Unswitched memory B cell deficiency in children with sickle cell disease and response to pneumococcal polysaccharide vaccine.

Early mortality in sickle cell disease (SCD) is attributed to increased infections due to loss of splenic function. Marginal zone B cells are important for initial opsonization of pathogens and can be absent in spleen histopathology in SCD. The frequency of unswitched memory B cells (UMBC), the circulating correlate of marginal zone B cells, reflects the immunologic function of the spleen. We hypothesized that asplenia in SCD is associated with alterations in the peripheral blood lymphocyte population and explored whether UMBC deficiency was associated with a clinical phenotype. We analyzed B cell subsets and clinical history for 238 children with SCD and 63 controls. The median proportion of UMBCs was lower in children with SCD compared with controls (4.7% vs. 6.6%, p < .001). Naïve B cells were higher in SCD compared with controls (80.6 vs. 76.3%, respectively, p = .02). UMBC frequency declined by 3.4% per year increase in age in SCD (95% CI: 2%, 4.7%, p < .001), but not in controls. A majority of children in all cohorts had an IgM concentration in the normal range for age and there were no differences between groups (p = .13). Subjects developed titers adequate for long-term protection to fewer serotypes in the polysaccharide vaccine than controls (14.7 vs. 19.4, p < .001). In this cohort, bacteremia was rare and specific clinical complications were not associated with UMBC proportion. In summary, UMBC deficiency occurs in SCD and is associated with age. Future studies should investigate B cell subsets prospectively and identify the mechanism of B cell loss in the spleen.

Clinical and economic burden of acute otitis media caused by Streptococcus pneumoniae in European children, after widespread use of PCVs-A systematic literature review of published evidence.

BACKGROUND: Acute otitis media (AOM) is a common childhood disease frequently caused by Streptococcus pneumoniae. Pneumococcal conjugate vaccines (PCV7, PCV10, PCV13) can reduce the risk of AOM but may also shift AOM etiology and serotype distribution. The aim of this study was to review estimates from published literature of the burden of AOM in Europe after widespread use of PCVs over the past 10 years, focusing on incidence, etiology, serotype distribution and antibiotic resistance of Streptococcus pneumoniae, and economic burden. METHODS: This systematic review included published literature from 31 European countries, for children aged ≤5 years, published after 2011. Searches were conducted using PubMed, Embase, Google, and three disease conference websites. Risk of bias was assessed with ISPOR-AMCP-NPC, ECOBIAS or ROBIS, depending on the type of study. RESULTS: In total, 107 relevant records were identified, which revealed wide variation in study methodology and reporting, thus limiting comparisons across outcomes. No homogenous trends were identified in incidence rates across countries, or in detection of S. pneumoniae as a cause of AOM over time. There were indications of a reduction in hospitalization rates (decreases between 24.5-38.8% points, depending on country, PCV type and time since PCV introduction) and antibiotic resistance (decreases between 14-24%, depending on country), following the widespread use of PCVs over time. The last two trends imply a potential decrease in economic burden, though this was not possible to confirm with the identified cost data. There was also evidence of an increase in serotype distributions towards non-vaccine serotypes in all of the countries where non-PCV serotype data were available, as well as limited data of increased antibiotic resistance within non-vaccine serotypes. CONCLUSIONS: Though some factors point to a reduction in AOM burden in Europe, the burden still remains high, residual burden from uncovered serotypes is present and it is difficult to provide comprehensive, accurate and up-to-date estimates of said burden from the published literature. This could be improved by standardised methodology, reporting and wider use of surveillance systems.

Pneumococcal vaccination and primary care presentations for acute respiratory tract infection and antibiotic prescribing in older adults.

BACKGROUND: While the 23-valent pneumococcal polysaccharide vaccine (PPV23) has demonstrated its role in preventing severe pneumococcal disease, its impact on more non-specific conditions like acute respiratory tract infection (ARI) and lower respiratory tract infections (LRTI) remains unclear. We aimed to investigate the role of PPV23 in prevention of presentations for ARI and LRTI and related antibiotic prescriptions among older adults in primary care. METHODS: Using a nationwide general practice dataset, we followed a cohort of regularly attending patients aged ≥65 years from 1 January 2014 until 31 December 2018 for presentations for ARI, LRTI, and related antibiotic prescriptions. Associations between PPV23 receipt and each outcome were assessed using a multiple failures survival model to estimate hazard ratios (HR) adjusted for age, sex, socioeconomic status, and various health measures. RESULTS: A cohort of 75,264 patients aged ≥65 years (mean 75.4, 56% female) in 2014 was followed. The incidence of presentations for ARI, ARI-related antibiotic prescription, LRTI, and LRTI-related antibiotic prescription was 157.6, 76.0, 49.6, and 24.3 per 1000 person-years, respectively. Recent PPV23 vaccine receipt was associated with a small reduction in ARI presentations (adjusted HR vaccinated vs. unvaccinated 0.96; 95%CI 0.94-0.98; p = 0.002); however, there was no reduction in ARI-related antibiotic prescription, LRTI presentation, nor LRTI-related antibiotic prescription (adjusted HR were 0.99[95%CI 0.96-1.03], 1.04[95%CI 0.99-1.09], 1.07[95%CI 1.00-1.14]). CONCLUSION: PPV23 vaccination in older adults may result in a small reduction in the incidence of total ARI presentations in primary care. However, the effect is small and residual confounding cannot be excluded.

Retrospective study on the health and economic burden of hospitalized patients due to pneumonia and invasive pneumococcal infections in Belgium settings.

INTRODUCTION: pneumococcal infections are associated with high morbidity, hospitalisation and mortality. The objective of this study was to investigate the health and economic burden of all-cause pneumonia and invasive pneumococcal disease in Belgian hospital settings, by patient's age and risk profile. METHODS: This descriptive retrospective study was conducted in 17 Belgian hospitals. Univariate and multivariate logistic linear regression models were performed. The Health Insurance and patient's cost perspectives were considered because a few studies report these costs. RESULTS: The analysis has included 4,712 hospital admissions over the year 2018. Median hospitalization costs were higher for invasive pneumococcal infection diagnosis than for all-cause pneumonia (p < 0,001), respectively 4,051€ and 3,362€. Other factors associated with higher hospitalization cost were patient's high-risk profile, admission to emergency unit, transfer from nursing home, admission to intensive care unit and length of stay. CONCLUSION: Streptococcus pneumoniae infections remain a public health problem with significant cost for the Health Insurance and poor prognosis. Invasive pneumococcal infections are associated with longer hospital stays and required more intensive care than all other causes of pneumonia, in addition to be more costly, which justifies more attention for vaccination. This study also suggests an increase of economic and health burden with age and presence of underlying conditions.

[Vaccination status and factors associated with pneumococcal vaccination in geriatric short-stay care]. / Statut vaccinal et facteurs associés à la vaccination antipneumococcique en court séjour gériatrique.

Nearly two-thirds of geriatric short-stay patients were eligible for pneumococcal vaccination. Among patients eligible for vaccination, less than 5 % had received at least one injection of pneumococcal vaccine on admission. We found no modifiable factors associated with vaccination status, but several avenues for improving vaccination coverage.

Pneumococcal Perplexity: Improving Awareness of Updated Pneumococcal Vaccination Recommendations in Two Large Military Treatment Facilities.

INTRODUCTION: Vaccinations are an essential aspect of preventive medicine. In October 2021, the pneumococcal conjugate vaccine-20 (PCV-20) and PCV-15 were authorized for use in adults by the U.S. FDA. In 2022, the Advisory Committee on Immunization Practices (ACIP) subsequently published updated pneumococcal vaccination recommendations that incorporate both PCV-20 and PCV-15. Pneumococcal vaccination is effective in reducing pneumococcal disease, particularly in high-risk patient groups such as those with chronic lung disease; however, the updated dosing schedule for pneumococcal vaccinations can be quite confusing, especially if patients have previously received "older" vaccinations, such as pneumococcal polysaccharide vaccine-23 or PCV-13. The purpose of this quality improvement project was to increase providers' knowledge of current ACIP pneumococcal vaccination recommendations, including indications and dosing schedule, and to improve pneumococcal vaccination rates among eligible adults and children. MATERIALS AND METHODS: Focused education sessions were presented to primary care and subspecialty residents, fellows, and staff at Brooke Army Medical Center and Wilford Hall Ambulatory Surgical Center regarding current ACIP pneumococcal vaccination recommendations. Sessions included information about PCV-15 and PCV-20 vaccines, indications for vaccination, and dosing schedules. Subjective knowledge of updated ACIP pneumococcal vaccination recommendations was assessed among primary care and subspecialty residents, fellows, and staff via an anonymous survey both pre- and post-intervention. Number of PCV-20 vaccinations given and estimated vaccination rates of patients aged 19 to 64 years with asthma were assessed pre- and post-intervention over a 6 month time span. RESULTS: Of surveyed providers, only 9% discussed vaccinations at every visit and 11% did not discuss vaccinations at all. There was a statistically significant increase in providers' knowledge of pneumococcal vaccination guidelines for children post-intervention (P = .01) but no statistically significant increase in knowledge for guidelines for adults, for patients that have received prior pneumococcal vaccines, or in overall confidence in recommending pneumococcal vaccines. There was a 17% increase in the number of PCV-20 vaccinations given post-intervention (198 pre-intervention, 232 post-intervention). The estimated PCV-20 vaccination rate for adults aged 19 to 64 years with asthma increased from 14.9% pre-intervention to 19.5% post-intervention (P = .33). CONCLUSIONS: There is a significant knowledge gap regarding ACIP pneumococcal vaccination recommendations among military providers and a low pneumococcal vaccination rate for adults aged 19 to 64 years with asthma at Joint Base-San Antonio MTFs. Focused education sessions were effective in increasing providers' knowledge of updated pneumococcal vaccination recommendations, confidence in recommending vaccines, total number of pneumococcal vaccinations given, and estimated pneumococcal vaccination rate for adults with asthma. The validity of conclusions drawn from our data were limited because of discordant numbers of survey respondents as well as potentially inaccurate estimates of pneumococcal vaccination rates pre- and post-intervention. Despite this, the results warrant continued education of pneumococcal vaccines, indications, and dosing schedules.

Real-World Coverage With Influenza, Pneumococcal, and Herpes Zoster Vaccines Among Patients With Rheumatic Diseases in a Nationwide Healthcare Plan.

OBJECTIVE: Vaccination against preventable infections is important for the management of rheumatic diseases (RDs). This study assessed the vaccination coverage and predictors among patients with RDs using real-world data from Israel. METHODS: This retrospective cross-sectional study, based on a Maccabi Healthcare Services database, included adult patients diagnosed with rheumatoid arthritis (RA), psoriatic arthritis (PsA), and systemic lupus erythematosus (SLE), as of April 30, 2019. Age-specific vaccination coverage for influenza (past year), pneumococcal (23-valent pneumococcal polysaccharide vaccine [PPSV23] and/or 13-valent pneumococcal conjugate vaccine [PCV13]), and live-attenuated herpes zoster (HZ) vaccines (past 5 years) was reported. Logistic regression was used to investigate predictors of vaccination. RESULTS: The study included 14,528 patients (RA: n = 6932; PsA: n = 4395; SLE: n = 1951; > 1 condition: n = 1250). Influenza vaccine coverage among patients with RA, PsA, and SLE was 45.1%, 36.2%, and 33.7%, respectively. For PPSV23, corresponding rates were 19.6%, 16.2%, and 12.6%, respectively. In the elderly population (≥ 65 years), 63.2% had influenza vaccine in the past year and 83.4% had a PPSV23 vaccine in the past 5 years or at age ≥ 65. For PCV13 and HZ, coverage in the overall study population was low at 4.8% and 3.6%, respectively. Central residence and treatment with corticosteroids and biologic or targeted synthetic disease-modifying antirheumatic drugs within the past 5 years were significant predictors of vaccination coverage across all vaccines (P < 0.05). Other predictors varied by vaccine, including female sex (influenza, PPSV23, PCV13), age (influenza, PPSV23), chronic comorbidities (influenza, PPSV23, PCV13), shorter disease duration (PCV13), and high socioeconomic status (PCV13, HZ). CONCLUSION: This study demonstrated suboptimal coverage of influenza, pneumococcal, and HZ vaccination in patients with RA, PsA, and SLE, in particular among younger adults in Israel.

Quality Improvement Interventions to Enhance Vaccine Uptake in Cancer Patients: A Systematic Review.

INTRODUCTION: Cancer patients, because of their compromised immune responses, face a higher risk of preventable infections, leading to increased morbidity and mortality. Despite this, vaccination rates among these patients are suboptimal, and research on effective interventions to improve vaccination rates is limited. METHODS: We conducted a comprehensive search in PubMed and Cochrane Library for studies investigating quality improvement (QI) interventions targeting vaccine uptake in cancer patients. Two authors independently screened, extracted data, and analyzed studies, resolving any discrepancies through consensus. RESULTS: Thirteen studies met the inclusion criteria, published between 2014 and 2022. Seven studies focused on the influenza vaccine, five on the pneumococcal vaccine, and one on both. Twelve studies used multiple interventions, whereas one used a single intervention. Most interventions aimed to enhance patient and family knowledge and identify eligible patients before their appointments. All studies demonstrated improved vaccine uptake after implementing the interventions. CONCLUSIONS: A variety of QI interventions have effectively increased pneumococcal and influenza vaccine uptake among cancer patients. Future research should address roadblocks to implementation and explore the effect of these interventions on other vaccines.

Surveillance of pneumococcal serotypes in adults hospitalised with acute lower respiratory tract infection in Bristol, UK.

INTRODUCTION: Pneumococcus remains a major cause of adult lower respiratory tract infections (LRTI). Few data exist on the relative contribution of serotypes included in pneumococcal vaccines to community-acquired pneumonia (CAP) and non-pneumonic (NP) LRTI. We measured the burden of all and vaccine-serotype pneumococcal respiratory infection following SARS-CoV-2 emergence to inform evidence-based vaccination policy. METHODS: A prospective cohort study at two Bristol hospitals (UK) including all adults age ≥ 18-years hospitalised with acute lower respiratory tract disease (aLRTD) from Nov2021-Nov2022. LRTI patients were classified as: a) radiographically-confirmed CAP (CAP+/RAD+), b) clinically-diagnosed CAP without radiological confirmation (CAP+/RAD-), or c) NP-LRTI. Pneumococcus was identified by blood culture, BinaxNOW™and serotype-specific urine antigen detection assays (UAD). RESULTS: Of 12,083 aLRTD admissions, 10,026 had LRTI and 2,445 provided urine: 1,097 CAP + RAD+; 207 CAP + RAD-; and 1,141 NP-LRTI. Median age was 71.1y (IQR57.9-80.2) and Charlson comorbidity index = 4 (IQR2-5); 2.7 % of patients required intensive care, and 4.4 % died within 30-days of hospitalisation. Pneumococcus was detected in 280/2445 (11.5 %) participants. Among adults aged ≥ 65y and 18-64y, 12.9 % (198/1534) and 9.0 % (82/911), respectively, tested pneumococcus positive. We identified pneumococcus in 165/1097 (15.0 %) CAP + RAD+, 23/207 (11.1 %) CAP + RAD-, and 92/1141 (8.1 %) NP-LRTI cases. Of the 280 pneumococcal cases, 102 (36.4 %) were due to serotypes included in PCV13 + 6C, 115 (41.7 %) in PCV15 + 6C, 210 (75.0 %) in PCV20 + 6C/15C and 228 (81.4 %) in PPV23 + 15C. The most frequently identified serotypes were 8 (n = 78; 27.9 % of all pneumococcus), 7F (n = 25; 8.9 %), and 3 (n = 24; 8.6 %). DISCUSSION: Among adults hospitalised with respiratory infection, pneumococcus is an important pathogen across all subgroups, including CAP+/RAD- and NP-LRTI. Despite 20-years of PPV23 use in adults ≥ 65-years and herd protection due to 17-years of PCV use in infants, vaccine-serotype pneumococcal disease still causes a significant proportion of LRTI adult hospitalizations. Direct adult vaccination with high-valency PCVs may reduce pneumococcal disease burden.

The potential impact of PCV-13, PCV-15 and PCV-20 vaccines in Colombia.

PURPOSE: To provide information about which pneumococcal vaccine could have greater coverage in Colombia. METHODS: This is a retrospective analysis of patients diagnosed with invasive pneumococcal disease (IPD) between 2015 and 2019 in Bogotá, Colombia. We compared the theoretical serotype coverage of the available anti-pneumococcal vaccines (i.e., PCV-10, PCV-10 SII, PCV-13, PCV-15, PCV-20, PCV-21, PCV24, PPSV-23) and the non-vaccine-covered serotypes stratified by age. RESULTS: 690 IPD cases were included. In children ≤5 y/o, of the approved vaccines PCV-20 showed the most theoretical protection (71.3 % [149/209]), while in adults aged 18-64 y/o was PCV-20 (61.8 % [164/265]), and in those ≥65 y/o was PPSV-23 (58.1 % [100/172]) followed by PCV-20 (55.2 % [95/172]). The non-covered serotypes represented one-third of the cohort (33.9 % [234/690]), being 6C (20.5 % [48/234]), 15A (12.8 % [30/234]), and 23A (11.5 % [27/234]) the most prevalent. CONCLUSION: Introducing PCV-20 for children and PCV-20 along with a PPSV-23 booster in adults may reduce IPD frequency in all ages in Colombia. The inclusion of non-covered serotypes is required for future vaccines.

[Which vaccines for COPD patients?] / Quels vaccins pour les patients atteints de BPCO ?

WHICH VACCINES FOR COPD PATIENTS? Patients with chronic obstructive pulmonary disease (COPD) are at high risk of bacterial or viral respiratory infections, which can worsen their symptoms and trigger respiratory exacerbations. Vaccines are recommended in accordance with the vaccine recommendation calendar. Seasonal influenza vaccination is recommended every year. Pneumococcal vaccination is renewed every 5 years, according to a schedule adapted to previous vaccination status. The SARS-Cov2 vaccine is administered according to current recommendations that evolves with the virus circulation. Certain populations are also vaccinated against pertussis and shingles.

QUELS VACCINS POUR LES PATIENTS ATTEINTS DE BPCO ? Les patients atteints de bronchopneumopathie chronique obstructive (BPCO) sont à haut risque d'infections respiratoires bactériennes ou virales, sources de majoration des symptômes et d'exacerbations respiratoires. La vaccination par le vaccin antigrippal saisonnier leur est recommandée tous les ans. La vaccination antipneumococcique est renouvelée tous les cinq ans selon un schéma adapté au statut vaccinal antérieur. Le vaccin anti-SARS-CoV-2 est quant à lui administré selon des recommandations évolutives en fonction du développement de la circulation du virus. Enfin, certains patients bénéficient des vaccins contre la coqueluche et le zona.

Association between regular physical activity and pneumonia-related hospitalization according to pneumococcal vaccination status: The VENUS study.

BACKGROUND: Little is known about the impact of physical activity (PA) and PPSV23 vaccination on pneumonia-related hospitalizations. This study examined the association between regular PA and pneumonia-related hospitalization according to PPSV23 vaccination status in older adults. METHODS: This retrospective cohort study was conducted using health checkup data, medical care claims data, and vaccination records from two Japanese municipalities. Residents aged ≥65 years who had undergone a health checkup between April 2016 and March 2021 were categorized into a PPSV23 vaccinated or unvaccinated cohort. Each cohort was further divided into a PA group and no PA group. The hazard ratio (HR) of PA for pneumonia-related hospitalization was calculated for each cohort while adjusting for sex, age, comorbidities, and metabolic syndrome. RESULTS: The vaccinated cohort comprised 16,295 participants (no PA: 5,139, PA: 11,156), and the unvaccinated cohort comprised 7,998 participants (no PA: 2,671, PA: 5,327). In the vaccinated cohort, the PA group had a significantly lower hazard for pneumonia-related hospitalization than the no PA group (adjusted HR: 0.58, P = 0.004). However, PA was not associated with pneumonia-related hospitalization in the unvaccinated cohort (adjusted HR: 0.70, P = 0.270). CONCLUSIONS: PA can reduce the risk of pneumonia-related hospitalization in vaccinated persons. Interventions that increase both vaccination rates and PA habits may help to reduce these hospitalizations in older adults.

Pneumococcal Vaccination Lowers the Risk of Alzheimer's Disease: A Study Utilizing Data from the IBM® MarketScan® Database.

Previous studies demonstrated an association between influenza vaccination and the likelihood of developing Alzheimer's disease. This study was aimed at assessing whether pneumococcal vaccinations are associated with a lower risk of Alzheimer's disease based on analysis of data from the IBM® MarketScan® Database. Vaccinated and unvaccinated matched cohorts were generated using propensity-score matching with the greedy nearest-neighbor matching algorithm. The conditional logistic regression method was used to estimate the relationship between pneumococcal vaccination and the onset of Alzheimer's disease. There were 142,874 subjects who received the pneumococcal vaccine and 14,392 subjects who did not. The conditional logistic regression indicated that the people who received the pneumococcal vaccine had a significantly lower risk of developing Alzheimer's disease as compared to the people who did not receive any pneumococcal vaccine (OR=0.37; 95%CI: 0.33-0.42; P-value < .0001). Our findings demonstrated that the pneumococcal vaccine was associated with a 63% reduction in the risk of Alzheimer's disease among US adults aged 65 and older.

Cost-effectiveness of 20-valent pneumococcal conjugate vaccine in US infants.

BACKGROUND: As of June 2023, two pneumococcal conjugate vaccines, 20- (PCV20) and 15- (PCV15) valent formulations, are recommended for US infants under a 3 + 1 schedule. This study evaluated the health and economic impact of vaccinating US infants with a new expanded valency PCV20 formulation. METHODS: A population-based, multi cohort, decision-analytic Markov model was developed to estimate the public health impact and cost-effectiveness of PCV20 from both societal and healthcare system perspectives over 10 years. Epidemiological data were based on published studies and unpublished Active Bacterial Core Surveillance System (ABCs) data. Vaccine effectiveness was based on PCV13 effectiveness and PCV7 efficacy studies. Indirect impact was based on observational studies. Costs and disutilities were based on published data. PCV20 was compared to both PCV13 and PCV15 in separate scenarios. RESULTS: Replacing PCV13 with PCV20 in infants has the potential to avert over 55,000 invasive pneumococcal disease (IPD) cases, 2.5 million pneumonia cases, 5.4 million otitis media (OM) cases, and 19,000 deaths across all ages over a 10-year time horizon, corresponding to net gains of 515,000 life years and 271,000 QALYs. Acquisition costs of PCV20 were offset by monetary savings from averted cases resulting in net savings of $20.6 billion. The same trend was observed when comparing PCV20 versus PCV15, with a net gain of 146,000 QALYs and $9.9 billion in net savings. A large proportion of the avoided costs and cases were attributable to indirect effects in unvaccinated adults and elderly. From a health-care perspective, PCV20 was also the dominant strategy compared to both PCV13 and PCV15. CONCLUSIONS: Infant vaccination with PCV20 is estimated to further reduce pneumococcal disease and associated healthcare system and societal costs compared to both PCV13 and PCV15.

Cost-effectiveness of the 20-valent pneumococcal conjugate vaccine versus the 23-valent pneumococcal polysaccharide vaccine for older adults in South Korea.

BACKGROUND: Despite the demonstrated immunogenicity and safety of the 20-valent pneumococcal conjugate vaccine (PCV20) in older adults, the cost-effectiveness of the PCV20 was not examined compared to the 23-valent pneumococcal polysaccharide vaccine (PPSV23) in South Korea. Therefore, this study aimed to evaluate the cost-effectiveness of PCV20 compared with PPSV23 in adults aged 65 years and older in South Korea. METHODS: We constructed a Markov model that included susceptible states, invasive pneumococcal disease (IPD), non-bacteremic pneumonia (NBP), and death. The population was categorized by disease risk status (low risk, moderate risk, and high risk) and age group (65-74/75-84/85-99 years) at model entry. The annual incidence and mortality of IPD and NBP associated with PCV20 and PPSV23 were estimated based on serotype coverage, vaccine coverage, and vaccine effectiveness. The disease costs and utilities were obtained from previous studies. The incremental cost-effectiveness ratio (ICER) was used to evaluate cost-effectiveness within the threshold of 16,824 USD per quality-adjusted life-year (QALY). RESULTS: Among the total population (n = 8,843,072), PCV20 prevented 1941 and 50,575 cases of IPDs and NBPs, respectively, and 898 and 8593 deaths due to IPDs and NBPs compared to PPSV23. The total medical cost per person was 12.11 USD higher in PCV20, with a gain of 0.0053 LYs and 0.0045 QALYs per person. The ICER for PCV20 and PPSV23 was 2270 USD/LY and 2677 USD/QALY. CONCLUSIONS: In South Korea, PCV20 is a cost-effective option compared with PPSV23 for adults aged 65 years and older. These cost-effectiveness results provide evidence for decision-making regarding the approval and National Immunization Program implementation of PCV20.

Effectiveness of ten-valent pneumococcal conjugate vaccine on invasive pneumococcal disease among children <2 years old: A prospective population-based study in rural Bangladesh.

The 10-valent pneumococcal conjugate vaccine (PCV10) was introduced in March 2015 in Bangladesh. In this study, we aimed to estimate the impact of PCV10 on invasive pneumococcal disease (IPD) identified by blood cultures and severe pneumonia identified clinically and its effectiveness on invasive disease caused by vaccine serotypes. We conducted population-based surveillance among children aged 2- <24 months between April 2012 through March 2019 in Mirzapur, a rural sub-district of Bangladesh. We compared incidence of IPD and severe pneumonia before (April 2012 to March 2015) and after (April 2015 to March 2019) the introduction of PCV10. Vaccine effectiveness was measured using an indirect cohort analysis of data from four sentinel sites in which PCV10 vaccination status was compared between children with IPD caused by vaccine serotype vs. non-vaccine serotypes. We identified 24 IPD cases by blood culture and 1,704 severe pneumonia hospitalizations during the surveillance period. IPD incidence in under-2-year-old children fell 25 % (95 % CI: -1.2 % to 76 %; p-value = 0.59) from 106 cases per 100,000 child-years at baseline to 79.3 in April 2018- March 2019. Vaccine serotype-IPD incidence was lower (77 % reduction, 95 % CI: -0.45 % to 96 %; p-value = 0.068) in April 2018 - March 2019 than in the pre-vaccine period (85.7 cases to 19.8/100,000 child-years). A significant decline of 54.0 % (95 % CI: 47.0 % to 59.0 %; p-value < 0.001) was observed in hospitalizations due to severe pneumonia. From indirect cohort analysis, the effectiveness of PCV10 against vaccine serotype IPD was 37 % (95 % CI: -141.0 % to 83.5 %; p = 0.5) after the 1st dose and 63.1 % (95 % CI: -3.3 % to 85.9 %, p = 0.0411) after the 2nd or the 3rd dose. This study demonstrates that PCV10 introduction prevented hospitalizations with severe pneumonia and provided individual protection against vaccine serotypes.

Adequate immune responses to vaccines after chemotherapy for leukaemia diagnosed in childhood.

AIM: The survival rate after treatment for childhood leukaemia has greatly improved, but could result in protracted immune deficiency. This study examined the immune status of children after chemotherapy and evaluated their responses to immunisation. METHODS: Subjects who had completed their treatment for acute lymphoblastic leukaemia at The Children's Hospital Reykjavík, Iceland, during 2011-2020 had blood drawn and were then immunised for influenza in October 2021. Blood was drawn again 4 weeks later and their humoral and cellular responses were measured with a haemagglutination inhibition assay and lymphocyte stimulation test. Antibodies to other immunisations were also evaluated. RESULTS: We studied 18 patients (10 male) who had completed their treatment at 3.7-20.3 years of age (mean 9.1), 11-84 months (mean 36.9) before enrolment. Conventional immunological evaluation did not reveal notable abnormalities. The responses to several childhood vaccinations, including the pneumococcal conjugate vaccination, were adequate in most patients. Humoral responses to the influenza vaccine confirmed adequate reactions in all but one patient. Considerable variations were observed in the lymphocyte stimulations tests. CONCLUSION: Most patients reacted adequately to immunisation, especially against annual influenza and Streptococcus pneumoniae, reiterating the usefulness of vaccinations. The most appropriate timing for vaccination after treatment still needs to be determined.

Closing the pneumococcal conjugate vaccine (PCV) introduction gap: an archetype analysis of last-mile countries.

BACKGROUND: Pneumonia remains the leading infectious cause of global childhood deaths, despite the availability of pneumococcal conjugate vaccine (PCV) products and widespread evidence of their safety and efficacy. OBJECTIVE: To map the landscape of countries that are yet to fully include PCV in their National Immunization Programs, we conducted an archetype analysis of country indicators related to barriers and facilitators for PCV decision-making. METHODS: We created a country matrix focused on three key domains - health characteristics, immunisation factors, and policy framework, and identified ten related indicators. We scored countries based on indicator performance and subsequently ranked and grouped them into three archetypes of low-, moderate-, and high-barrier countries with regard to PCV introduction. RESULTS: Our results indicated 39 countries (33 low- and middle-income countries [LMICs] and 6 high-income countries) that are yet to introduce PCV. Among LMICs, 15 countries were classified as 'low-barrier,' indicating factors favourable for PCV introduction such as high immunisation coverage of common childhood vaccines, supportive governments, and substantial disease burden and eligibility for Gavi support. Countries classified in the 'moderate-barrier' (12) and 'high-barrier' (6) archetypes demonstrated adequate capacity in immunisation systems but had competing national priorities and cost barriers that impeded policy decision-making on PCV introduction. CONCLUSIONS: The current health and policy indicator-based categorisation provides an actionable framework to design tailored PCV advocacy within these last-mile countries. Policy approaches emerging from this framework can lead to strengthened decision-making on vaccine introduction and sustained vaccine access that can enhance child survival worldwide.