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

The impact and cost-effectiveness of pneumococcal immunisation strategies for the elderly in England

Pneumococcal disease, presenting as invasive pneumococcal disease (IPD) or community-acquired pneumonia (CAP) is an important cause of illness and hospitalisation in the elderly. To reduce pneumococcal burden, since 2003, 65-year-olds in England have been offered a 23-valent pneumococcal polysaccharide vaccine (PPV23). This study compares the impact and cost-effectiveness (CE) of vaccination with the existing PPV23 vaccine to the new 15-and 20-valent pneumococcal conjugate vaccines (PCV15 and PCV20), targeting adults aged 65 or 75 years old. We developed a static Markov model for immunisation against pneumococcal disease, capturing different vaccine effectiveness and immunity waning assumptions, projecting the number of IPD/CAP cases averted over the thirty years following vaccination. Using an economic model and probabilistic sensitivity analysis we evaluated the CE of the different immunisation strategies at current vaccine list prices and the willingness-to-pay at a median threshold of £20,000/QALY and an uncertainty threshold of 90% of simulations below £30,000/QALY. PCV20 averted more IPD and CAP cases than PCV15 or PPV23 over the thirty years following vaccination: 353(360), 145(159) and 150(174) IPD and 581(673), 259(485) and 212(235) CAP cases at a vaccination age of 65(75) under base vaccine effectiveness assumptions. At the listed prices of PCV20 and PPV23 vaccines as of May 2023, both vaccines were cost-effective when vaccinating 65- or 75-year-olds with an ICER threshold of £20,000 per QALY. To achieve the same cost-effectiveness as PPV23, the additional cost of PCV20 should be less than £44(£91) at an ICER threshold of £20,000/QALY (£30,000/QALY) if vaccination age is 65 (or £54(£103) if vaccination age is increased to 75). We showed that both PPV23 and PCV20 were likely to be cost-effective. PCV20 was likely to avert more cases of pneumococcal disease in elderly adults in England than the current PPV23 vaccine, given input assumptions of a higher vaccine effectiveness and slower waning for PCV20.

Immunogenicity and safety of a 14-valent pneumococcal polysaccharide conjugate vaccine (PNEUBEVAX 14™) administered to 6-8 weeks old healthy Indian Infants: A single blind, randomized, active-controlled, Phase-III study

BACKGROUND

Introduction of pneumococcal conjugate vaccines (PCVs) reduced the number of cases of pneumococcal disease (PD). However, there is an increase in clinical and economic burden of PD from serotypes that are not part of the existing pneumococcal vaccines, particularly impacting pediatric and elder population. In addition, the regions where the PCV is not available, the disease burden remains high. In this study, immunogenicity and safety of the BE's 14-valent PCV (PNEUBEVAX 14™; BE-PCV-14) containing two additional epidemiologically important serotypes (22F and 33F) was evaluated in infants in comparison to licensed vaccine, Prevenar-13 (PCV-13).

METHODS

This is a pivotal phase-3 single blind randomized active-controlled study conducted at 12 sites across India in 6-8 weeks old healthy infants at 6-10-14 weeks dosing schedule to assess immunogenic non-inferiority and safety of a candidate BE-PCV-14. In total, 1290 infants were equally randomized to receive either BE-PCV-14 or PCV-13. Solicited local reactions and systemic events, adverse events (AEs), serious AEs (SAEs), and medically attended AEs (MAAEs) were recorded. Immunogenicity was assessed by measuring anti-PnCPS (anti-pneumococcal capsular polysaccharide) IgG concentration and functional antibody titers through opsonophagocytic activity (OPA), one month after completing three dose schedule. Cross protection to serotype 6A offered by serotype 6B was also assessed in this study.

FINDINGS

The safety profile of BE-PCV-14 was comparable to PCV-13 vaccine. Majority of reported AEs were mild in nature. No severe or serious AEs were reported in both the treatment groups. For the twelve common serotypes and for the additional serotypes (22F and 33F) in BE-PCV-14, NI criteria was demonstrated as defined by WHO TRS-977. Primary immunogenicity endpoint was met in terms of IgG immune responses for all 14 serotypesof BE-PCV-14. Moreover, a significant proportion of subjects (69%) seroconverted against serotype 6A, even though this antigen was not present in BE-PCV-14. This indicates that serotype 6B of BE-PCV-14 cross protects serotype 6A. BE-PCV-14 also elicited comparable serotype specific functional OPA immune responses to all the serotypes common to PCV-13.

INTERPRETATIONS

BE-PCV-14 was found to be safe and induced robust and functional serotype specific immune responses to all 14 serotypes. It also elicited cross protective immune response against serotype 6B.These findings suggest that BE-PCV-14 can be safely administered to infants and achieve protection against pneumococcal disease caused by serotypes covered in the vaccine. The study was prospectively registered with clinical trial registry of India - CTRI/2020/02/023129.

Pneumococcal serotypes and risk factors in adult community-acquired pneumonia 2018-20; a multicentre UK cohort study

Background

Higher-valency pneumococcal vaccines are anticipated. We aimed to describe serotype distribution and risk factors for vaccine-serotype community-acquired pneumonia (CAP) in the two years pre-SARS-CoV-2 pandemic.

Methods

We conducted a prospective cohort study of adults hospitalised with CAP at three UK sites between 2018 and 2020. Pneumococcal serotypes were identified using a 24-valent urinary-antigen assay and blood cultures. Risk factors associated with vaccine-type pneumonia caused by serotypes in the 13-, 15- and 20-valent pneumococcal conjugate vaccines (PCV13, PCV15, PCV20) and 23-valent pneumococcal polysaccharide vaccine (PPV23) were determined from multivariable analysis.

Findings

Of 1921 adults hospitalised with CAP, 781 (40.7%, 95% confidence intervals (CI) 38.5-42.9%) had pneumococcal pneumonia. A single PCV13-serotype was detected in 242 (31.0%, 95% CI 27.8-34.3%) pneumococcal CAP patients, mostly serotype 3 (171/242, 70.7%, 95% CI 64.5-76.0%). The additional two PCV15-serotypes were detected in 31 patients (4%, 95% CI 2.8-5.6%), and PCV20-non13-serotypes in 192 (24.6%), with serotype 8 most prevalent (123/192, 64.1%, 95% CI 57.1-70.5%). Compared to PCV13-serotype CAP, people with PCV20-non13 CAP were younger (median age 62 versus 72 years, p < 0.001) and less likely to be male (44% versus 61%, p = 0.01). PPV23-non13-serotypes were found in 252 (32.3%, 95% CI 29.1-35.6%) pneumococcal CAP patients.

Interpretation

Despite mature infant pneumococcal programmes, the burden of PCV13-serotype pneumonia remains high in older adults, mainly due to serotype 3. PCV20-non13-serotype pneumonia is more likely in younger people with fewer pneumococcal risk factors.

Funding

Unrestricted investigator-initiated research grant from Pfizer, United Kingdom; support from National Institute for Health Research (NIHR) Biomedical Research Centre, Nottingham.

Phase 3 trial to evaluate the safety, tolerability, and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine, followed by 23-valent pneumococcal polysaccharide vaccine 6 months later, in at-risk adults 18-49 years of age (PNEU-DAY): A subgroup analysis by baseline risk factors

Immunocompetent adults with certain medical and behavioral factors are at increased risk of pneumococcal disease. In some countries, sequential vaccination with 13-valent pneumococcal conjugate vaccine (PCV13) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for at-risk adults. This subgroup analysis from a phase 3 study evaluated the safety, tolerability, and immunogenicity of sequential administration of either V114 (a 15-valent PCV containing serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F, and 33F) or PCV13, followed 6 months later by PPSV23, in immunocompetent adults 18-49 years of age with pre-defined risk factors for pneumococcal disease. Safety and immunogenicity post-vaccination were analyzed by type and baseline number of risk factors for pneumococcal disease (1 and ≥2 risk factors). This analysis included 1,131 participants randomized 3:1 to receive either V114 or PCV13, followed by PPSV23. The majority (73.1%) of participants had at least one risk factor. Safety and tolerability profiles of V114 and PCV13 were similar across risk factor groups. V114 administered either alone or sequentially with PPSV23 6 months later was immunogenic for all 15 serotypes, including those not contained in PCV13, regardless of the number of baseline risk factors. V114 has the potential to broaden serotype coverage for at-risk adults.

Oral Self-Care, Pneumococcal Vaccination, and Pneumonia Among Japanese Older People, Assessed With Machine Learning

BACKGROUND

Pneumonia is a leading cause of death worldwide. It is a particularly serious burden in older people, as they tend to have a weakened immune response. Identifying the role of oral self-care and pneumococcal vaccination in healthy, independent older people can aid pneumonia prevention among them. This study investigated the associations between oral self-care, pneumococcal vaccination, and pneumonia experience among independent older people.

METHODS

This cross-sectional study used data from the 2016 Japan Gerontological Evaluation Study. We used machine learning to examine the association between oral self-care and the experience of pneumonia over the previous year, stratified by pneumococcal vaccination. The covariates were sex, age, years of education, equivalent annual income, medical history of stroke, oral health status (choking, dryness, number of teeth), and smoking status. The analysis included 17 217 independent older people aged 65 and over.

RESULTS

The prevalence of pneumonia experienced among those who brushed their teeth once or less per day was 4.5% and 5.3% for those with and those without pneumococcal vaccinations, respectively. In the unvaccinated group, the odds ratio of pneumonia experience for those who brushed their teeth once or less a day was 1.57 (95% confidence interval: 1.15-2.14) compared to those who brushed their teeth 3 or more times a day. By contrast, there was no significant association between the frequency of toothbrushing and the experience of pneumonia among people who received pneumococcal vaccination.

CONCLUSIONS

Oral care influenced the experience of pneumonia among independent older people who did not receive pneumococcal vaccination.

Characterization of pneumococcal serotype 7F in vaccine conjugation

Streptococcus pneumoniae is a highly invasive bacterial pathogen that can cause a range of illnesses. Pneumococcal capsular polysaccharides (CPS) are the main virulence factors that causes invasive pneumococcal disease (IPD). Pneumococcal CPS serotype 7F along with a few other serotypes is more invasive and likely to cause IPD. Therefore, 7F is a target for pneumococcal vaccine development, and is included in the two recently approved multi-valent pneumococcal conjugated vaccines, i.e. VAXNEUVANCE and PREVNAR 20.To support process and development of our 15-valent pneumococcal conjugated vaccine (PCV15), chromatographic methods have been developed for 7F polysaccharide and conjugate characterization. A size-exclusion chromatography (SEC) method with UV, light scattering and refractive index detections was employed for concentration, size and conformation analysis. A reversed-phase ultra-performance liquid chromatography (RP-UPLC) method was used for analysis of conjugate monosaccharide composition and degree of conjugation. The collective information obtained by these chromatographic analysis provided insights into the pneumococcal conjugate and conjugation process.

Emerging vaccine strategies against the incessant pneumococcal disease

The incidence of invasive pneumococcal disease (IPD) caused by infection with the pathogen Streptococcus pneumoniae (Spn) has been on a downward trend for decades due to worldwide vaccination programs. Despite the clinical successes observed, the Center for Disease Control (CDC) reports that the continued global burden of S. pneumoniae will be in the millions each year, with a case-fatality rate hovering around 5%. Thus, it is a top priority to continue developing new Spn vaccination strategies to harness immunological insight and increase the magnitude of protection provided. As emphasized by the World Health Organization (WHO), it is also crucial to broaden the implementation of vaccines that are already obtainable in the clinical setting. This review focuses on the immune mechanisms triggered by existing pneumococcal vaccines and provides an overview of the current and upcoming clinical strategies being employed. We highlight the associated challenges of serotype selectivity and using pneumococcal-derived proteins as alternative vaccine antigens.

Clinical and economic burden of pneumococcal disease among adults in Sweden: A population-based register study

Pneumococcal disease is a major cause of clinical and economic burden worldwide. This study investigated the burden of pneumococcal disease in Swedish adults. A retrospective population-based study was conducted using Swedish national registers, including all adults aged ≥18 years with a diagnosis of pneumococcal disease (defined as pneumococcal pneumonia, meningitis, or septicemia) in inpatient or outpatient specialist care between 2015-2019. Incidence and 30-day case fatality rates, healthcare resource utilization, and costs were estimated. Results were stratified by age (18-64, 65-74, and ≥75 years) and the presence of medical risk factors. A total of 10,391 infections among 9,619 adults were identified. Medical factors associated with higher risk for pneumococcal disease were present in 53% of patients. These factors were associated with increased pneumococcal disease incidence in the youngest cohort. In the cohort aged 65-74 years, having a very high risk for pneumococcal disease was not associated with an increased incidence. Pneumococcal disease incidence was estimated at 12.3 (18-64), 52.1 (64-74), and 85.3 (≥75) per 100,000 population. The 30-day case fatality rate increased with age (18-64: 2.2%, 65-74: 5.4%, ≥75: 11.7%), and was highest among septicemia patients aged ≥75 (21.4%). The 30-day average number of hospitalizations was 1.13 (18-64), 1.24 (64-74) and 1.31 (≥75). The average 30-day cost/infection was estimated at €4,467 (18-64), €5,278 (65-74), and €5,898 (≥75). The 30-day total direct cost of pneumococcal disease between 2015-2019 was €54.2 million, with 95% of costs from hospitalizations. The clinical and economic burden of pneumococcal disease in adults was found to increase with age, with nearly all costs associated with pneumococcal disease from hospitalizations. The 30-day case fatality rate was highest in the oldest age group, though not negligible in the younger age groups. The findings of this study can inform the prioritization of pneumococcal disease prevention in adult and elderly populations.

Invasive pneumococcal disease among the elderly in the later era of paediatric pneumococcal conjugate vaccination-A longitudinal study over 10 years based on public surveillance data in the Nordics

BACKGROUND

Pneumococcal conjugate vaccines (PCVs) have proven effective in preventing both non-invasive and invasive pneumococcal disease (IPD) in small children and in older age groups. However, long-term observations and country comparisons of IPD incidence in the elderly following introduction of PCVs in paediatric national immunisation programmes (NIPs) are scarce. We aimed to estimate and compare incidence of IPD in the elderly in Denmark, Finland, Norway, and Sweden over a 10-year time span. During the study period Denmark and Norway used PCV13 in their paediatric NIP, Sweden both PCV10 and PCV13 and Finland used PCV10. Uptake of pneumococcal vaccines for the elderly was low.

METHOD

We collected longitudinal data on confirmed IPD cases and their serotypes among elderly people (aged ≥65 years) 2010-2019 in the four countries of interest. Annual IPD incidence rates were calculated per country, by vaccine-associated serotypes (PCV10, PCV13, PCV15, PCV20 and PPV23) and for non-vaccine serotypes. A regression model was used to estimate average annual change in incidence in each country.

RESULTS

Incidence rates of IPD in the elderly in 2019 ranged from 31.4 to 41.8 per 100,000 people across the countries. Denmark and Norway showed an annual average decline in IPD incidence (-3.3; 95% CI: -5.6 to -1.1; p<0.01) and (-3.3; 95% CI: -5.5 to -1.0; p<0.01) respectively from 2010 to 2019, whereas no change was seen for Sweden (-0.5; 95% CI: -1.9 to 0.8; p = 0.39) or Finland (0.9; 95% CI: -1.0 to 2.7; p = 0.32). IPD incidence due to emerging serotypes, e.g., serotypes 8 and 12F, has increased. Serotype 19A remained a major cause of IPD in countries with PCV10 in paediatric NIPs.

CONCLUSION

Despite paediatric PCV programmes, a considerable vaccine preventable IPD burden remains in the elderly. Further, choice of PCV in paediatric programs was associated with differences in serotype distribution and incidence amongst the elderly. Direct vaccination of the elderly with recently approved broad coverage PCVs holds promise for meaningful impact on disease burden with PCV20 covering a majority of IPD amongst the elderly in the four studied countries. Effectiveness of new vaccines in real-life clinical practice should be followed.

The Two Faces of Bacterial Membrane Vesicles: Pathophysiological Roles and Therapeutic Opportunities

Bacterial membrane vesicles (MVs) are nanosized lipid particles secreted by lysis or blebbing mechanisms from Gram-negative and -positive bacteria. It is becoming increasingly evident that MVs can promote antimicrobial resistance but also provide versatile opportunities for therapeutic exploitation. As non-living facsimiles of parent bacteria, MVs can carry multiple bioactive molecules such as proteins, lipids, nucleic acids, and metabolites, which enable them to participate in intra- and interspecific communication. Although energetically costly, the release of MVs seems beneficial for bacterial fitness, especially for pathogens. In this review, we briefly discuss the current understanding of diverse MV biogenesis routes affecting MV cargo. We comprehensively highlight the physiological functions of MVs derived from human pathogens covering in vivo adaptation, colonization fitness, and effector delivery. Emphasis is given to recent findings suggesting a vicious cycle of MV biogenesis, pathophysiological function, and antibiotic therapy. We also summarize potential therapeutical applications, such as immunotherapy, vaccination, targeted delivery, and antimicrobial potency, including their experimental validation. This comparative overview identifies common and unique strategies for MV modification used along diverse applications. Thus, the review summarizes timely aspects of MV biology in a so far unprecedented combination ranging from beneficial function for bacterial pathogen survival to future medical applications.

Incidence and risk factors of pneumococcal pneumonia in adults: a population-based study

BACKGROUND

Infection caused by Streptococcus pneumoniae, mainly invasive pneumococcal disease (IPD) and pneumococcal pneumonia (PP), are a major public health problem worldwide. This study investigated population-based incidence and risk of PP among Catalonian persons ≥ 50 years-old with and without specific underlying conditions/comorbidities, examining the influence of single and multi-comorbidities in the risk of suffering PP.

METHODS

Population-based cohort study involving 2,059,645 persons ≥ 50 years-old in Catalonia, Spain, who were retrospectively followed between 01/01/2017-31/12/2018. The Catalonian information system for development of research in primary care (SIDIAP) was used to establish baseline characteristics of the cohort (comorbidities/underlying conditions), and PP cases were collected from discharge codes (ICD-10: J13) of the 68 referral Catalonian hospitals.

RESULTS

Global incidence rate (IR) was 90.7 PP cases per 100,000 person-years, with a 7.6% (272/3592) case-fatality rate (CFR). Maximum IRs emerged among persons with history of previous IPD or all-cause pneumonia, followed by haematological neoplasia (475.0), HIV-infection (423.7), renal disease (384.9), chronic respiratory disease (314.7), liver disease (232.5), heart disease (221.4), alcoholism (204.8), solid cancer (186.2) and diabetes (159.6). IRs were 42.1, 89.9, 201.1, 350.9, 594.3 and 761.2 in persons with 0, 1, 2, 3, 4 and ≥ 5 comorbidities, respectively. In multivariable analyses, HIV-infection (hazard ratio [HR]: 5.16; 95% CI: 3.57-7.46), prior all-cause pneumonia (HR: 3.96; 95% CI: 3.45-4.55), haematological neoplasia (HR: 2.71; 95% CI: 2.06-3.57), chronic respiratory disease (HR: 2.66; 95% CI: 2.47-2.86) and prior IPD (HR: 2.56; 95% CI: 2.03-3.24) were major predictors for PP.

CONCLUSION

Apart of increasing age and immunocompromising conditions (classically recognised as high-risk conditions), history of prior IPD/pneumonia, presence of chronic pulmonary/respiratory disease and/or co-existing multi-comorbidity (i.e., two or more underlying conditions) are major risk factors for PP in adults, with an excess risk near to immunocompromised subjects. Redefining risk categories for PP, including all the above-mentioned conditions into the high-risk category, could be necessary to improve prevention strategies in middle-aged and older adults.

Safety, tolerability, and immunogenicity of a 21-valent pneumococcal conjugate vaccine, V116, in healthy adults: phase 1/2, randomised, double-blind, active comparator-controlled, multicentre, US-based trial

BACKGROUND

A pneumococcal conjugate vaccine (PCV) specifically focused on serotypes associated with adult residual disease burden is urgently needed. We aimed to assess V116, an investigational 21-valent PCV, that contains pneumococcal polysaccharides (PnPs), which account for 74-94% of invasive pneumococcal disease in adults aged 65 years or older.

METHODS

We did a phase 1/2, randomised, double-blind, active comparator-controlled, multicentre, non-inferiority and superiority trial. The phase 1 study was done at two clinical sites in the USA, and the phase 2 study was done in 18 clinical sites in the USA. Eligible participants were healthy adults with or without chronic medical conditions assessed as stable, aged 18-49 years in the phase 1 trial and aged 50 years or older in the phase 2 trial. Participants were excluded if they had a history of invasive pneumococcal disease or other culture-positive pneumococcal disease within the past 3 years, known hypersensitivity to a vaccine component, known or suspected impairment of immunological function, were pregnant or were breastfeeding, or had previously received any pneumococcal vaccine. Participants had to abstain from sexual activity or use protocol approved contraception. All participants were centrally randomly assigned to a vaccine group using an interactive response technology system. Participants and investigators were masked to group assignment. In phase 1, participants were randomly assigned (1:1:1) to receive a single dose of V116-1 (2 μg per pneumococcal polysaccharide [PnP] per 0·5 mL) or V116-2 (4 μg per PnP per 1·0 mL) or the 23-valent unconjugated PnP vaccine, PPSV23 (25 μg per PnP per 0·5 mL). In phase 2, participants were randomly assigned (1:1) to receive one dose of V116 (4 μg per PnP per 1·0 mL) or PPSV23 (25 μg per PnP per 0·5 mL), stratified by age. Safety analyses included all randomly assigned participants who received study vaccine; immunogenicity analyses were per protocol. For both phases, the primary safety outcome was the proportion of participants with solicited injection-site adverse events and solicited systemic adverse events up to day 5 after vaccination and the proportion of participants with vaccine-related serious adverse events to 6 months after vaccination. In phase 2, primary immunogenicity outcomes were to test non-inferiority of V116 compared with PPSV23 as measured by serotype-specific opsonophagocytic antibody geometric mean titres (OPA-GMT) ratios for the serotypes common to the two vaccines at 30 days after vaccination (using a 0·33 margin) and to test superiority of V116 compared with PPSV23 as measured by serotype-specific OPA-GMT ratios for the serotypes unique to V116 at 30 days after vaccination (using a 1·0 margin). This trial is registered with Clinicaltrials.gov, NCT04168190.

FINDINGS

Between Dec 6 and 26, 2019, 92 volunteers were screened and 90 (98%) enrolled for phase 1 (59 [66%] women; 31 [34%] men); 30 participants were assigned to each group and received study vaccine. 30 (100%) participants in the V116-1 group, 29 (97%) in the V116-2 group, and 30 (100%) participants in the PPSV23 group were included in the per-protocol immunogenicity evaluation. From Sept 23, 2020, to Jan 12, 2021, 527 volunteers were screened, and 510 (97%) participants were enrolled in the phase 2 trial. 508 participants (>99%; 254 [100%] of 254 participants randomly assigned to the V116 group and 254 [99%] of 256 randomly assigned to PPSV23 group) received study vaccine (281 [55%] women; 227 [45%] men). 252 (99%) of 254 of participants in the V116 group and 254 (99%) of 256 participants in the PPSV23 group were included in the primary immunogenicity analyses. There were no vaccine-related serious adverse events or vaccine-related deaths in either study phase. In both phases, the most common solicited injection site adverse event was injection site pain (phase 1 22 [73%] participants in V116-1 group, 23 [77%] participants in V116-2 group, and 17 [57%] participants in the PPSV23 group; phase 2 118 [46%] of 254 participants in the V116 group and 96 [38%] of 254 in the PPSV23 group]. The most common solicited systemic adverse events in phase 1 was fatigue (eight [27%] participants in the V116-1 group, eight [27%] participants in the V116-2 group, and five [17%] participants in PPSV23 group) and myalgia (eight [27%] participants in the V116-1 group, nine (30%) participants in the V116-2 group, and four (13%) participants in the PPSV23 group]. In phase 2, the most frequently reported solicited systemic adverse event was fatigue (49 [19%] participants in V116 group, and 31 [12%] participants in PPSV23 group). In both phases, most of the solicited adverse events in all vaccine groups were mild and of short duration (≤3 days). V116 met non-inferiority criteria compared with PPSV23 for the 12 shared serotypes and met superiority criteria compared to PPSV23 for the nine unique serotypes.

INTERPRETATION

V116 was well tolerated with a safety profile generally similar to PPSV23; consistent with licensed pneumococcal conjugate vaccines. Functional OPA antibodies were induced to all V116 vaccine serotypes. The vaccine was non-inferior to PPSV23 for the 12 serotypes common to both vaccines and superior to PPSV23 for the nine unique serotypes in V116. Our findings support the development of V116 for prevention of pneumococcal disease in adults.

FUNDING

Merck Sharp & Dohme, subsidiary of Merck & Co, Rahway, NJ, USA.

Antibody enhanced HPLC for serotype-specific quantitation of polysaccharides in pneumococcal conjugate vaccine

Bacterial infection remains as one of the major healthcare issues, despite significant scientific and medical progress in this field. Infection by Streptococcus Pneumoniae (S. Pneumoniae) can cause pneumonia and other serious infectious diseases, such as bacteremia, sinusitis and meningitis. The pneumococcal capsular polysaccharides (CPS) that constitute the outermost layer of the bacterial cell are the main immunogens and protect the pathogen from host defense mechanisms. Over 90 pneumococcal CPS serotypes have been identified, among which more than 30 can cause invasive pneumococcal diseases that could lead to morbidity and mortality. Multivalent pneumococcal vaccines have been developed to prevent diseases caused by S. Pneumoniae. These vaccines employ either purified pneumococcal CPSs or protein conjugates of these CPSs to generate antigen-specific immune responses for patient protection. Serotype-specific quantitation of these polysaccharides (Ps) antigen species are required for vaccine clinical dosage, product release and quality control. Herein, we have developed an antibody-enhanced high-performance liquid chromatography (HPLC) assay for serotype-specific quantitation of the polysaccharide contents in multivalent pneumococcal conjugate vaccines (PCVs). A fluorescence-labeled multiplex assay format has also been developed. This work laid the foundation for a serotype-specific antigen assay format that could play an important role for future vaccine research and development.

Evaluating clinical effectiveness and impact of anti-pneumococcal vaccination in adults after universal childhood PCV13 implementation in Catalonia, 2017-2018

Background

At present, because of indirect effects derived from routine childhood immunisation, clinical benefits vaccinating adults with the 23-valent pneumococcal polysaccharide vaccine (PPsV23) and/or the 13-valent pneumococcal conjugate vaccine (PCV13) are uncertain. This study investigated clinical effectiveness for both PPsV23/PCV13 in preventing pneumonia among Catalonian adults during an earlier 2-year period post-PCV13 free (publicly funded) approval for infants.

Methods

We conducted a Population-based cohort study involving 2,059,645 adults ≥ 50 years in Catalonia, Spain, who were followed between 01/01/2017-31/12/2018. Primary outcomes were hospitalisation from pneumococcal pneumonia (PP) or all-cause pneumonia (ACP) and main explanatory variable was PCV13/PPsV23 vaccination status. Cox regression models were used to estimate vaccination effectiveness adjusted by age/sex and underlying-risk conditions.

Results

Cohort members were followed for 3,958,528 person-years (32,328 PCV13-vaccinated, 1,532,186 PPsV23-vaccinated), observing 3592 PP (131 in PCV13-vaccinated vs 2476 in PPsV23-vaccinated) and 24,136 ACP (876 in PCV13-vaccinated vs 17,550 in PPsV23-vaccinated). Incidence rates (per 100,000 person-years) were 90.7 for PP (394.2 in PCV13-vaccinated vs 161.6 in PPsV23-vaccinated) and 609.7 for ACP (2636.3 in PCV13-vaccinated vs 1145.4 in PPsV23-vaccinated). The PCV13 was associated with an increased risk of PP (hazard ratio [HR]: 1.24; 95% CI: 1.00-1.52; p = 0.046) and ACP (HR: 1.38; 95% CI: 1.28-1.49; p < 0.001) whereas the PPsV23 did not alter the risk of PP (HR: 1.07; 95% CI: 0.98-1.18; p = 0.153) and slightly increased the risk of ACP (HR: 1.14; 95% CI: 1.10-1.18; p < 0.001). In supplementary analyses focused on at-risk individuals (i.e., elderly persons, immunocompromissing and other chronic illnesses) protective effects of vaccination did not emerge either.

Conclusions

Data does not support clinical benefits from pneumococcal vaccination (nor PCV13 neither PPsV23) against pneumonia among Catalonian middle-aged and older adults in the current era of universal PCV13 childhood immunisation in our setting. New extended valency PCVs are greatly needed.

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 of pneumococcal vaccines among adults aged 65 years and older in China: A comparative study

We aimed to assess the cost-effectiveness and health benefits of 23-valent pneumococcal polysaccharide vaccine (PPSV23), 13-valent pneumococcal conjunctive vaccine (PCV13), and PCV13-PPSV23 sequential vaccination strategies in preventing pneumonia and other pneumococcal diseases among the senior citizens (≥ 65 years) in China. The cost-effectiveness of pneumococcal vaccines compared to no vaccination was estimated using a decision-tree Markov model from a societal perspective. Parameters including epidemiological data, vaccine efficacy and cost data were obtained from previous studies. Cases and deaths averted, quality-adjusted life years (QALYs) gained, and incremental cost-effectiveness ratios (ICERs) were presented as outcomes. Sensitivity analyses were performed to explore the uncertainty in the model. In the base-case analysis, compared with no pneumococcal vaccination, the ICERs of PPSV23, PCV13 and PCV13-PPSV23 are US$10,776.7/QALY, $9,193.2/QALY, and $15,080.0/QALY, respectively. PCV13 is the most cost-effective strategy and the only cost-effective strategy based on a threshold of the one-time national GDP per capita, whereas PPSV23 vaccine strategy is provided with the lowest cost, and PCV13-PPSV23 demonstrates the greatest impact on pneumococcal disease burden. Sensitivity analyses reveal that the results are greatly influenced by serotype coverage, vaccine efficacy, CAP incidence and vaccine prices. The PCV13 vaccination for Chinese seniors is more cost-effective than PPSV23 vaccination and PCV13-PPSV23 sequential vaccination.

Safety of the 15-valent pneumococcal conjugate vaccine: A phase I clinical trial

To evaluate the safety of the 15-valent pneumococcal conjugate vaccine (PCV15 (by LvZhu & Co. Ltd)) in healthy infants aged 2 months (minimum to 6 weeks) and 3 months old. This phase I clinical trial enrolled 80 subjects in Laishui County, Hebei Province, China. The total population was divided into 4 age groups on average: 20 adults (≥18 years) and 20 children (1-5 years) all received one vaccine dose; 20 infants (3 months) received the vaccine according to a 3-dose schedule at 0, 1, and 2 months. Twenty infants (2 months, minimum of 6 weeks old) received the vaccine according to a 3-dose schedule of 0, 2, and 4 months. The adverse events (AEs) until 30 days after each dose and serious adverse events (SAEs) until 6 months after the whole dose were reported. The solicited and unsolicited AE frequencies and laboratory indices were similar among the treatment groups. No vaccine-related SAEs were reported. Most vaccine-related adverse events consisting of systemic and local reactions were fever and pain. One hypersensitivity manifested as systemic urticaria that occurred on the third day after the second dose in the 2-month group. The 15-valent pneumococcal conjugate vaccine was generally well tolerated in infants.

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.

Effectiveness of the 23-valent pneumococcal polysaccharide vaccine against community-acquired pneumonia in older individuals after the introduction of childhood 13-valent pneumococcal conjugate vaccine: A multicenter hospital-based case-control study in Japan

BACKGROUND

In the era of childhood pneumococcal conjugate vaccine (PCV) immunization, especially 13-valent pneumococcal conjugate vaccine (PCV13) immunization, serotype replacement of Streptococcus pneumoniae and herd immunity in adults have been reported worldwide. Therefore, continuous evaluation of the effectiveness of the pneumococcal vaccine in adults is crucial because vaccine effectiveness may change owing to these factors. The purpose of this study was to evaluate the effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) against all-cause pneumonia and pneumococcal pneumonia in older individuals with community-acquired pneumonia (CAP) after the introduction of childhood PCV13 in Japan, a topic that has remained largely unexplored.

METHODS

We evaluated pneumococcal vaccine effectiveness in this multicenter, matched case-control study conducted in hospitals and clinics. Cases included patients (aged ≥ 65 years) newly diagnosed with CAP between October 2016 and September 2019. A maximum of five non-pneumonia control patients matched for sex, school grade, date of outpatient visit, and medical institution were selected for each case. Conditional logistic regression models were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) of pneumococcal vaccines for the occurrence of all-cause CAP and pneumococcal CAP.

RESULTS

The analysis included 740 individuals (142 patients and 598 controls). The median age of participants was 75 years (men: 54%). The adjusted OR for pneumococcal vaccination against all-cause CAP was 1.31 (95% CI: 0.84-2.06), while that for PPSV23 vaccination in the previous 5 years was 1.33 (95% CI: 0.85-2.09). The adjusted OR for PPSV23 vaccination in the previous 5 years against pneumococcal CAP was 0.93 (95% CI: 0.35-2.50).

CONCLUSIONS

This study was unable to demonstrate the effectiveness of PPSV23 against all-cause and pneumococcal pneumonia after the introduction of childhood PCV13 in Japan. Nonetheless, additional studies are needed to validate these results.

Effectiveness of the 23-valent pneumococcal polysaccharide vaccine against invasive pneumococcal disease among 948,263 individuals ≥ 65 years of age: a Danish cohort study

This study aimed to estimate the effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPV23) against invasive pneumococcal disease (IPD) among individuals ≥ 65 years of age. We used Danish nationwide databases to obtain information on PPV23 vaccination, covariates, and IPD and linked data on an individual level using a unique personal identifier. A total of 948,263 individuals were included and followed between June 15, 2020, and September 18, 2021 (58.6% were vaccinated during follow-up). The adjusted vaccine effectiveness was 42% (95% confidence interval (CI): 9–63%) for all-serotype IPD and 58% (95% CI: 21–78%) for PPV23-serotype IPD, using no vaccination as the reference.

Pneumococcal pericarditis in a patient with newly diagnosed diabetes mellitus: a case report

Background

After the introduction of antibiotics, pneumococcal pericarditis has become a rare finding. However, this severe condition with high mortality and complication rates requires rapid recognition and intervention. Herein, we describe a patient that presents with this rare disease resulting in an unusual, fatal outcome.

Case presentation

A previously healthy, 68-year-old, Caucasian male presented with progressive fatigue, dyspnea, and appetite loss since 12 days. He was diagnosed with diabetes mellitus 5 days before presentation but had not started treatment. After echocardiography revealed pericardial effusion, pericardiocentesis was performed with immediate drainage of a large volume of purulent fluid suggestive of bacterial pericarditis. On the basis of cultures showing Streptococcus pneumoniae as the causative organism, a regimen of intravenous penicillin was initiated. Additionally, antidiabetic drugs were started as his diabetes also predisposed him to invasive infectious disease. No other primary source of the infection, such as pneumonia, was found. Though the patient was found to be severely ill on admission, his clinical condition improved. A total of 1235 mL of pericardial fluid was drained, and adequate drainage was confirmed by daily, bedside echocardiography. However, 6 days post-admission, the patient suddenly developed intrapericardial bleeding with blood clot formation on the right chamber with subsequent cardiac tamponade. With the blood clot precluding adequate drainage through the catheter, the patient suffered cardiac arrest and died before surgical intervention could be attempted.

Conclusions

Pneumococcal pericarditis is a very rare but life-threatening disease that necessitates immediate intervention with antibiotics and drainage of the pericardial effusion. Thus, although symptoms may be variable and aspecific, early recognition of this condition is critical. The present case illustrates the presentation, diagnosis, and clinical course of a patient presenting with pneumococcal pericarditis in current clinical practice. Through this report, we aimed to increase awareness among clinicians both of the existence of this phenomenon and of its uncertain clinical course. As is highlighted by the case, patients with pneumococcal pericarditis are at high risk for complications and should be closely monitored.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13256-022-03548-8.

Characterization of High Molecular Weight Pneumococcal Conjugate by SEC-MALS and AF4-MALS

Infections by Streptococcus pneumoniae can cause serious pneumococcal diseases and other medical complications among patients. Polysaccharide-based vaccines have been successfully developed as prophylactic agents against such deadly bacterial infections. In the 1980s, PNEUMOVAX^® 23 were introduced as the first pneumococcal polysaccharide vaccines (PPSV). Later, pneumococcal polysaccharides were conjugated to a carrier protein to improve immune responses. Pneumococcal conjugate vaccines (PCV) such as PREVNAR^® and VAXNEUVANCE™ have been developed. Of the more than 90 pneumococcal bacteria serotypes, serotype 1 (ST-1) and serotype 4 (ST-4) are the two main types that cause invasive pneumococcal diseases (IPD) that could lead to morbidity and mortality. Development of a novel multi-valent PCV against these serotypes requires extensive biophysical and biochemical characterizations of each monovalent conjugate (MVC) in the vaccine. To understand and characterize these high molecular weight (Mw) polysaccharide protein conjugates, we employed the multi-angle light scattering (MALS) technique coupled with size-exclusion chromatography (SEC) separation and asymmetrical flow field flow fractionation (AF4). MALS analysis of MVCs from the two orthogonal separation mechanisms helps shed light on the heterogeneity in conformation and aggregation states of each conjugate.

A Multicenter Evaluation of Trends in Antimicrobial Resistance among Streptococcus pneumoniae Isolates from Adults in the United States

Background

Management of pneumococcal disease is complicated by high rates of antimicrobial resistance (AMR). This study assessed AMR trends for Streptococcus pneumoniae isolates from adults with pneumococcal disease.

Methods

From January 2011 to February 2020, we evaluated 30-day nonduplicate S. pneumoniae isolates from 290 US hospitals (BD Insights Research Database) from adults (≥18 years) in inpatient and outpatient settings. Isolates were required to have ≥1 AMR result for invasive (blood, cerebrospinal fluid/neurologic) or noninvasive (respiratory or ear/nose/throat) pneumococcal disease samples. Determination of AMR was based on facility reports of intermediate or resistant. Descriptive statistics and generalized estimated equations were used to assess variations over time.

Results

Over the study period, 34 039 S. pneumoniae isolates were analyzed (20 749 [61%] from noninvasive sources and 13 290 [39%] from invasive sources). Almost half (46.6%) of the isolates were resistant to ≥1 drug, and noninvasive isolates had higher rates of AMR than invasive isolates. Total S. pneumoniae isolates had high rates of resistance to macrolides (37.7%), penicillin (22.1%), and tetracyclines (16.1%). Multivariate modeling identified a significant increasing trend in resistance to macrolides (+1.8%/year; P < .001). Significant decreasing trends were observed for penicillin (−1.6%/year; P < .001), extended-spectrum cephalosporins (ESCs; −0.35%/year; P < .001), and ≥3 drugs (−0.5%/year; P < .001).

Conclusions

Despite decreasing trends for penicillin, ESCs, and resistance to ≥3 drugs, AMR rates are persistently high in S. pneumoniae isolates among US adults. Increasing macrolide resistance suggests that efforts to address AMR in S. pneumoniae may require antimicrobial stewardship efforts and higher-valent pneumococcal conjugate vaccines.

Sex and gender differences in community-acquired pneumonia

Awareness of the influence of sex ands gender on the natural history of several diseases is increasing. Community-acquired pneumonia (CAP) is the most common acute respiratory disease, and it is associated with both morbidity and mortality across all age groups. Although a role for sex- and gender-based differences in the development and associated complications of CAP has been postulated, there is currently high uncertainty on the actual contribution of these factors in the epidemiology and clinical course of CAP. More evidence has been produced on the topic during the last decades, and sex- and gender-based differences have also been extensively studied in COVID-19 patients since the beginning of the SARS-CoV-2 pandemic. This review aims to provide an extensive outlook of the role of sex and gender in the epidemiology, pathogenesis, treatment, and outcomes of patients with CAP, and on the future research scenarios, with also a specific focus on COVID-19.

Immunogenicity, Safety, and Tolerability of V114, a 15-Valent Pneumococcal Conjugate Vaccine, in Immunocompetent Adults Aged 18–49 Years With or Without Risk Factors for Pneumococcal Disease: A Randomized Phase 3 Trial (PNEU-DAY)

Background

Adults with certain medical and behavioral factors are at increased risk for pneumococcal disease (PD). Sequential vaccination with 13-valent pneumococcal conjugate vaccine (PCV13) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) is recommended for at-risk adults in some countries.

Methods

This phase 3 trial evaluated the safety, tolerability, and immunogenicity of sequential administration of either V114 (a 15-valent PCV containing serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F, and 33F) or PCV13, followed 6 months later by PPSV23, in immunocompetent adults aged 18–49 years with or without pre-defined risk factors for PD (NCT03547167). Overall, 1515 participants were randomized 3:1 to receive either V114 or PCV13, followed by PPSV23.

Results

Most common solicited adverse events (AEs) following administration of V114 or PCV13 as well as PPSV23 were injection-site pain and fatigue. The proportion of participants with AEs was comparable in both groups. V114 and PCV13 were immunogenic based on opsonophagocytic activity (OPA) geometric mean titers (GMTs) 30 days post-vaccination for all serotypes contained in each respective vaccine. OPA GMTs to the 2 unique serotypes in V114 were robust in the V114 group. PPSV23 was immunogenic for all 15 serotypes contained in V114 in both vaccination groups, including 22F and 33F.

Conclusions

V114 administered alone or sequentially with PPSV23 is well tolerated and immunogenic for all 15 serotypes, including those not contained in PCV13, in immunocompetent adults aged 18–49 years with or without certain medical or behavioral risk factors for PD.

A phase 3 trial of safety, tolerability, and immunogenicity of V114, 15-valent pneumococcal conjugate vaccine, compared with 13-valent pneumococcal conjugate vaccine in adults 50 years of age and older (PNEU-AGE)

BACKGROUND

Pneumococcal conjugate vaccines (PCVs) have greatly reduced the incidence of pneumococcal disease, yet unmet medical need remains due to increased disease caused by non-vaccine serotypes (STs). V114 (VAXNEUVANCE^TM, Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA) is a 15-valent PCV containing 13 serotypes in licensed PCV13 and 2 additional serotypes (22F, 33F) which significantly contribute to pneumococcal disease burden. This phase 3 trial compared safety, tolerability, and immunogenicity of V114 to PCV13 in adults ≥50 years of age.

METHODS

Adults were randomized 1:1 to receive a single dose of V114 or PCV13; randomization was stratified by age (50-64 years, 65-74 years, and ≥75 years). Adverse events (AEs) were collected following vaccination. Serotype-specific opsonophagocytic activity (OPA) and immunoglobulin G (IgG) antibodies were measured prior to and 30 days after vaccination (Day 30). Primary objectives included assessing noninferiority of V114 to PCV13 for the 13 shared serotypes and superiority of V114 to PCV13 for the two unique serotypes. Superiority of V114 to PCV13 for shared serotype 3 was assessed as a secondary objective.

RESULTS

Overall, 1,202 participants were vaccinated (V114 N = 602, PCV13 N = 600). The most commonly reported AEs across both groups were injection-site pain, fatigue, and myalgia. V114 met noninferiority criteria compared to PCV13 for the 13 shared serotypes (using a 2-fold non-inferiority margin for the ratio of OPA geometric mean titers [GMTs] [V114/PCV13] at Day 30) and met superiority for the 2 unique serotypes (using a 2-fold super-superiority margin for the ratio of OPA GMTs [V114/PCV13] at Day 30 and a 0.10 super-superiority margin for the difference in proportions of participants with ≥4-fold rise from prevaccination to Day 30). V114 met superiority criteria compared to PCV13 for serotype 3 (based on a super-superiority margin of 1.2 for the ratio of the OPA GMTs [V114/PCV13] and a superiority margin of 0 for the difference in proportions of participants with ≥4-fold rise). [NCT03950622, EudraCT#2018-004316-22, Japic-CTI#194845].

Pneumonia

Pneumonia is a common acute respiratory infection that affects the alveoli and distal airways; it is a major health problem and associated with high morbidity and short-term and long-term mortality in all age groups worldwide. Pneumonia is broadly divided into community-acquired pneumonia or hospital-acquired pneumonia. A large variety of microorganisms can cause pneumonia, including bacteria, respiratory viruses and fungi, and there are great geographical variations in their prevalence. Pneumonia occurs more commonly in susceptible individuals, including children of <5 years of age and older adults with prior chronic conditions. Development of the disease largely depends on the host immune response, with pathogen characteristics having a less prominent role. Individuals with pneumonia often present with respiratory and systemic symptoms, and diagnosis is based on both clinical presentation and radiological findings. It is crucial to identify the causative pathogens, as delayed and inadequate antimicrobial therapy can lead to poor outcomes. New antibiotic and non-antibiotic therapies, in addition to rapid and accurate diagnostic tests that can detect pathogens and antibiotic resistance will improve the management of pneumonia.

Immunogenicity following revaccination or sequential vaccination with 23-valent pneumococcal polysaccharide vaccine (PPSV23) in older adults and those at increased risk of pneumococcal disease: a review of the literature

Introduction: Immunogenicity studies evaluating sequential administration of pneumococcal conjugate vaccine (PCV) followed by 23-valent pneumococcal polysaccharide vaccine (PPSV23) or revaccination with PPSV23 have raised concerns that PPSV23 may not elicit higher antibody levels than those measured following PCV or first PPSV23 dose.Areas covered: Recent literature was evaluated for evidence of blunted immune response (hyporesponsiveness), focusing on studies using adequate intervals between doses in accordance with vaccination recommendations. In eight of nine studies that evaluated revaccination with PPSV23 at an interval of ≥5 years after the previous dose, immunoglobulin G geometric mean concentrations and/or opsonophagocytic assay geometric mean titers for most serotypes increased from pre- to post-repeat vaccination and were comparable between repeat and primary vaccination groups post-vaccination. In seven studies in which PPSV23 was administered after PCVs (8 weeks to 1 year apart), responses to PPSV23 were comparable to those seen after initial PCV dose for shared vaccine serotypes. Studies in which PCVs were administered after PPSV23 were not evaluated.Expert opinion: Published data suggest immune responses following repeat vaccination with PPSV23, or sequential PCV/PPSV23 vaccination, are robust, without evidence of hyporesponsiveness. PPSV23 vaccination of at-risk adults is essential to ensure broad protection against all 23 vaccine serotypes.