Effectiveness of 23-Valent Pneumococcal Polysaccharide Vaccine against Invasive Pneumococcal Disease in Adults, Japan, 2013-2017

Management of the Diagnosis and Treatment of Pneumonia in an Aging Society

The diagnosis of pneumonia is based on respiratory and systemic symptoms, blood test findings, chest radiographic findings, and the condition of the patient. Physicians in aging or aged societies such as Japan carefully evaluate the comprehensive situation of each pneumonia patient with adequate evaluation and treatment according to "the Japanese Respiratory Society (JRS) guidelines for the management of pneumonia in adults in 2024." These guidelines categorize pneumonia into three types: community-acquired, nursing- and healthcare-associated, and hospital-acquired. The selection of treatment settings and empirical antimicrobials for pneumonia depends on pneumonia classification, severity, and risk factors for potential drug-resistant bacteria, as outlined in the JRS guidelines. This review concisely describes the historical evolution of the diagnosis and treatment of pneumonia in elderly societies, including aspiration pneumonia, from multiple perspectives. In addition, it explores the differential diagnoses when antimicrobial treatment for pneumonia is ineffective, highlighting key aspects through chest radiography and computed tomography.

Mortality reduction with 23-valent pneumococcal polysaccharide vaccine: a systematic review and meta-analysis

BACKGROUND

Pneumococcal disease, caused by Streptococcus pneumoniae, imposes a significant global health burden, particularly affecting vulnerable groups such as the elderly and immunocompromised. The 23-valent pneumococcal polysaccharide vaccine (PPV23) is designed to protect against 23 serotypes of Streptococcus pneumoniae. However, there is ongoing debate about its effectiveness in reducing all-cause mortality. This systematic review and meta-analysis aimed to evaluate the efficacy of PPV23 in reducing all-cause and pneumonia-related mortality among adults.

METHODS

A systematic search was conducted across PubMed, Embase, and Web of Science, focusing on studies that evaluated the mortality outcomes of adults vaccinated with PPV23 compared to non-vaccinated adults. Both randomized controlled trials (RCTs) and observational studies were included, while case reports, case series, and non-human studies were excluded. Data extraction and quality assessment were facilitated by Nested Knowledge software, using the Newcastle-Ottawa Scale for observational studies and the Cochrane Risk of Bias tool for RCTs.

RESULTS

The search yielded 826 records, with 19 studies meeting the inclusion criteria. The pooled analysis of four RCTs showed no significant reduction in all-cause mortality (RR = 1.030; 95% CI: 0.945, 1.122). However, analysis of pneumonia-related mortality across various studies indicated a significant reduction (HR = 0.504; 95% CI: 0.316, 0.693). Moderate to high heterogeneity was noted in mortality studies, and a potential publication bias was identified.

CONCLUSION

The findings suggest that while PPV23 may not significantly reduce all-cause mortality, it is effective in reducing pneumonia-related mortality among adults, particularly in those at higher risk. These results support the continued use of PPV23 in targeted adult populations, emphasizing the need for more primary studies to explore its effectiveness across diverse groups.

Secondary Immunodeficiency and Vaccine Response in Rheumatoid and Psoriatic Arthritis on Immunosuppressive Medicines

Background Rheumatoid arthritis and psoriatic arthritis patients have dysregulated immune system parameters that may increase infection risk at baseline. In addition, treatment of these conditions with immunosuppressive medications may lead to the development of secondary immunodeficiency (SID). Our objective was to assess SID in a cohort on immunosuppressive medications. We hypothesized that SID is clinically detectable by assessing immune parameters and polysaccharide and protein-based vaccination responses. Methodology A prospective cohort study of 42 subjects on immunosuppressive medications was assessed. Analysis included immunoglobulin levels, lymphocyte subsets, and two-step response to diphtheria, tetanus, and 23-valent Streptococcus pneumoniae vaccinations. Exclusions included primary immunodeficiency, malignancy, pregnancy, neutropenia, immunoglobulin replacement, prior B-cell-depleting medication or chemotherapy, use of non-immunosuppressive medication, or recent use of glucocorticoids. Suboptimal vaccine response was defined as an abnormal response based on standard criteria for each vaccine. Results Low IgM levels (below 50 mg/dL) occurred in seven (17%) subjects and IgG (below 650 mg/dL) in three (7%) subjects. Impaired lymphocyte subsets were uncommon. In total, 33 (78%) subjects completed the two-step vaccination assessment. Overall, 29 of 33 (88%) subjects demonstrated suboptimal response to pneumococcal vaccination, 10 (30%) demonstrated suboptimal response to diphtheria, and four (12%) to tetanus. Two (6%) subjects demonstrated suboptimal response to all vaccinations. Finally, 31 (94%) subjects demonstrated suboptimal response to at least one vaccination. Conclusions SID may develop, is clinically detectable, and most notably demonstrated in suboptimal responses to polysaccharide vaccinations, especially against S. pneumoniae.

Follow-Up Study of Effectiveness of 23-Valent Pneumococcal Polysaccharide Vaccine Against All-Type and Serotype-Specific Invasive Pneumococcal Disease, Denmark

As a follow-up to a previous study, we investigated vaccine effectiveness (VE) of 23-valent pneumococcal polysaccharide vaccine (PPSV23) against invasive pneumococcal disease (IPD) among 1,254,498 persons >65 years of age as part of a vaccination program in Denmark during April 2020-January 2023. We assessed VE by using a Cox regression model and adjusted for age, sex, and underlying conditions. Using nationwide data, we estimated a VE of PPSV23 against all-type IPD of 32% and against PPSV23-serotype IPD of 41%. Because this follow-up study had more statistical power than the original study, we also estimated VE against IPD caused by PPSV23-serotypes excluding serotype 3; serotype 3; serotype 8; serotype 22F; PPSV23 non-PCV15 serotypes; PPSV23 non-PCV20 serotypes; and IPD over time. Our findings suggest PPSV23 vaccination can protect persons >65 years of age against IPD caused by all serotypes or serotype groupings, except serotype 3.

Systematic Review and Meta-Analysis of the Efficacy and Effectiveness of Pneumococcal Vaccines in Adults

New pneumococcal conjugate vaccines (PCVs), 15- and 20-valent (PCV15 and PCV20), have been licensed for use among U.S. adults based on safety and immunogenicity data compared with the previously recommended 13-valent PCV (PCV13) and 23-valent pneumococcal polysaccharide vaccines (PPSV23). We conducted a systematic review of the literature on PCV13 and PPSV23 efficacy (randomized controlled trials [RCTs]) or effectiveness (observational studies) against vaccine type (PCV13 type or PPSV23 type, respectively), invasive pneumococcal disease (IPD), and pneumococcal pneumonia (PP) in adults. We utilized the search strategy from a previous systematic review of the literature published during the period from January 2016 to April 2019, and updated the search through March 2022. The certainty of evidence was assessed using the Cochrane risk-of-bias 2.0 tool and the Newcastle-Ottawa scale. When feasible, meta-analyses were conducted. Of the 5085 titles identified, 19 studies were included. One RCT reported PCV13 efficacy of 75% (PCV13-type IPD) and 45% (PCV13-type PP). Three studies each reported PCV13 effectiveness against PCV13-type IPD (range 47% to 68%) and against PCV13-type PP (range 38% to 68%). The pooled PPSV23 effectiveness was 45% (95% CI: 37%, 51%) against PPSV23-type IPD (nine studies) and 18% (95% CI: -4%, 35%) against PPSV23-type PP (five studies). Despite the heterogeneity across studies, our findings suggest that PCV13 and PPSV23 protect against VT-IPD and VT-PP in adults.

Vaccine effectiveness of the pneumococcal polysaccharide and conjugated vaccines in elderly and high-risk populations in preventing invasive pneumococcal disease: a systematic search and meta-analysis

BACKGROUND

Invasive pneumococcal disease (IPD) is a major cause of morbidity and mortality globally. However, the literature on the vaccine effectiveness (VE) of 23-valent polysaccharide vaccine (PPV23) and 13-valent conjugated vaccine (PCV13) against IPD in adults is sparse. The aim was to summarize the available evidence on the VE of the PPV23 and the PCV13 in elderly individuals against IPD and to investigate how age and comorbidities influence VE against IPD.

METHODS

A systematic search was conducted in Medline and Embase in February 2021. We used combinations of terms related to PPV23, PCV13, elderly, high-risk populations, and IPD. Eligible articles published since 2010 were included. Two authors reviewed and extracted data.

RESULTS

Eight studies met the inclusion criteria for PPV23. The meta-analysis showed a reduced OR for all-type IPD with the use of PPV23 vaccine compared with unvaccinated controls (OR 0.69; 95%CI 0.54, 0.88) and a reduced OR for vaccine-type IPD compared with non-vaccine type IPD (0.69; 95%CI 0.63, 0.76). VE against vaccine-type IPD ranged from 28% to 54.1% for individuals aged 65-79 and from 7.5% to 34% for those aged ≥80-85 years. Most studies found a lower VE of PPV23 in populations with comorbidities and in immunocompromised populations compared with the VE for individuals without comorbidities.One study met the inclusion criteria for PCV13. The vaccine efficacy of PCV13 against IPD in individuals aged ≥65 was 75.0% (95% CI, 41.4 to 90.8).

CONCLUSION

The results from this review show a reduction of IPD in elderly and high-risk populations vaccinated with PPV23 and PCV13. The protective effect may be lower in elderly individuals aged >80 and in individuals with comorbidities. However, the literature is sparse; large-scale prospective studies are required to evaluate the VE of PPV23 and PCV13 vaccination in adults against IPD.

Cost-effectiveness analyses of 15- and 20-valent pneumococcal conjugate vaccines for Japanese elderly

BACKGROUND

Despite the 23-valent pneumococcal polysaccharide vaccine (PPSV23) vaccination programme implementation, pneumococcal disease (PD) remains an important cause of morbidity and mortality among the elderly in Japan, particularly since childhood pneumococcal conjugate vaccine (PCV) vaccination programme continues to alter the serotype PD distribution among the elderly. Recently, in the United States, PCV15/PCV20 were recommended for adults aged ≥ 65 years and those aged 19-64 years with certain underlying conditions. In Japan, PCV15 is under the approval application process and PCV20 undergoing clinical trials, which has warranted the need in evaluating their value for money.

METHODS

We conducted cost-effectiveness analyses with Markov model and calculated incremental cost-effectiveness ratios of PCV15/PCV20 vaccination programme compared to status quo from payers' perspective. Transition probabilities and utility weights in estimating quality-adjusted life-year (QALY), and disease treatment costs were either estimated or obtained from literature. To reflect the situation of COVID-19 pandemic, epidemiological data from 2020 and beyond were used.

RESULTS

Compared to the current vaccination programme, PCV20 vaccination programme gained more QALYs with less cost, while PCV15 vaccination programme cost ¥35,020 (US$318, US$1 = ¥110) to gain an additional QALY. Replacing PPSV23 vaccination programme with PCV20 vaccination programme is cost-saving. One-way sensitivity analyses revealed that lower VE limits of PCVs against non-bacteremic pneumonia (NBP) have large impact to change the result from PCV20 vaccination programme dominated PPSV23 vaccination programme to PPSV23 vaccination programme dominated PCV20 vaccination programme.

CONCLUSION

In the COVID-19 era, replacing current PPSV23 with a single-dose PCV15- or PCV20 immunisation programme for 65-year-old adults in Japan is highly cost-effective, while the PCV 20 vaccination programme was observed to be more favourable.

Impact of national pneumococcal vaccination program on invasive pneumococcal diseases in South Korea

Following the introduction of pneumococcal conjugate vaccines (PCVs), the rate of invasive pneumococcal disease (IPD) declined, however, IPDs replaced by serotypes that are not included in the vaccine have emerged. We describe the epidemiology of IPD in South Korea over a 4.5-year period, encompassing the impact following introduction of PCV10/13 and PPSV23 into the public immunization program, and assess serotype dynamics in pediatric and adult population. This was a nationwide, retrospective review of surveillance of all IPD cases in Korea between September 2014 to December 2019. We analyzed VT13 (serotypes included in 13-valent conjugate vaccine) and NVT (nonvaccine type) cases by age, sex, IPD type, vaccination status, and deaths. A total of 893 cases with serotype data were included; 306 (34%) VT13 cases and 587 (66%) NVT cases. Serotype 3 (n = 155) was the most common VT13 serotype, followed by serotypes 19A (n = 70) and 14 (n = 28). Among the NVTs, serotype 10A (n = 74) was the most common serotype, followed by serotypes 23A (n = 60) and 34 (n = 58). Persons who had PCV13 vaccination were at lower risk (aOR = 0.11, 95% CI 0.02–0.73, P = 0.022) of death compared to unvaccinated persons. Introduction of PCV10/13 and PPSV23 vaccination program has had different impacts on the serotype-specific IPD across age groups. The most common serotypes included serotypes 3 and 19A (VT13), and 10A, 23A, and 34 (NVT). Our findings suggest continued monitoring in the midst of new vaccine development, and a need to develop novel strategies to mitigate the IPDs from emerging pneumococcal serotypes.

Long-term impact of pneumococcal conjugate vaccines for children on adult pneumococcal pneumonia in Japan: Two multicenter observational studies from 2011 to 2020

BACKGROUND

Pediatric pneumococcal conjugate vaccines (PCVs) introduction has directly and indirectly reduced pneumococcal pneumonia and invasive disease caused by PCV-covered serotypes among children and adults globally. In Japan, both PCV7 and PCV13 were introduced into the national immunization program (NIP) for children in 2013. However, the long-term impact of PCV use in children on adult pneumococcal pneumonia in Japan remains unclear.

METHODS

We assessed serotypes isolated from adult pneumococcal pneumonia patients (in- and outpatients) in two multicenter observational studies in Japan: 2011-2014 and 2016-2020. The latter study period was divided into two periods to evaluate changes after PCV introduction in children. The Quellung reaction was used to determine serotypes. We evaluated trends of individual and vaccine-covered serotypes over three periods and assessed the difference in changes by patient group before and after the introduction of pediatric PCVs.

RESULTS

A total of 650 patients were enrolled: 224, 322, and 104 in 2011-2014, 2016-2017, and 2018-2020, respectively. The median age was 73 years; 59.7% (388/650) were male; 86.9% (565/650) had comorbidities; and 10.2% (66/650) were nursing-home residents. The proportion of PCV13 serotypes decreased from 52.7% in 2011-2014 to 30.4% in 2016-2017 (p <0.001) after PCV13 introduction for children. However, PCV13, PCV15, and PCV20 serotypes still accounted for 38.5, 43.3, and 59.6% of total pneumococcal pneumonia in 2018-2020, respectively. Decline of PCV13 serotypes was more marked in patients aged ≥65 (-23.5%; p <0.001) than those aged <65 (-12.3%; p = 0.104) from 2011-2014 to 2016-2020. The proportion of PPSV23 non-PCV13 serotypes didn't change over time.

CONCLUSIONS

The proportion of adult pneumococcal pneumonia caused by PCV13 serotypes in Japan declined after pediatric PCVs introduction into NIP, possibly due to indirect effects of pediatric PCVs. However, use of new PCVs in Japanese adults may potentially prevent additional pneumococcal pneumonia cases. Now, pneumococcal vaccination strategy for older adults requires discussion.

Dynamic changes in clinical characteristics and serotype distribution of invasive pneumococcal disease among adults in Japan after introduction of the pediatric 13-valent pneumococcal conjugate vaccine in 2013-2019

Nationwide population-based surveillance for invasive pneumococcal disease (IPD) is being conducted in few Asian countries. We aimed to evaluate the clinical characteristics and serotype distribution among Japanese adult patients with IPD after introduction of the pediatric 13-valent pneumococcal conjugate vaccine (PCV13) in 2013. IPD surveillance was conducted among adults between 2013 and 2019, and 1,995 patients were analyzed by time period (early, 2013-2015; middle, 2016-2017; late, 2018-2019). We found that the period of 2018-2019 was independently associated with a lower risk of fatal outcome, compared with the period of 2013-2015. The proportion of those with serotype PCV13-nonPCV7 decreased significantly in patients aged 15-64 years and in those aged ≥ 65 years within 3 years after the introduction of pediatric PCV13. By contrast, the proportion of those with nonvaccine serotype increased significantly in those aged ≥ 65 years, but not in those aged 15-64 years. No significant change was found in the proportion of 23-valent polysaccharide pneumococcal vaccine (PPSV23)-nonPCV13 in both of adults aged 15-64 years and ≥ 65 years. The proportions of PCV15-, PCV20- and PCV24-covered serotypes were 38%, 56% and 58% in adult patients with IPD aged ≥ 65 years during the late period. Our data on the serotype distribution support an indirect effect from pediatric PCV13 use among adults, and afford a basis for estimates of protection against IPD by vaccination with newly developed PCVs in older adults in Japan.

23-Valent Pneumococcal Polysaccharide Vaccination Does Not Prevent Community-Acquired Pneumonia Hospitalizations Due to Vaccine-Type Streptococcus pneumoniae

Controversy exists regarding the clinical effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) for the prevention of serotype-specific community-acquired pneumonia (CAP). The objective of this study was to define the effectiveness of PPSV23 for the prevention of CAP hospitalizations due to vaccine-contained serotypes. This secondary analysis was a nested case–control, test-negative study design of adult patients hospitalized for CAP between 1 June 2014 and 31 March 2017. Cases included patients with CAP due to a S. pneumoniae serotype contained in the PPSV23. Urinary antigen detection of the 23 serotypes was performed. In the study, PPSV23 vaccination alone and no other pneumococcal vaccination was the primary exposure of interest. Vaccine effectiveness was calculated as (1-OR) × 100. Adjusted estimates were obtained from a logistic regression model that controlled for confounding variables. A total of 3686 patients were included in the analysis. The PPSV23 vaccination was documented in 608 (16%) patients, and the PPSV23-serotype CAP was detected in 48 (8%) PPSV23-vaccinated patients and in 288 (9%) non-vaccinated patients. Unadjusted vaccine effectiveness for preventing PPSV23-serotype CAP was 17% (95% CI: −13% to 40%). Adjusted estimates for preventing PPSV23-serotype CAP was 14% (95% CI: −17% to 38%). In this study, PPSV23 vaccination offered no protection against PPSV23-serotype CAP hospitalization in adults. This is the first PPSV23 vaccine effectiveness study from United States that utilized a urinary antigen detection assay as the main method for S. pneumoniae serotyping. This study highlights the need for more effective vaccines in the prevention of hospitalization due to S. pneumoniae CAP.

Whole-genome analysis-based phylogeographic investigation of Streptococcus pneumoniae serotype 19A sequence type 320 isolates in Japan

After the introduction of the seven-valent pneumococcal conjugate vaccine, the global spread of multidrug-resistant serotype 19A-sequence type 320 (ST320) strains of Streptococcus pneumoniae became a public health concern. In Japan, the main genotype of serotype 19A was ST3111, and the identification rate of ST320 was low. Although the isolates were sporadically detected in both adults and children, their origin remains unknown. Thus, by combining pneumococcal isolates collected in three nationwide pneumococcal surveillance studies conducted in Japan between 2008 and 2020, we analyzed 56 serotype 19A-ST320 isolates along with 931 global isolates, using whole-genome sequencing to uncover the transmission route of the globally distributed clone in Japan. The clone was frequently detected in Okinawa Prefecture, where the United States returned to Japan in 1972. Phylogenetic analysis demonstrated that the isolates from Japan were genetically related to those from the United States; therefore, the common ancestor may have originated in the United States. In addition, Bayesian analysis suggested that the time to the most recent common ancestor of the isolates from Japan and the U.S. was approximately the 1990s to 2000, suggesting the possibility that the common ancestor could have already spread in the United States before the Taiwan 19F-14 isolate was first identified in a Taiwanese hospital in 1997. The phylogeographical analysis supported the transmission of the clone from the United States to Japan, but the analysis could be influenced by sampling bias. These results suggested the possibility that the serotype 19A-ST320 clone had already spread in the United States before being imported into Japan.

Distribution and Variation of Serotypes and Pneumococcal Surface Protein A Clades of Streptococcus pneumoniae Strains Isolated From Adult Patients With Invasive Pneumococcal Disease in Japan

Pneumococcal surface protein A (PspA) is a surface protein of Streptococcus pneumoniae that may be a candidate antigen for new pneumococcal vaccines. This study investigates the distribution of PspA clades of the causative strains of adult invasive pneumococcal disease (IPD) in Japan. Of the 1,939 strains isolated from cases of adult IPD during 2014–2019, the PspA clades of 1,932 (99.6%) strains were determined, and no pspA was detected in the remaining 7 strains (0.4%). PspA clades 1–6 were detected in 786 (40.5%), 291 (15.0%), 443 (22.8%), 369 (19.0%), 33 (1.7%), and 6 (0.3%) strains, respectively. New PspA clades (0.2%) were identified in two non-typeable and two serotype 35B pneumococci. The proportions of clade 1 and clade 2 showed significantly decreased and increased trends, respectively. Furthermore, the PspA clade of pneumococcal strains was partially serotype- and sequence type-dependent. The majority of strains belonging to serotypes contained in both the 13-valent pneumococcal conjugate vaccine (PCV13) and the 23-valent pneumococcal polysaccharide vaccine (PPSV23) belonged to PspA clades 1 or 3. In contrast, the distribution of clades in non-vaccine serotypes was wider than that of vaccine serotype pneumococci. Our findings demonstrate that almost all pneumococcal strains from adult IPD express PspA clades 1–4, especially for non-vaccine serotypes. These results may be useful for the development of a new pneumococcal vaccine with PspA.

Efficacy and effectiveness of a 23-valent polysaccharide vaccine against invasive and noninvasive pneumococcal disease and related outcomes: a review of available evidence

Introduction: Routine pneumococcal vaccination for adults aged ≥60 or ≥65 years and those with underlying at-risk and high-risk conditions is recommended in many countries. However, studies estimating the effectiveness of 23-valent pneumococcal polysaccharide vaccine (PPSV23) have revealed mixed results, partly due to variability in study design and endpoints used to assess outcomes.Areas covered: The authors conducted a literature review of independently randomized trials and real-world studies published from 2010 to 2020 that assessed the effectiveness and efficacy of PPSV23 against vaccine-type or any-serotype invasive and noninvasive pneumococcal disease in adults aged ≥60 years. The authors also evaluated differences in study design that may contribute to the heterogeneity of available evidence.Expert opinion: Policy decisions regarding the inclusion of vaccines into national immunization plans should consider study quality and limitations. This review shows that PPSV23 is effective against vaccine-type invasive pneumococcal disease and vaccine-type pneumococcal pneumonia and can lower the burden of vaccine-type pneumococcal pneumonia. PPSV23-conferred protection may be lower in adults aged ≥75 years, those with certain underlying conditions, and individuals who were vaccinated >5 years before disease onset. This is an important finding that supports the benefit of PPSV23 vaccination for older adults.