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•A correlate of protection for prevention of colonization in children for serotypes 15B and 15C.•Antibody levels correlated poorly with opsonophagocytic titers.•Low functional cross-reactivity between serotypes 15B and 15C in child sera was observed. 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. 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. 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. 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.

Background Acute pneumonia remains a leading cause of death among children below 5 years of age in the Democratic Republic of the Congo (DR Congo), despite introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) in 2013. Potential pathogens in the nasopharynx of hospitalised children with pneumonia have not been studied previously in DR Congo. Here we compare clinical characteristics, risk factors and nasopharyngeal occurrence of bacteria and viruses between children with severe and non-severe pneumonia. Methods Between June 2015 and June 2017, 116 children aged from 2 to 59 months hospitalised due to radiologically confirmed pneumonia at Panzi referral university hospital, Bukavu, Eastern DR Congo were included in the study and sampled from nasopharynx. A multiplex real-time PCR assay for detection of 15 different viruses and 5 bacterial species was performed and another multiplex PCR assay was used for pneumococcal serotype/serogroup determination. Results During the study period 85 (73%) of the children with radiologically confirmed pneumonia met the WHO classification criteria of severe pneumonia and 31 (27%) had non-severe pneumonia. The fatality rate was 9.5%. Almost all (87%) children were treated with antibiotics before they were hospitalised, in most cases with amoxicillin (58%) or trimethoprim-sulfamethoxazole (20%). The frequency of potential pathogens in the nasopharynx of the children was high, and any viral or bacterial nucleic acids present at high levels, irrespective of species or type, were significantly associated with severe pneumonia as compared with non-severe cases (52% versus 29%, p  = 0.032). White blood cell count > 20,000/μL and C-Reactive Protein > 75 mg/dL were associated with severe pneumonia at admission. Fatal outcome was in the multivariable analysis associated with having a congenital disease as an underlying condition. One or more pneumococcal serotypes/serogroups could be identified in 61 patients, and out of all identified serotypes 31/83 (37%) were non-PCV13 serotypes. Conclusions The occurrence of any bacteria or any viruses at high levels was associated with severe pneumonia at admission. Children with congenital disorders might need a higher attention when having symptoms of acute respiratory infection, as developed pneumonia could lead to fatal outcome.

•PCV10 reduced IPD caused by vaccine serotypes of Streptococcus pneumoniae.•PCV10 reduced IPD by vaccine serotypes in the non-targeted population.•IPD by serotypes 3, 6C, and 19A increased after the introduction of PCV10. In March 2010, the 10-valent pneumococcal conjugate vaccine (PCV10) was introduced into the routine immunization program in Brazil. We describe the pneumococcal serotypes that caused invasive pneumococcal diseases (IPD) before and after the introduction of PCV10 using data from a national laboratory-based surveillance system. We compared the prevalence of vaccine types (VT) and non-vaccine types (NVT) of Streptococcus pneumoniae in three periods, pre-PCV10 (January/2005-December/2009), early post-PCV10 (January/2010-December/2013), and late post-PCV10 (January/2014-December/2015), by episode in meningitis and non-meningitis cases and by age group. Changes in serotype prevalence in the early and late post-PCV10 periods were determined using pre-PCV10 period as a reference. A total of 8971 IPD isolates from patients aged 2 months to 99 years were analyzed. In the late post-PCV10 period, the VT-IPD reduction in the 2-month to 4-year age group was 83.4% for meningitis and 87.4% for non-meningitis cases; in the age groups 5–17 years, 18–64 years, and ≥65 years, VT declined by 56.1%, 54.1%, and 47.4%, respectively, in meningitis cases, and by 60.9%, 47.7%, and 53.4%, respectively, in non-meningitis cases. NVT-IPD increased throughout the study period, driven mainly by serotypes 3, 6C, and 19A, which remained the predominant types causing IPD in the late post-PCV10 period. We observed direct and indirect PCV10 protection against IPD caused by VT and a shift in the distribution of serotypes 5 years after the introduction of PCV10. Continued IPD surveillance is needed to evaluate the sustainability of the high prevalence of serotypes 3, 6C, and 19A, which were not included in PCV10.

The incidence of IPD in adults, while largely decreased from indirect effect of pediatric PCVs, remains high. To describe differences in the expected serotype coverage and incidence of IPD by V116, a novel adult-specific PCV, and other licensed PCVs used in adults. We used national IPD surveillance serotype distribution data from 7 countries (US, Canada, UK, Germany, France, Spain, and Australia). We calculated serotype coverage offered by V116 and PCV20 in adults 65+ (or 60+) years old in 2022 (2019 for UK, France). For all countries except Germany, we reported incidence/notification rates of IPD due to serotypes in V116 versus other PCVs in 2019. As an example, we estimated annual numbers of US cases potentially prevented, assuming 100 % vaccine efficacy and uptake for both vaccines. From 7 countries, coverage conferred by V116 in adults 65+ in 2019–2022 ranged from 66 %–88 % of IPD cases while PCV20 coverage ranged from 50 %–66 %. The incidence of IPD among adults 65+ caused by serotypes included in V116 is higher in all six countries compared to other PCVs in 2019. In US, the annual incidence of IPD (per 100,000) among 65+ was 24; the incidence caused by serotypes in V116 was 20 cases compared to 12 from PCV20 serotypes. Of the estimated total 12,800 annual IPD cases in 2019 in the US, V116 could potentially prevent ∼8200 cases compared to ∼5000 by PCV20. Based on IPD surveillance data from key countries, serotype coverage by V116 was ∼16–33 % higher than that by PCV20 among adults 65+ years in 2022 (data for UK, France from 2019). V116 includes serotypes responsible for the majority of IPD and is expected to prevent more IPD cases than PCV20 among 65+.

The introduction of pneumococcal conjugate vaccines (PCVs) since 2000 has altered the epidemiology of invasive (IPD) and non-invasive pneumococcal diseases (NIPD). This study aims to analyze trends in pneumococcal serotype distribution among children in Mexico, focusing on the period following the introduction of PCV13, and assess the potential impact of future vaccines. Pneumococcal isolates were collected from hospitalized children in participating hospitals from January 2012 to December 2023. Serotype distribution was analyzed in children under <5 years and those aged ≥5 to 17.9 years. The average annual change (AAC) in serotype proportions was calculated, and trends were analyzed using the Cochran-Armitage test. Serotype 19A was the most frequent PCV13 serotype, followed by serotypes 3 and 19F, in both age groups. Serotype 33F, included in PCV15 and PCV20, was absent in children aged ≥5‐17.9 years. Among PCV20 serotypes, serotype 15B was the most common, and serotype 17F, covered by PCV24, showed a significant increase in the older age group (p = 0.037). No significant trends in the increase or decrease of individual serotypes were found, except for serotypes 17F and serotype 34, which increased in both age groups. A decrease in serotypes covered by PCV13 (excluding serotypes 3, 19A, and 19F) was observed in both age groups (p = 0.04, 0.002). A significant increase in non-PCV13 serotypes occurred in children aged ≥5‐17.9 years (p = 0.023). After a decade of the introduction of PCV13 in Mexico, 10 of the 13 vaccine serotypes have not been detected in the past six years. However, serotypes 3, 19A, and 19F persist at high frequencies as causes of IPD and NIPD in children. Ongoing robust surveillance is critical for identifying emerging pneumococcal serotypes, selecting appropriate vaccines for each country, and developing next-generation vaccine formulations.

•Vaccine-type pneumococcal carriage declined by >90% after PCV10 introduction.•Effectiveness of 4 PCV10 doses against carriage of vaccine serotypes was 97.3%.•No protection against carriage of vaccine-related serotypes (including 6A and 19A) was observed.•Colonization by non-typeable H. influenzae increased from 26.0% at baseline to 43.6% post-PCV10. In March 2010, Brazil introduced the 10-valent pneumococcal conjugate vaccine (PCV10) in the routine infant immunization program using a 4-dose schedule and catch-up for children <23months. We investigated PCV10 effect on nasopharyngeal carriage with vaccine-type Streptococcus pneumoniae (Spn) and non-typeable Haemophilus influenzae (NTHi) among children in São Paulo city. Cross-sectional surveys were conducted in 2010 (baseline) and 2013 (post-PCV10). Healthy PCV-naïve children aged 12–23months were recruited from primary health centers during immunization campaigns. Nasopharyngeal swabs were collected and tested for Hi; for Spn, all baseline and a stratified random sample of 400 post-PCV10 swabs were tested. We compared vaccine-type Spn and NTHi carriage prevalence pre-/post-PCV10, and used logistic regression to estimate PCV10 effectiveness (1-adjusted odds ratio×100%). Overall 501 children were included in the baseline and 1167 in the post-PCV10 survey (including 400 tested for Spn). Spn was detected in 40.3% of children at baseline and 48.8% post-PCV10; PCV10 serotypes were found in 19.8% and 1.8% respectively, representing a decline of 90.9% (p<0.0001). Carriage of vaccine-related serotypes increased (10.8–21.0%, p<0.0001), driven primarily by a rise in serotype 6C (1.8–11.2%, p<0.0001); carriage of serotypes 6A and 19A did not significantly change. PCV10 effectiveness (4 doses) against vaccine-type carriage was 97.3% (95% confidence interval 88.7–99.3). NTHi prevalence increased from 26.0% (130/501) to 43.6% (509/1167, p<0.0001); PCV10 vaccination seemed significantly associated with NTHi carriage, even after adjusting for other known risk factors. Carriage with PCV10 serotypes among toddlers declined dramatically following PCV10 introduction in São Paulo, Brazil. No protection of PCV10 against NTHi was observed. Our findings contribute to a growing body of evidence of PCV10 impact on vaccine-type carriage and highlight the importance of PCV10 as a tool to reduce the burden of pneumococcal disease in Brazil and globally.

We report 2 adult cases of invasive disease in Japan caused by Streptococcus oralis that expressed the serotype 3 pneumococcal capsule and formed mucoid colonies. Whole-genome sequencing revealed that the identical serotype 3 pneumococcal capsule locus and hyl fragment were recombined into the genomes of 2 distinct S. oralis strains.

Streptococcus pneumoniae is a major cause of severe invasive disease associated with high mortality and morbidity worldwide. A total of 2908 pneumococcal isolates were analyzed between 2006 and 2019. Gold standard pneumococcal serotyping (the Neufeld-Quellung reaction) was performed to identify the serotypes associated with infection in children < 5 years in Argentina and agar dilution method was carried out to determine their profiles to 14 antimicrobial agents. In 2012, the 13-valent pneumococcal conjugate vaccine (PCV13) was included in the National Immunization Program. In this work we have analyzed the local epidemiology of invasive pneumococcal diseases before and after the introduction of this vaccine in order to understand the epidemiological relevance and impact of PCV13. During the periods compared in the present study there was a significant increase in the proportion of non-PCV13 serotypes, serogroup 24 (246.7%) and 12F (85.7%), and a significant decrease in PCV13 serotypes, including serotypes 14 (91.2%), 5 (95.6%) and 1 (84.6%) among others. Another observation was that serotypes 3 (7.4%) and 19A (4.9%) still remain among the most frequent serotypes despite being part of the PCV13 formulation. Regarding antimicrobial resistance, in the present study we observed an increase in erythromycin resistance during the period of study mainly associated to serotype 14 in the pre-PCV13 period and to serogroup 24 in the post-PCV13 period, which also was the major NVT serotype associated with antimicrobial resistance and MDR. Serotypes 14, 24A/B/F and 19A were in the first three places among isolates resistant to all the antibiotics tested. Our data highlight the importance of continuous surveillance to assess the impact of pneumococcal vaccines and the use of antibiotics in the dynamic of pneumococcal serotypes.

A novel 13-valent pneumococcal conjugate vaccine (PCV13-TT) has been widely used in China since its licensure in 2019. The prelicensure pivotal clinical study (PCV13–002) showed strong immune responses against 13 serotypes with PCV13-TT using two different 3P + 1 schedules starting at either 2 (PCV13-2M) or 3 months (PCV13-3M) of age. To assess antibody persistence, healthy Chinese toddlers from PCV13–002 were recalled for blood collection at 1 and 2 years post booster dose. Antibody persistence was evaluated using ELISA and OPA assay methods to measure serotype-specific antibodies. Similar immune responses were noted for both PCV13-3M and PCV13-2M groups. IgG GMCs remained high (ranging from 0.39 to 4.68 μg/mL) through 2 years post 4 doses of PCV13-TT, with IgG positive rates against most serotypes maintained at ≥90%. Both OPA GMTs and OPA positive rates remained high compared to levels observed at 1 month post booster. After complete dosing schedule of PCV13-TT starting from either 2 months or 3 months, the antibody level declined through 1 year and 2 years post booster dose, while still remained at relatively high levels at the two timepoints as compared to those observed at 1 month post booster dose for the majority of serotypes. Clinical Trial Registration: CTR20182353. •The first study evaluating the antibody persistence of a novel tetanus toxoid-based PCV13.•Comparable antibody persistence between two dosing schedules through 2 years.•IgG GMCs against all 13 serotypes sustained higher than the WHO recognized cut-off 0.35 μg/mL.•IgG positive rates against most serotypes sustained at high levels (≥90 %).

Streptococcus pneumoniae remains a leading global cause of pediatric morbidity and mortality, with evolving serotype distributions following vaccine introductions. This national surveillance study characterizes the contemporary epidemiology of invasive pneumococcal pneumonia (IPP) among Argentine children under 11 years (2022–2024). We analyzed 316 invasive pneumonia isolates from 78 pediatric hospitals across 24 jurisdictions, obtained through Argentina's National IPD Surveillance System. Serotyping (Quellung reaction) and antimicrobial susceptibility testing (CLSI agar dilution) were performed. Isolates were stratified by age (<2, 2–5, 6–10 years) and clinical presentation. The surveillance showed persistent dominance of vaccine-type serotypes 3 (22.1 %), 19A (12.0 %), and 14 (6.3 %), alongside emerging non-vaccine type 12F (6.7 %). Distinct age-specific patterns emerged, with serotypes 7F and 1 predominating in 6-10 years and 24A exclusively detected in infants. Serotypes 3 and 19A demonstrated a significant association with pleural effusion, while serotype 24B was the dominant variant in non-effusion invasive pneumonia cases. Antimicrobial susceptibility testing revealed high susceptibility to β-lactams, with 94 % of isolates susceptible to penicillin and amoxicillin. However, a concerning 24.3 % rate of multidrug resistance was observed, primarily concentrated in serotypes 19A and 24F/A/B. Our analysis breaks significant shifts in pneumococcal serotype epidemiology following PCV13 implementation, with three key patterns emerging: (1) persistent circulation of vaccine-type serotypes 3 and 19A, (2) emergence of non-vaccine type particularly 12F and 24B, and (3) dynamic fluctuations in serotype distribution suggesting ongoing selective pressure. These evolving epidemiological patterns, coupled with concerning multidrug resistance in key serotypes 19A and 24F/A/B, underscore two critical needs: enhanced national surveillance systems to monitor serotype replacement, and the evaluation of next-generation vaccines that provide broader coverage against both persistent vaccine-types and emerging non-vaccine types.