Google Scholar electronic databases from January of 2010 to December of 2017. Then, seven publications that met our inclusion criteria were selected for data extraction and analysis.

Results:

Totally, one study was multicenter, and six were single-center based studies. Meanwhile, all of the included studied performed among hospitalized patients. Seven studies reported the prevalence of invasive S. pneumoniae isolated from children, of these the pooled prevalence of S. pneumoniae was 2.5% (95% CI: 0.7%–9.1%).

Conclusion:

The overall prevalence of invasive S. pneumoniae infections among Iranian children is low (2.5%). However, further clinical studies are required to elucidate the burden of infections among Iranian children, especially in eastern regions.

The Burden of Invasive Bacterial Disease and the Impact of 10-Valent Pneumococcal Conjugate Vaccine in Children <5 years hospitalized for Meningitis in Lusaka, Zambia, 2010-2019

BACKGROUND

Despite the availability of vaccines, invasive bacterial diseases remain a public health concern and cause childhood morbidity and mortality. We investigated the characteristics of etiological agents causing bacterial meningitis in children <5 years in the years pre- (2010-2012) and post- (2014-2019) 10-valent pneumococcal conjugate vaccine (PCV10) introduction in Zambia.

METHODS

Streptococcus pneumoniae (Spn), Haemophilus influenzae (Hi), and Neisseria meningitidis (Nm) from cerebrospinal fluid (CSF) were identified by microbiological culture and/or real-time polymerase chain reaction.

RESULTS

During the surveillance period, a total of 3811 children were admitted with suspected meningitis, 16% (598 of 3811) of which were probable cases. Bacterial meningitis was confirmed in 37% (221 of 598) of the probable cases. Spn pneumoniae, Hi, and Nm accounted for 67% (148 of 221), 14% (31 of 221), and 19% (42 of 221) of confirmed cases, respectively. Thirty-six percent of pneumococcal meningitis was caused by 10-valent pneumococcal conjugate vaccine (PCV10) serotypes, 16% 13-valent pneumococcal conjugate vaccine and 39% by nonvaccine serotype (NVS). There was an association between the introduction of PCV10 vaccination and a decrease in both Spn meningitis and the proportion of PVC10 serotypes in the postvaccination period. Antimicrobial susceptibility of 47 Spn isolates revealed 34% (16 of 47) penicillin resistance. The 31 serotyped Hi accounted for 74% type b (Hib) and 10% type a (Hia). All 42 serogrouped Nm belonged to serogroup W.

CONCLUSIONS

There was a decline in pneumococcal meningitis and proportion of PCV10 serotypes in the postvaccination period. However, the serotype replacement with non-PCV10 serotypes and penicillin resistance warrant continued surveillance to inform policy.

Respiratory Viral and Bacterial Factors That Influence Early Childhood Asthma

Asthma is a chronic respiratory condition characterised by episodes of shortness of breath due to reduced airway flow. The disease is triggered by a hyperreactive immune response to innocuous allergens, leading to hyper inflammation, mucus production, changes in structural cells lining the airways, and airway hyperresponsiveness. Asthma, although present in adults, is considered as a childhood condition, with a total of about 6.2 million children aged 18 and below affected globally. There has been progress in understanding asthma heterogeneity in adults, which has led to better patient stratification and characterisation of multiple asthma endotypes with distinct, but overlapping inflammatory features. The asthma inflammatory profile in children is not well-defined and heterogeneity of the disease is less described. Although many factors such as genetics, food allergies, antibiotic usage, type of birth, and cigarette smoke exposure can influence asthma development particularly in children, respiratory infections are thought to be the major contributing factor in poor lung function and onset of the disease. In this review, we focus on viral and bacterial respiratory infections in the first 10 years of life that could influence development of asthma in children. We also review literature on inflammatory immune heterogeneity in asthmatic children and how this overlaps with early lung development, poor lung function and respiratory infections. Finally, we review animal studies that model early development of asthma and how these studies could inform future therapies and better understanding of this complex disease.

Twenty-Year Public Health Impact of 7- and 13-Valent Pneumococcal Conjugate Vaccines in US Children

Pneumococcal conjugate vaccines (PCVs) have been used in the United States since 2000. To assess the cumulative 20-year effect of PCVs on invasive pneumococcal disease (IPD) incidence among children <5 years of age, we analyzed Active Bacterial Core Surveillance data, conducted a literature review, and modeled expected and observed disease. We found that PCVs have averted >282,000 cases of IPD, including ≈16,000 meningitis, ≈172,000 bacteremia, and ≈55,000 bacteremic pneumonia cases. In addition, vaccination has prevented 97 million healthcare visits for otitis media, 438,914-706,345 hospitalizations for pneumonia, and 2,780 total deaths. IPD cases declined 91%, from 15,707 in 1997 to 1,382 in 2019. Average annual visits for otitis media declined 41%, from 78 visits/100 children before PCV introduction to 46 visits/100 children after PCV13 introduction. Annual pneumonia hospitalizations declined 66%-79%, from 110,000-175,000 in 1997 to 37,000 in 2019. These findings confirm the substantial benefits of PCVs for preventing IPD in children.

Serum antibody levels to pneumococcal polysaccharides 22F, 33F, 19A and 6A that correlate with protection from colonization and acute otitis media in children

BACKGROUND

Serotypes 22F and 33F have been added to a new pneumococcal-conjugate vaccine (PCV-15) because of their prevalence in causing invasive pneumococcal diseases (IPD).

METHOD

We measured anti-polysaccharide 22F, 33F, 19A and 6A antibodies in children before and after pneumococcal colonization and acute otitis media (AOM) episodes caused by these specific-serotypes. A two-step method for construction of correlate of protection (COP) models included using a generalized estimating equation for the relationship between antibody level, age and colonization history followed by logistic-regression modelling that included colonization or AOM episodes as independent variables, and age adjusted antibody level as the predictor.

RESULTS

A vaccine-induced serum antibody level of 0.45 μg/ml for 22F, 0.51 μg/ml for 6A and 4.1 μg/ml for 19A correlated with prevention of pneumococcal colonization by respective serotypes (insufficient number of cases for 33F to find COP against colonization). Antibody levels of 0.25 μg/ml for 22F, 33F and 6A and 2 μg/ml for 19A correlated with prevention of AOM by the respective serotypes.

CONCLUSIONS

A COP threshold of anti-22F, 33F, 19A and 6A serum antibodies for NP colonization and AOM in young children can be derived using GEE and logistic regression modelling.

A Systematic Review and Meta-Analysis of Serotype Distribution of Streptococcus Pneumoniae in Iran: Practical Evidence to Optimizing Local Vaccination Protocols

BACKGROUND

Little is known regarding the burden of predominant circulating serotypes of Streptococcus pneumoniae in Iran. Therefore, this study aimed to investigate the serotype distribution of pneumococcal diseases in Iran by using a comprehensive systematic review of available articles. ; Methods: A systematic literature search was carried out to identify papers published by Iranian authors in the Web of Science, PubMed, Scopus, Embase and Google Scholar electronic databases from January 2000 to December 2018. Then, eight publications that met our inclusion criteria were selected for data extraction and analysis by Comprehensive Meta-Analysis software. ; Results: In total, three studies reported the distribution of S. pneumoniae serotypes among patients, two studies among healthy individuals, and three studies among both groups. Of those studies, serotype 19A/F (17.9%; 95% CI: 13.6-23.0) was the most circulating serotype followed by 23A/F (12.3%; 95% CI: 7.7-19.2), 6A/B (11.0%; 95% CI: 8.0-14.9), and 14 (8.8%; 95% CI: 5.8-13.2). In contrast, the lowest circulating serotype was 60 (0.02%; 95% CI: 0.0-1.2), 29 (0.07%; 95% CI: 0.01-5.0), and 36 (0.09%; 95% CI: 0.04-2.1). Meta-regression results showed that prevalence of serotype 23A/F significantly increased each year about 0.2% (95% CI: 0.1-0.3, P <0.001, tau2 <0.001). ; Conclusion: In the present study, it was found that over the last decade, the most prevalent serotypes in Iran were 19, 23, 6, and 14, respectively. These findings provide practical evidence to select effective pneumococcal vaccine candidates for the prevention of invasive diseases in Iranian patients and also to compare our situation with others.

Vaccines against antimicrobial resistance: a promising escape route for multidrug resistance

Antibiotic resistance has become a global health problem requiring urgent intervention. The pace of development and frequency of transmission of antimicrobial resistance have tremendously surpassed the number of antibiotics developed in the past few decades. Emergence and transmission of multidrug-resistant genes, for example, mcr-1 and mcr-5.3, against the last resort of antibiotics has challenged the treatment options. Vaccination is a promising approach with no instance of antimicrobial resistance generation or transmission reported so far. The time required for developing a vaccine, extensive pre- and post-licensure studies and the financial constraints for the R&D has hampered vaccine development over the past few decades. Vaccine can prove to be an effective future strategy for combating antimicrobial resistance.

Non-linear relationships between children age and pneumococcal vaccine coverage: Important implications for vaccine prevention strategies

BACKGROUND

Streptococcus pneumoniae (S. pneumoniae) is an important pathogen causing both invasive and non-invasive infections in children, with significant morbidity and mortality worldwide. This study aimed to determine the potential relationships between age and vaccine coverage and between multiple phenotype-genotype characteristics of S. pneumoniae isolated from children.

METHODS

All S. pneumoniae isolates were tested for antimicrobial susceptibility, virulence genes, serotypes, and sequence types. The restricted cubic spline models were used to reveal potential relationships between children age and pneumococcal vaccine coverage.

RESULTS

For capsular-based vaccines, we observed a high coverage rate of 13-valent pneumococcal conjugate vaccine (PCV13, 85.8%) and a significantly non-linear relationship between children age and vaccine coverage (including PCV7, PCV10, and PCV13), with marked fluctuations in children aged < 2 years. For protein-based and pilus-based vaccine candidates, we demonstrated dynamic non-linear relationships between age and vaccine coverage, maintaining a stable and high coverage rate of ply and lytA for all age groups. Moreover, there were significantly high-dimensional corresponding relationships among multiple phenotype-genotype characteristics of S. pneumoniae isolates (such as ST271 associated with serotype 19F, PI-2, and extensively drug-resistance).

CONCLUSIONS

Our findings suggest that the age for high PCV coverage being children aged ≥ 2 years and also provide important evidence for supporting ply and lytA as priority candidate targets for the development of new-generation protein vaccines.

Emergence of Meningitis Caused by Nonvaccine Serotypes of Pneumococcus in Rural United States

Pneumococcal conjugate vaccines have decreased the rates of invasive pneumococcal disease (IPD) in children. Since vaccine introduction, however, rates of infection due to nonvaccine Streptococcus pneumoniae serotypes have increased. We now describe 3 meningitis cases due to the nonvaccine serotypes 35B and 11A from rural United States.

Autolysin (lytA) recombinant protein: a potential target for developing vaccines against pneumococcal infections

Purpose

N-acetylmuramoyl-l-alanine amidase known as lytA, is an immunogenic protein that plays an important role in the pathogenesis of Streptococcus pneumoniae. It is highly conserved among S. pneumoniae strains and is absent among other Streptococcus species. In the present study, the level of antibodies against the lytA recombinant protein was evaluated in healthy individuals' sera.

Materials and Methods

DNA was extracted from S. pneumoniae ATCC 49619 to amplify lytA gene by polymerase chain reaction assay. The lytA amplicon and pET28a vector were separately double digested using Nde-1 and Xho1 restriction enzymes and then ligated together with ligase enzyme. The recombinant plasmid was expressed in Escherichia coli BL21 strain and the lytA recombinant protein purified using nickel-nitrilotriacetic acid affinity chromatography. Western blot was carried to detect lytA recombinant protein. Sixty healthy individual's sera (at three age groups: group 1, <2; group 2, 2–40; and group 3, 60–90 years old) were collected and the titers of anti-lytA antibodies were determined.

Results

The lytA gene was highly expressed in E. coli BL21 host. The recombinant lytA protein was purified and confirmed by western blotting. Tukey test analysis showed that there were no significant differences among the age groups considering the anti-lytA titer of 10. However, at the anti-lytA titer of 60, significant differences were observed between group 1 vs. group 2 (p<0.001); group 1 vs. group 3 (p=0.003), and group 2 vs. group 3 (p=0.024).

Conclusion

The lytA protein seems to be a highly immunogenic antigen and a potential target for developing vaccines against pneumococcal infections.

Pneumococcal Vaccination for Children in Asian Countries: A Systematic Review of Economic Evaluation Studies

Background: Evidence on costs and health benefits of pneumococcal conjugate vaccine (PCV) for children in Asian countries is limited but growing. As a region with a considerably high burden of pneumococcal disease, it is prominent to have a comprehensive overview on the cost-effectiveness of implementing and adopting a PCV vaccination program. Methods: We conducted a systematic review from Pubmed and Embase to identify economic evaluation studies of PCV for children in Asian countries up to May 2020. Data extraction included specific characteristics of the study, input parameters, cost elements, cost-effectiveness results, and key drivers of uncertainty. The Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) statement was followed for this systematic review. The reporting quality of the included studies was evaluated using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) statement. Results: After the screening process on both the title and abstract and full text of 518 records, a total of 25 studies fulfilled the inclusion criteria, and were included in the review. The majority of included studies demonstrates that PCV for children is cost-effective in most of the Asian region, and even cost-saving in some countries. Most of the included studies implemented cost utility analysis (CUA) using either quality-adjusted life years (QALYs) or disability-adjusted life years (DALYs). Overall, the main drivers affecting the cost effectiveness were vaccine price, burden regarding pneumonia-related parameters, and the inclusion of herd effects. Conclusion: The children pneumococcal vaccination program appears to be a cost-effective intervention in Asia, and even cost-saving in certain conditions. Vaccine price, pneumonia-related disease burden, and the inclusion of the herd effect are observed as important key drivers in estimating cost-effectiveness in this region. Incorporating PCV in vaccination programs in this region was found to be highly favorable.