Strategies for pneumococcal vaccination in older adults in the coming era

Pneumonia, predominantly caused by Streptococcus pneumoniae, remains a leading cause of global mortality. The 23-valent Pneumococcal polysaccharide vaccine (PPSV23) and conjugate vaccines (PCVs) are vital measures to fight against it. This paper discussed the changes in pneumococcal vaccination strategies, particularly for older adults, as vaccine effectiveness and epidemiological patterns shift. While PPSV23 maintains effectiveness against invasive pneumococcal disease (IPD), its effectiveness against pneumococcal pneumonia is declining. Conversely, PCV13 consistently demonstrates effectiveness against both IPD and pneumonia. Consequently, the US Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices recommends using PCVs, notably PCV20 and PCV15, over PPSV23. Japanese studies indicate a change in the efficacy/effectiveness of PPSV23 following PCV introduction in children, likely owing to serotype replacement and herd immunity. Additionally, recent data reveals a plateau in the reduction of PCV13 and PPSV23-covered serotypes, posing a challenge to current strategies. This paper indicates a paradigm shift in pneumonia management, acknowledging its chronic nature and potential to exacerbate other diseases. The future of pneumococcal vaccination lies in broader serotype coverage through PCVs, adapting to serotype changes driven by childhood vaccination programs. Furthermore, continuous research and vaccine development are crucial in this evolving field.

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.

[Pay attention to new evolution trends in the etiology of community-acquired pneumonia in adults]

Over the past two to three decades, the emergence and re-emergence of new infectious diseases, advances in molecular detection techniques of pathogens, antibiotic resistance, changes in population lifestyle and immune status (including vaccination), and other factors have led to new evolutions in the etiology of community-acquired pneumonia (CAP). (1) Although Streptococcus pneumoniae remains a common pathogen of CAP, it is no longer the leading cause in China and the United States. According to the results of 2 multicenter studies in China in the early 21st century, Streptococcus pneumoniae accounted for 10.3% and 12.0% of adult CAP pathogens, respectively, ranking second. A study on key pathogens of adult CAP in nine cities in mainland China from 2014 to 2019 using real-time quantitative PCR and conventional culture on respiratory and blood specimens showed an overall prevalence of Streptococcus pneumoniae of 7.43%, ranking sixth. However, its ranking varied from third to seventh among the nine cities. (2) Challenges and concerns about viruses have increased. National surveillance of acute respiratory tract infections and epidemiology in China from 2009 to 2019 indicated that the positivity rates for viral infections in adult pneumonia was 20.5%. These rates were similar to the results of the CDC's CAP pathogen study in the United States, although the rankings were different (viruses ranked second in China and first in the United States). Over the past 20 years, the emergence of new viral respiratory infections caused by mutant strains or zoonotic strains has significantly increased the challenges and threats posed by viral respiratory infections. (3) The role of Mycoplasma pneumoniae (M pneumoniae) in adult CAP and the need for routine empirical antibiotic coverage are controversial. In addition to the influence of epidemic cycles, the prevalence of M pneumoniae is influenced by factors such as age, season, study design, and detection methods, and geographical distribution is also an important influencing factor. Although M. pneumoniae ranks first among CAP pathogens in mainland China (11.05%), there are significant regional differences. In Beijing, Xi'an, and Changchun M. pneumoniae ranks first, while in Harbin, Nanjing, and Fuzhou it ranks second to sixth. In Wuhan, Shenzhen, and Chengdu M. pneumoniae ranks after the tenth position. Available evidence supports the notion that routine coverage of M. pneumoniae is not necessary for empirical treatment of CAP, except in severe cases. In regions with a high prevalence of M. pneumoniae, the decision to cover atypical pathogens in patients with mild to moderate CAP should be based on local data and individualized. (4) CAP caused by multidrug-resistant bacteria, especially multidrug-resistant Gram-negative bacilli (GNB), has become a concern. According to a systematic review of Chinese literature, Klebsiella pneumoniae accounted for 8.12% of adult CAP patients, ranking fifth, and Pseudomonas aeruginosa accounted for 4.7% (ninth). The China Antimicrobial Resistance Surveillance System (CARSS) reported an average resistance rate of 27.7% for Klebsiella pneumoniae to third-generation cephalosporins and a resistance rate of 10.0% to carbapenems in 2021. The average resistance rate of Pseudomonas aeruginosa to carbapenems was 16.6%. Early empirical treatment should consider predicting the resistance profile using a "locally validated risk factor" scoring system. (5) Co-infections are common but under-reported. The development of non-culture detection techniques over the past 40 years has significantly increased the detection rate of respiratory pathogens, especially viruses, leading to an increasing number of reports of bacterial-viral co-infections in CAP. It has been reported that co-infections account for 39% of severe CAP cases on ventilators in the ICU. Currently, there is inconsistency and confusion regarding the definition and concept of co-infection, the choice of detection techniques, and the differentiation between co-detection and co-infection. Many reports of co-infections in COVID-19 lacked pathogenic evidence, and some even listed "effective antibiotic treatment" as one of the diagnostic criteria for viral-bacterial co-infections, suggesting to some extent an overuse of antibiotics in COVID-19. Due to the diverse etiological spectrum of CAP between regions in the recent years, it is challenging to develop unified guidelines for the management of CAP in large countries. This article provides recommendations for the development of local guidelines for the diagnosis and treatment of CAP.

Unveiling the role of preceding seasonal influenza in the development of bacteremic pneumococcal pneumonia in older adults before the COVID-19 pandemic in Japan

OBJECTIVE

We aimed to investigate the impact of preceding seasonal influenza on the clinical characteristics of adult patients with invasive pneumococcal disease (IPD) in Japan.

METHODS

Data for 1722 adult patients with IPD were analyzed before (2017-2019) and during the COVID-19 pandemic (2020-2022).

RESULTS

The seasonal influenza epidemic disappeared soon after the emergence of the pandemic. Compared with that before the pandemic (66.7%), we observed a lower bacteremic pneumonia proportion in patients with IPD during the pandemic (55.6%). The clinical presentations of IPD cases significantly differed between those with and without preceding influenza. The proportion of bacteremic pneumonia was higher in IPD patients with preceding influenza than in those without in both younger (44.9% vs 84.2%) and older adults (65.5% vs 87.0%) before the pandemic. The case fatality rate was significantly higher in IPD patients with preceding influenza (28.3%) than in those without (15.3%) in older adults before the pandemic (P = 0.020). Male and aging are high risk factors for death in older patients with IPD who had preceding influenza.

CONCLUSION

Our study reveals that preceding seasonal influenza plays a role in the development of bacteremic pneumococcal pneumonia, increasing the risk of death in older adults.

Chronic TNF exposure induces glucocorticoid-like immunosuppression in the alveolar macrophages of aged mice that enhances their susceptibility to pneumonia

Chronic low-grade inflammation, particularly elevated tumor necrosis factor (TNF) levels, occurs due to advanced age and is associated with greater susceptibility to infection. One reason for this is age-dependent macrophage dysfunction (ADMD). Herein, we use the adoptive transfer of alveolar macrophages (AM) from aged mice into the airway of young mice to show that inherent age-related defects in AM were sufficient to increase the susceptibility to Streptococcus pneumoniae, a Gram-positive bacterium and the leading cause of community-acquired pneumonia. MAPK phosphorylation arrays using AM lysates from young and aged wild-type (WT) and TNF knockout (KO) mice revealed multilevel TNF-mediated suppression of kinase activity in aged mice. RNAseq analyses of AM validated the suppression of MAPK signaling as a consequence of TNF during aging. Two regulatory phosphatases that suppress MAPK signaling, Dusp1 and Ptprs, were confirmed to be upregulated with age and as a result of TNF exposure both ex vivo and in vitro. Dusp1 is known to be responsible for glucocorticoid-mediated immune suppression, and dexamethasone treatment increased Dusp1 and Ptprs expression in cells and recapitulated the ADMD phenotype. In young mice, treatment with dexamethasone increased the levels of Dusp1 and Ptprs and their susceptibility to infection. TNF-neutralizing antibody reduced Dusp1 and Ptprs levels in AM from aged mice and reduced pneumonia severity following bacterial challenge. We conclude that chronic exposure to TNF increases the expression of the glucocorticoid-associated MAPK signaling suppressors, Dusp1 and Ptprs, which inhibits AM activation and increases susceptibility to bacterial pneumonia in older adults.

Microbiological findings in patients with community-acquired pneumonia: An analysis using the National Hospital Organization Clinical Data Archives

Although large-scale administrative databases may be useful for studies of infectious diseases, conventional databases lack microbiological data. To illustrate the applicability of the National Hospital Organization Clinical Data Archives, a novel database of electronic medical records in Japan, we conducted a descriptive study of the microbiological findings in patients with community-acquired pneumonia using the database. We identified patients aged ≥18 years who were hospitalized for community-acquired bacterial pneumonia between April 2016 and March 2019. We evaluated the results of bacterial culture and antibacterial susceptibility of specimens obtained on the first day of hospitalization, in addition to patient characteristics, diagnosis codes, and intravenous antibiotics administered. The analysis identified 2200 eligible patients from 15 hospitals. Sulbactam-ampicillin was the most frequently used initial antibiotic (32 %), followed by ceftriaxone (22 %) and tazobactam-piperacillin (19 %). Overall, 56 %, 95 %, 56 %, and 73 % of patients with pathogen-specific diagnosis codes in the database for Streptococcus pneumoniae, Haemophilus influenzae, Klebsiella pneumoniae, and Pseudomonas aeruginosa, respectively, also tested positive for the corresponding pathogen in their sputum or blood cultures. Antibacterial susceptibilities were consistent with a previous report from Japan; 81 % of S. pneumoniae cases were resistant to azithromycin, and 48 % of H. influenzae cases were resistant to ampicillin. These microbiological characteristics warrant the future use of this database for detailed real-world research on infectious diseases.

Clinical and economic burden of invasive pneumococcal disease and noninvasive all-cause pneumonia in hospitalized US adults: A multicenter analysis from 2015 to 2020

OBJECTIVES

To evaluate the clinical and economic outcomes in adults hospitalized with invasive pneumococcal disease (IPD) and noninvasive all-cause pneumonia (ACP) overall and by antimicrobial resistance (AMR) status.

METHODS

Hospitalized adults from the BD Insights Research Database with an ICD10 code for IPD, noninvasive ACP or a positive Streptococcus pneumoniae culture/urine antigen test were included. Descriptive statistics and multivariable analyses were used to evaluate outcomes (in-hospital mortality, length of stay [LOS], cost per admission, and hospital margin [costs - payments]).

RESULTS

The study included 88,182 adult patients at 90 US hospitals (October 2015-February 2020). Most (98.6%) had noninvasive ACP and 40.2% were <65 years old. Of 1450 culture-positive patients, 37.7% had an isolate resistant to ≥1 antibiotic class. Observed mortality, median LOS, cost per admission, and hospital margins were 8.3%, 6 days, $9791, and $11, respectively. Risk factors for mortality included ≥50 years of age, higher risk of pneumococcal disease (based on chronic or immunocompromising conditions), and intensive care unit admission. Patients with IPD had similar mortality rates and hospital margins compared with noninvasive ACP, but greater costs per admission and LOS.

CONCLUSION

IPD and noninvasive ACP are associated with substantial clinical and economic burden across all adult age groups. Expanded pneumococcal vaccination programs may help reduce disease burden and decrease hospital costs.

Impact of respiratory viral infections on nasopharyngeal pneumococcal colonization dynamics in children

PURPOSE OF REVIEW

Prevention of acute respiratory illnesses (ARI) in children is a global health priority, as these remain a leading cause of pediatric morbidity and mortality throughout the world. As new products and strategies to prevent respiratory infections caused by important pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza, respiratory syncytial virus and pneumococcus are advancing, increasing evidence suggests that these and other respiratory viruses and pneumococci may exhibit interactions that are associated with altered colonization and disease dynamics. We aim to review recent data evaluating interactions between respiratory viruses and pneumococci in the upper respiratory tract and their potential impact on pneumococcal colonization patterns and disease outcomes.

RECENT FINDINGS

While interactions between influenza infection and subsequent increased susceptibility and transmissibility of colonizing pneumococci have been widely reported in the literature, emerging evidence suggests that human rhinovirus, SARS-CoV-2, and other viruses may also exhibit interactions with pneumococci and alter pneumococcal colonization patterns. Additionally, colonizing pneumococci may play a role in modifying outcomes associated with respiratory viral infections. Recent evidence suggests that vaccination with pneumococcal conjugate vaccines, and prevention of colonization with pneumococcal serotypes included in these vaccines, may be associated with reducing the risk of subsequent viral infection and the severity of the associated illnesses.

SUMMARY

Understanding the direction and dynamics of viral-pneumococcal interactions may elucidate the potential effects of existing and emerging viral and bacterial vaccines and other preventive strategies on the health impact of these important respiratory pathogens.

Spatio-temporal brain invasion pattern of Streptococcus pneumoniae and dynamic changes in the cellular environment in bacteremia-derived meningitis

Streptococcus pneumoniae (the pneumococcus) is the major cause of bacterial meningitis globally, and pneumococcal meningitis is associated with increased risk of long-term neurological sequelae. These include several sensorimotor functions that are controlled by specific brain regions which, during bacterial meningitis, are damaged by a neuroinflammatory response and the deleterious action of bacterial toxins in the brain. However, little is known about the invasion pattern of the pneumococcus into the brain. Using a bacteremia-derived meningitis mouse model, we combined 3D whole brain imaging with brain microdissection to show that all brain regions were equally affected during disease progression, with the presence of pneumococci closely associated to the microvasculature. In the hippocampus, the invasion provoked microglial activation, while the neurogenic niche showed increased proliferation and migration of neuroblasts. Our results indicate that, even before the outbreak of symptoms, the bacterial load throughout the brain is high and causes neuroinflammation and cell death, a pathological scenario which ultimately leads to a failing regeneration of new neurons.

Knockdown of lncRNA NEAT1 suppresses streptococcus pneumoniae-induced ferroptosis in alveolar epithelial cells by regulating the Nrf2-GPX4 pathway

OBJECTIVES

Streptococcus pneumoniae (SP) is a major cause of community-acquired pneumonia. Ferroptosis pitches in pneumonia. Long noncoding RNA nuclear paraspeckle assembly transcript 1 (lncRNA NEAT1) regulates ferroptosis in various cells. Therefore, this study probed the mechanism of lncRNA NEAT1 on SP-induced ferroptosis in AECs.

METHODS

Serum lncRNA NEAT1 level in 36 streptococcus pneumonia patients were retrospectively detected, with its correlations with inflammatory factor (TNF-α/IL-1β/IL-6) levels analyzed. Human pulmonary alveolar epithelial cells (HPAEpiC) were transfected with sh-NEAT1 and induced by SP. Cell viability was evaluated by CCK-8. Lactate dehydrogenase (LDH) activity was assessed. Iron content, and levels of TNF-α/IL-1β/IL-6/IL-10/lncRNA NEAT1/lipid peroxidation products [malondialdehyde (MDA)/glutathione (GSH)/reactive oxygen species/(ROS)]/ferroptosis-related proteins [Cyclooxgenase 2 (COX2)/recombinant solute carrier family 7 member 11 (SLC7A11)/total nuclear factor erythroid 2-related factor 2 (Nrf2)/cytoplasmic Nrf2 (C-Nrf2)/nuclear Nrf2 (N-Nrf2)/GPX4)] were determined by kit/ELISA/RT-qPCR/kits/Western blot. Nrf2 nuclear translocation was detected by immunofluorescence assay. On top of lncRNA NEAT1 knockdown, SP-induced HPAEpiC were treated with ML385.

RESULTS

Serum lncRNA NEAT1 level was elevated in streptococcus pneumonia patients, and were positively interrelated with TNF-α/IL-1β/IL-6 levels. SP promoted cell HPAEpiC injury and inflammatory response, and up-regulated lncRNA NEAT1 level. LncRNA NEAT1 knockdown suppressed HPAEpiC injury/inflammatory response (reduced LDH activity and TNF-α/IL-1β/IL-6 levels, elevated IL-10) and suppressed ferroptosis (decreased iron/MDA/ROS contents and COX2 level, increased GSH/SLC7A11), facilitated Nrf2 nuclear translocation, and up-regulated GPX4. Nrf2-GPX4 pathway inhibition annulled NEAT1 knockdown-mediated improvement on SP-induced HPAEpiC ferroptosis/injury/inflammatory response.

CONCLUSIONS

LncRNA NEAT1 knockdown suppressed SP-induced HPAEpiC ferroptosis by activating Nrf2-GPX4 pathway, thereby alleviating cell injury and inflammatory response.

IL-10-Mediated Regulation of Microglial Inflammation in Brain Meningitis: Novel Insights and Therapeutic Potential

BACKGROUND

Inflammation is a key pathological process in bacterial meningitis, and the transforming growth factor-beta-activated kinase 1 (TAK1)/nuclear factor-kappa B (NF-κB) pathway is implicated in the activation of microglia and the production of inflammatory factors. Interleukin (IL)-10 is an anti-inflammatory cytokine acting in an autocrine fashion in macrophages to limit inflammatory responses by decreasing the production of pro-inflammatory cytokines. This paper investigates how IL-10 can inhibit microglia activation and reduce the inflammatory response of nervous system diseases.

METHODS

This study used a pneumococcal-induced in Pneumococcal meningitis (PM) C57BL/6 mice and BV-2 cells model of microglial activation, assessing the effects of IL-10 on the TAK1/NF-κB pathway. The impact of IL-10 on microglial autophagy was investigated through western blot and immunofluorescence. The effects of IL-10 were evaluated by examining cellular activation markers and the activity of molecular signaling pathways (such as phosphorylation levels of TAK1 and NF-κB).

RESULTS

Pneumococcus induced the activation of microglia and reduced IL-10. IL-10 inhibited the TAK1/NF-κB pathway, reducing the pneumococcal-induced inflammatory response in microglia. IL-10 ameliorated pneumococcal infection-induced microglial injury by inhibiting autophagy. Animal experiment results also showed that IL-10 inhibited inflammation and autophagy during Pneumococcal meningitis in mice.

CONCLUSION

Our study demonstrates that IL-10 reduces the inflammatory response of microglia by inhibiting the TAK1/NF-κB pathway. Additionally, IL-10 ameliorates pneumococcal infection-induced microglial injury by inhibiting the process of autophagy. These results provide a new theoretical basis and offer new insights for developing strategies to treat bacterial meningitis.

Impaired upper respiratory tract barrier function during postnatal development predisposes to invasive pneumococcal disease

Infants are highly susceptible to invasive respiratory and gastrointestinal infections. To elucidate the age-dependent mechanism(s) that drive bacterial spread from the mucosa, we developed an infant mouse model using the prevalent pediatric respiratory pathogen, Streptococcus pneumoniae (Spn). Despite similar upper respiratory tract (URT) colonization levels, the survival rate of Spn-infected infant mice was significantly decreased compared to adults and corresponded with Spn dissemination to the bloodstream. An increased rate of pneumococcal bacteremia in early life beyond the newborn period was attributed to increased bacterial translocation across the URT barrier. Bacterial dissemination in infant mice was independent of URT monocyte or neutrophil infiltration, phagocyte-derived ROS or RNS, inflammation mediated by toll-like receptor 2 or interleukin 1 receptor signaling, or the pore-forming toxin pneumolysin. Using molecular barcoding of Spn, we found that only a minority of bacterial clones in the nasopharynx disseminated to the blood in infant mice, indicating the absence of robust URT barrier breakdown. Rather, transcriptional profiling of the URT epithelium revealed a failure of infant mice to upregulate genes involved in the tight junction pathway. Expression of many such genes was also decreased in early life in humans. Infant mice also showed increased URT barrier permeability and delayed mucociliary clearance during the first two weeks of life, which corresponded with tighter attachment of bacteria to the respiratory epithelium. Together, these results demonstrate a window of vulnerability during postnatal development when altered mucosal barrier function facilitates bacterial dissemination.

The Unneglectable Disease Burden of Otitis Media Among Children in China: A Systematic Review and Meta-analysis

BACKGROUND

Otitis media (OM) is one of the most commonly diagnosed infections among children yet with obscure disease burden.

METHODS

The literature published from 1980 to 2022 was retrieved in PubMed, Ovid-EMBASE, Web of Science, CNKI, Wanfang and VIP. Literature screening, quality assessment and data extraction were conducted by 2 independent reviewers. Heterogeneity and publication bias were detected by I2 , Egger's and Begg's tests. The data were pooled using the random-effects model. The number of OM cases was estimated by the multiplied model based on pooled results and the 2020 China census data.

RESULTS

A total of 28,378 literatures were identified with 67 finally included for data analysis. The OM incidence among children was 7.89% [95% confidence interval (CI): 5.43%-11.33%] and the prevalence of OM was 5.13% (95% CI: 3.49%-7.49%). The most common pathogen of the OM cases was Streptococcus pneumoniae ( S. pneumoniae ), with a positive rate of 33.52% (95% CI: 26.55%-41.29%). The most common serotypes of S. pneumoniae isolated from OM cases were serotypes 19F, 19A, 6B, 23F and 3, with 85.8% covered by the PCV13. We estimated that there were 8,950,797 (95% CI: 6,080,533-12,928,051) OM cases among under-fives in China in 2020, of which 3,374,451 (95% CI: 1,698,901-6,277,862) cases of OM were caused by S. pneumoniae .

CONCLUSIONS

The burden of OM in China was considerable yet neglected. To date, S. pneumoniae was the most frequently detected bacterial pathogen of OM. Vaccination may be effective to protect young children from OM.

Neighborhood-level disadvantages increase risk for invasive pneumococcal disease

BACKGROUND

Streptococcus pneumoniae (Spn) infection remains common worldwide despite recent vaccine efforts. Invasive pneumococcal disease (IPD) is the most severe form of Spn infection. Known individual risk factors for IPD include male gender and African American race. However, area-level socioeconomic factors have not been assessed. We examined the association of neighborhood-level disadvantages and risk of IPD in a tertiary medical center located in a socioeconomic diverse urban area in the Southeastern United States.

METHODS

Patients hospitalized with culture-confirmed Streptococcus pneumoniae (Spn) infection from 01/01/2010 - 12/31/2019 were identified from electronic health record (EHR). The cohort's demographic and clinical information were obtained from EHR. Patients' residential address was geocoded and matched to 2015 area deprivation index (ADI). The association of ADI and IPD was evaluated using logistic regression after controlling for the demographic information (age, sex, race) and clinical factors (BMI, smoking status, alcoholism, immunosuppressive status, vaccination status, comorbidities).

RESULTS

A total of 268 patients were hospitalized with culture-positive Streptococcus pneumoniae infection and 92 (34.3%) of them had IPD. The analysis showed that higher neighborhood deprivation (ADI in 79-100) was associated with increased risk of developing IPD in younger patients with age less than 65 (p = 0.007) after controlling for the individual demographic information and clinical factors.

CONCLUSIONS

ADI is a risk factor for IPD in younger adults. Community-level socioeconomic risk factors should be considered when developing prevention strategies such as increasing vaccine uptake in high risk population to reduce the disease burden of IPD.

Effects of PCV10 and PCV13 on pneumococcal serotype 6C disease, carriage, and antimicrobial resistance

BACKGROUND

The cross-protection of pneumococcal conjugate vaccines (PCV) against serotype 6C is not clearly documented, although 6C represents a substantial burden of pneumococcal disease in recent years. A systematic review by the World Health Organization that covered studies through 2016 concluded that available data were insufficient to determine if either PCV10 (which contains serotype 6B but not 6A) or PCV13 (containing serotype 6A and 6B) conferred protection against 6C.

METHODS

We performed a systematic review of randomized controlled trials and observational studies published between January 2010 - August 2022 (Medline/Embase), covering the direct, indirect, and overall effect of PCV10 and PCV13 against 6C invasive pneumococcal disease (IPD), non-IPD, nasopharyngeal carriage (NPC), and antimicrobial resistance (AMR).

RESULTS

Of 2548 publications identified, 112 were included. Direct vaccine effectiveness against 6C IPD in children ranged between 70 and 85 % for ≥ 1 dose PCV13 (n = 3 studies), was 94 % in fully PCV13 vaccinated children (n = 2), and -14 % for ≥ 1 dose of PCV10 (n = 1). Compared to PCV7, PCV13 efficacy against 6C NPC in children was 66 % (n = 1). Serotype 6C IPD rates or NPC prevalence declined post-PCV13 in most studies in children (n = 5/6) and almost half of studies in adults (n = 5/11), while it increased post-PCV10 for IPD and non-IPD in all studies (n = 6/6). Changes in AMR prevalence were inconsistent.

CONCLUSIONS

In contrast to PCV10, PCV13 vaccination consistently protected against 6C IPD and NPC in children, and provided some level of indirect protection to adults, supporting that serotype 6A but not 6B provides cross-protection to 6C. Vaccine policy makers and regulators should consider the effects of serotype 6A-containing PCVs against serotype 6C disease in their decisions.

Protective effect of PCV13 against all-cause hospitalized pneumonia in children in Beijing, China: real-world evidence

BACKGROUND

The study evaluated the protective effect of 13-valent pneumococcal polysaccharide conjugate vaccine (PCV13) against all-cause hospitalized pneumonia in children in Beijing.

METHODS

Based on the vaccination record and inpatient medical record database of Beijing, children born in 2017 in Beijing, matched by age, gender, and district of the children with the ratio of 1:4, were selected as the vaccinated and unvaccinated groups according whether if vaccinated with PCV13. The incidence rate and 95 % confidence interval (95 %CI), vaccine effectiveness (VE) and direct medical costs of all-cause hospitalized pneumonia were calculated and compared within the same period of 12 months, 18 months, 24 months and 30 months after the birth of the child.

RESULTS

The decreased incidence rates of all-cause hospitalized pneumonia were observed at the four points in the PCV13 vaccinated group compared to the unvaccinated group, which were significant at the points of 12 months (0.42 % vs. 0.72 %, P = 0.001), 18 months (0.90 % vs. 1.26 %, P = 0.002) and 24 months (1.37 % vs. 1.65 %, P = 0.046). The VE of PCV13 against all-cause hospitalized pneumonia within 12 months was the highest as 41.9 % (95 % CI 19.6 %, 58.0 %), followed by 29.3 % (95 % CI 11.4 %, 43.5 %) within 18 months, 17.1 % (95 % CI 0.3 %, 31.1 %) within 24 months and it almost disappeared within 30 months. The VE of 4-dose vaccination within 18 months and 24 months were 39.9 % (95 % CI 20.3 %, 54.7 %) and 27.2 % (95 % CI 8.6 %, 42.0 %), respectively. The median hospitalization cost of the children in the vaccinated group was higher at the four points but without significance.

CONCLUSIONS

PCV13 had a certain protective effect on all-cause hospitalized pneumonia, and the booster immunization strategy had the best protective effect with great public health significance to enter the immunization program.

Cost-effectiveness of an in-development adult-formulated 21-valent pneumococcal conjugate vaccine in US adults aged 50 years or older

Indirect effects of childhood pneumococcal conjugate vaccines (PCV) have diminished the cost-effectiveness of current adult vaccine recommendations. An in-development adult-formulated 21-valent pneumococcal conjugate vaccine (PCV21) may play a critical role in reducing pneumococcal illness by targeting a larger number of serotypes responsible for adult pneumococcal infections. This study assesses the cost-effectiveness of PCV21 in US adults aged 50 years or older compared with currently recommended pneumococcal vaccines, from both the societal and healthcare perspectives. A Markov model evaluated the lifetime cost-effectiveness of PCV21 (given at age 50 years only, at ages 50/65 years, and risk-based at ages < 65 years plus age-based at age 65 years) compared to no vaccination and to currently recommended pneumococcal vaccines given either as currently recommended or routinely at ages 50/65 years. The analysis was conducted in hypothetical Black and non-Black cohorts aged 50 years or older, with and without considering childhood pneumococcal vaccination indirect effects. Model parameters were based on US data. Parameter uncertainty was assessed using 1-way and probabilistic sensitivity analyses. From the societal perspective, PCV21 at ages 50/65 years compared to PCV21 at age 50 years cost $7,410 per quality adjusted life year (QALY) gained in Black cohort analyses and $85,696/QALY gained in the non-Black cohort; PCV21 at ages 50/65 years had the most favorable public health outcomes. From the healthcare perspective, compared to no vaccination, PCV21 at age 50 years cost $46,213/QALY gained in the Black cohort and $86,629/QALY in non-Blacks. All other strategies were dominated in both cohorts and from both perspectives. When considering childhood pneumococcal vaccination indirect effects, costs of PCV21 at ages 50/65 years remained less than $140,000/QALY gained from the societal perspective in both populations. PCV21 is potentially cost-effective compared to currently approved pneumococcal vaccines in adults aged 50 years or older from both the societal and healthcare perspectives.

Poor association between 13-valent pneumococcal conjugate vaccine-induced serum and mucosal antibody responses with experimental Streptococcus pneumoniae serotype 6B colonisation

BACKGROUND

Pneumococcal carriage is the primary reservoir for transmissionand a prerequisite for invasive pneumococcal disease. Pneumococcal Conjugate Vaccine 13 (PCV13) showed a 62% efficacy in protection against experimental Streptococcus pneumoniae serotype 6B (Spn6B) carriage in a controlled human infection model (CHIM) of healthy Malawian adults. We, therefore, measured humoral responses to experimental challenge and PCV-13 vaccination and determined the association with protection against pneumococcal carriage.

METHODS

We vaccinated 204 young, healthy Malawian adults with PCV13 or placebo and nasally inoculated them with Spn6B at least four weeks post-vaccination to establish carriage. We collected peripheral blood and nasal lining fluid at baseline, 4 weeks post-vaccination (7 days pre-inoculation), 2, 7, 14 and > 1 year post-inoculation. We measured the concentration of anti-serotype 6B Capsular Polysaccharide (CPS) Immunoglobulin G (IgG) and IgA antibodies in serum and nasal lining fluid using the World Health Organization (WHO) standardised enzyme-linked immunosorbent assay (ELISA).

RESULTS

PCV13-vaccinated adults had higher serum IgG and nasal IgG/IgA anti-Spn6B CPS-specific binding antibodies than placebo recipients 4 to 6 weeks post-vaccination, which persisted for at least a year after vaccination. Nasal challenge with Spn6B did not significantly alter serum or nasal anti-CPS IgG binding antibody titers with or without experimental pneumococcal carriage. Pre-challenge titers of PCV13-induced serum IgG and nasal IgG/IgA anti-Spn6B CPS binding antibodies did not significantly differ between those that got experimentally colonised by Spn6B compared to those that did not.

CONCLUSION

This study demonstrates that despite high PCV13 efficacy against experimental Spn6B carriage in young, healthy Malawian adults, robust vaccine-induced systemic and mucosal anti-Spn6B CPS binding antibodies did not directly relate to protection.

Uptake of pneumococcal vaccines in older Australian adults before and after universal public funding of PCV13

BACKGROUND

In 2020 Australia changed the funded universal older adult pneumococcal vaccination program from use of the 23-valent pneumococcal polysaccharide vaccine (PPV23) at age 65 to the 13-valent pneumococcal conjugate vaccine (PCV13) at age 70 years. We investigated uptake of both PCV13 and PPV23 in older adults before and after the program change.

METHODS

We analysed a national dataset of records of patients attending general practices (GPs). We included regular attendees aged 65 or above in 2020. Cumulative uptake of PCV13 and monthly uptake of PPV23 was compared for the two periods before (January 2019 to June 2020) and after (July 2020 to May 2021) the program change on 1 July 2020, by age groups and presence of comorbid conditions.

RESULTS

Our study included data from 192,508 patients (mean age in 2020: 75.1 years, 54.2 % female, 46.1 % with at least one comorbidity). Before July 2020, for all adults regardless of underlying comorbidities, the cumulative uptake of PCV13 was < 1 % but by May 2021, eleven months after the program changes, cumulative uptake of PCV13 had increased among those aged 70-79 years (without comorbidity: 16.3 %; with comorbidity: 21.1 %) and 80 + years (without comorbidity: 13.5 %; with comorbidity: 17.7 %), but not among those aged 65-69 years (without comorbidity: 1.3 %; with comorbidity: 3 %). Monthly uptake of PPV23 dropped following the program change across all age groups.

CONCLUSIONS

Changes in uptake of PCV13 and PPV23 among those aged 70 + years were consistent with program changes. However, PCV13 uptake was still substantially lower in individuals aged 65-69 years overall and in those with comorbidities.

Streptococcus pneumoniae as a colonizing agent of the Nasopharynx - Oropharynx in adults: A systematic review and meta-analysis

BACKGROUND

Streptococcus pneumoniae (Spn) is a commensal pathogen that usually colonizes the upper respiratory tract of children. Likewise, Spn colonization has been considered a critical factor in the development of pneumococcal invasive disease. However, Spn prevalence in adults remains unclear. This study performs a systematic review and meta-analysis to explore the prevalence of Spn Nasopharynx - Oropharynx Colonization (NOC) in adults.

METHODS

A Systematic review of scientific databases was utilized to identify eligible studies that follow strict selection criteria. Subsequently, a meta-analysis was conducted to establish NOC prevalence in adults (≥18 years old). The heterogeneity and sensitivity analyses were assessed using the microorganism identification technique, sample type, and age subgroups.

RESULTS

Initial selection includes 69 studies, with 37 selected for the meta-analysis, involving 23,724 individuals. The overall prevalence (95 % CI) of Spn NOC among adults was 6 % (5-9). The subgroup analysis revealed that young adults (YA), 18-64 years old, had a prevalence of 10 %, whereas older adults (OA), ≥65 years old, had a prevalence of 2 %. The identification of Spn NOC may vary depending on the method of diagnosis used. High heterogeneity (I2 > 90 %) was observed but diminished to 70 % when the analysis was restricted to oropharyngeal swabs as an identification method. Furthermore, heterogeneity decreased to 58 % when exclusively employing traditional culture as the identification method.

CONCLUSIONS

This study found a low prevalence of Spn NOC in adults. Notably, the prevalence of Spn NOC was higher in younger adults than in older adults. It is essential to highlight a significant heterogeneity among studies, which indicates there is no standardized method of Spn NOC identification.

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.

The host transcriptional response to superinfection by influenza A virus and Streptococcus pneumoniae

Secondary bacterial challenges during influenza virus infection "superinfection") cause excessive mortality and hospitalization. Here, we present a longitudinal study of bulk gene expression changes in murine lungs during superinfection, with an initial influenza A virus infection and a subsequent Streptococcus pneumoniae infection. In addition to the well-characterized impairment of the host response, we identified superinfection-specific alterations in the global transcriptional program that are linked to the host's ability to resist the pathogens. Particularly, whereas superinfected mice manifested an excessive rapid induction of the resistance-to-infection program, there was a substantial tissue-level rewiring of this program: upon superinfection, interferon-regulated genes were switched from positive to negative correlations with the host's resistance state, whereas genes of fatty acid metabolism switched from negative to positive correlations with resistance states. Thus, the transcriptional resistance state in superinfection is reprogrammed toward repressed interferon signaling and induced fatty acid metabolism. Our findings suggest new insights into a tissue-level remodeling of the host defense upon superinfection, providing promising targets for future therapeutic interventions.

IMPORTANCE

Secondary bacterial infections are the most frequent complications during influenza A virus (IAV) pandemic outbreaks, contributing to excessive morbidity and mortality in the human population. Most IAV-related deaths are attributed to Streptococcus pneumoniae (SP) infections, which usually begin within the first week of IAV infection in the respiratory tracts. Here, we focused on longitudinal transcriptional responses during a superinfection model consisting of an SP infection that follows an initial IAV infection, comparing superinfection to an IAV-only infection, an SP-only infection, and control treatments. Our longitudinal data allowed a fine analysis of gene expression changes during superinfection. For instance, we found that superinfected mice exhibited rapid gene expression induction or reduction within the first 12 h after encountering the second pathogen. Cell proliferation and immune response activation processes were upregulated, while endothelial processes, vasculogenesis, and angiogenesis were downregulated, providing promising targets for future therapeutic interventions. We further analyzed the longitudinal transcriptional responses in the context of a previously defined spectrum of the host's resistance state, revealing superinfection-specific reprogramming of resistance states, such as reprogramming of fatty acid metabolism and interferon signaling. The reprogrammed functions are compelling new targets for switching the pathogenic superinfection state into a single-infection state.