Editorial commentary: should 13-valent protein-conjugate pneumococcal vaccine be used routinely in adults?

Potential impact of combined influenza and pneumococcal vaccines on the severity of respiratory illness in COVID-19 infection among type 2 diabetic patients

To retrospectively assess the impact of regular yearly administration of recombinant influenza and single administration of pneumococcal conjugate vaccines on the occurrence of serious respiratory infection including COVID-19 in patients with type 2 diabetes mellitus. Hundred patients with type 2 diabetes mellitus were given Vaxigrip and Prevnar13^® vaccines and were evaluated by comprehensive clinical review, airflow screening questionnaire, and routine laboratory investigations with follow-up during the COVID-19 pandemic and compared to a control group of diabetic patients with the same inclusion criteria (n = 100). After Vaxigrip and Prevnar13, there is a significant improvement in respiratory symptoms and a decrease in the airflow screening questionnaire (p = 0.0001) with a significant improvement in inflammatory parameters as neutrophil-lymphocyte ratio, ESR, CRP, and platelet count. Four patients had mild COVID-19 (4%), mainly gastrointestinal with no complications. Twenty-one out of 32 (65.6%) patients in the control group had severe COVID-19. The hazard ratios of significant respiratory tract infection and death due to COVID-19 were 2.29 and 10.24 in the non-vaccinated control (p = 0.001).The severity of COVID-19 in diabetes correlated with HBA1C (p = 0.007), combined Vaxigrip and Prevnar13 vaccination (p = 0.0001), serum creatinine (p = 0.001), neutrophil-lymphocyte ratio (p = 0.001), and thrombocytopenia (p = 0.003). The present study suggested that the combination of Prevnar13 and Vaxigrip may be related to decreased occurrence of serious respiratory infections including COVID-19. Further randomized control trials may be needed to establish a direct causation between the two and clarify these associations.

Should older adult pneumococcal vaccination recommendations change due to decreased vaccination in children during the pandemic? A cost-effectiveness analysis

BACKGROUND

The COVID-19 pandemic is causing declines in childhood immunization rates. We examined potential COVID-19-related changes in pediatric 13-valent pneumococcal conjugate vaccine (PCV13) use, subsequent impact on childhood and adult pneumococcal disease rates, and how those changes might affect the favorability of PCV13 use in non-immunocompromised adults aged ≥65 years.

METHODS

A Markov model estimated pediatric disease resulting from decreased PCV13 use in children aged <5 years; absolute decreases from 10 to 50% for 1-2 years duration were examined, assuming no catch-up vaccination and that decreased vaccination led to proportionate increases in PCV13 serotype pneumococcal disease in children and seniors. Integrating pediatric model output into a second Markov model examining 65-year-olds, we estimated the cost effectiveness of older adult pneumococcal vaccination strategies while accounting for potential epidemiologic changes from decreased pediatric vaccination.

RESULTS

One year of 10-50% absolute decreases in PCV13 use in <5-year-olds increased pneumococcal disease by an estimated 4-19% in seniors; 2 years of decreased use increased senior rates by 8-38%. In seniors, a >53% increase in pneumococcal disease was required to favor PCV13 use in non-immunocompromised seniors at a $200,000 per quality-adjusted life-year gained threshold, which corresponded to absolute decreases in pediatric PCV13 vaccination of >50% over a 2-year period. In sensitivity analyses, senior PCV13 vaccination was unfavorable if absolute decreases in pediatric PCV13 receipt were within plausible ranges, despite model assumptions favoring PCV13 use in seniors.

CONCLUSION

COVID-19-related decreases in pediatric PCV13 use would need to be both substantial and prolonged to make heightened PCV13 use in non-immunocompromised seniors economically favorable.

Constrained Optimization for Pneumococcal Vaccination in Brazil

OBJECTIVES

To identify the most cost-efficient combination of pneumococcal vaccines in infants and aging adults for a 10-year period in Brazil.

METHODS

Constrained optimization (CO) prioritized 9 pneumococcal vaccine regimens according to their gain in quality-adjusted life-years (QALYs) and their related costs over a prespecified time horizon with defined constraints for 2 age groups, infants and aging adults. The analysis starts from the current universal infant vaccination of pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV), 2 primary and 1 booster dose at 2, 4, and 12 months, respectively. Key constraints are the fixed annual vaccine budget increase and the relative return on investment (ROI_R) per regimen, which must be > 1, the reference intervention being the current vaccination strategy in infants and the most cost-efficient one in aging adults.

RESULTS

The CO analysis including all the constraints indicates that over 10 years the maximum extra health gain is 126 194 QALYs for an extra budget of $974 million Brazilian reals (ROI_R = 1.15). Results could be improved with a higher proportion of the at-risk population in aging adults, less herd effect, and better QALY scores.

CONCLUSION

The study shows that with 4 constraints on budget, time horizon, vaccine coverage, and cost efficiency, a CO analysis could identify the most cost-efficient overall pneumococcal vaccination strategy for Brazil, allowing for limited vaccine budget increase while obtaining appropriate health gain.

Pneumococcal Vaccination in Adults Aged ≥65 Years: Cost-Effectiveness and Health Impact in U.S. Populations

INTRODUCTION

Recommending both the conjugate and polysaccharide pneumococcal vaccines to all U.S. seniors may have little public health impact and be economically unreasonable. Public health impact and cost-effectiveness of using both vaccines in all adults aged ≥65 years were estimated compared with an alternative strategy (omitting pneumococcal conjugate vaccine in the nonimmunocompromised) and with the newly revised recommendation (giving or omitting conjugate vaccine based on patient-physician shared decision making).

METHODS

Strategies were examined in hypothetical U.S. 65-year-old population cohorts and segmented into health states based on age- and population-specific data in a Markov state-transition model with a lifetime time horizon from a healthcare perspective. Black population cohorts were examined separately given greater illness risk and lower vaccine uptake. Model parameters came from the Centers for Disease Control Active Core Bacterial Surveillance network, National Health Interview Survey, and Nationwide Inpatient Sample data. Outcomes included incremental costs per quality-adjusted life year gained and pneumococcal disease outcomes for each strategy. Data were gathered and analysis performed in 2018.

RESULTS

Giving both vaccines, either routinely or with shared decision making, was most effective, reducing pneumococcal disease incidence compared with no vaccination, but costing $765,000-$2.18 million/quality-adjusted life year gained. Depending on examined population and scenario, the alternative strategy cost $65,700-$226,700/quality-adjusted life year gained (less in black populations) and reduced cases and deaths by 0.3%-0.9%.

CONCLUSIONS

A vaccination strategy that omits pneumococcal conjugate vaccine in immunocompetent U.S. seniors may be economically reasonable, particularly for black seniors. Use of both pneumococcal vaccines was more effective but substantially more expensive.

Cost-effectiveness of adult pneumococcal vaccination policies in underserved minorities aged 50-64 years compared to the US general population

BACKGROUND

Changing pneumococcal disease epidemiology due to childhood vaccination has prompted re-examination of US adult pneumococcal vaccination policies, as have considerations of greater pneumococcal disease incidence and higher prevalence of conditions that increase risk in underserved minority populations. Prior analyses suggest routine pneumococcal vaccination at age 50 could be considered, which could disproportionately benefit underserved populations.

METHODS

A Markov cohort model estimated the cost-effectiveness of US pneumococcal vaccination policies in hypothetical 50-year-old underserved minority and general population cohorts. Strategies included receiving one or both available pneumococcal vaccines based on age- or chronic condition-specific criteria. US databases and medical literature data calibrated pneumococcal illness incidence, vaccine serotype distributions, age- and race-specific chronic condition distributions, and costs. Black population data were used as a proxy for underserved minorities. We took a US healthcare perspective, discounting at 3%/year. One-way and probabilistic sensitivity analyses were performed and scenarios modeling differing vaccine assumptions were examined.

RESULTS

In both black and general population 50-year-olds, giving both pneumococcal vaccines to all 50-year-olds prevented the most disease, but cost >$250,000 per quality adjusted life year (QALY) gained. Current CDC recommendations (both vaccines for the immunocompromised, polysaccharide vaccine for other high-risk conditions) were economically favorable in either population when analyses assumed polysaccharide vaccine was ineffective against nonbacteremic pneumococcal pneumonia (NBP). If polysaccharide vaccine is effective against NBP or if less complex age-based vaccination recommendations result in increased vaccine uptake, giving polysaccharide vaccine to all 50-year-olds cost <$100,000/QALY; this effect was more pronounced in black cohorts. Results were robust in 1-way and probabilistic sensitivity analyses.

CONCLUSIONS

Despite changes in pneumococcal epidemiology, current CDC recommendations were favored in underserved minority and general population cohorts. Polysaccharide vaccine for all 50-year-olds could be considered under some vaccine uptake and effectiveness assumptions, particularly if mitigating racial health disparities in pneumococcal disease is a priority.

A Simple Approach to Pneumococcal Vaccination in Adults

Streptococcus pneumoniae is a bacterium responsible for a spectrum of diseases including lobar pneumonia, meningitis, otitis media, and sinusitis. Invasive pneumococcal disease is responsible for significant morbidity and mortality across the world. Concerted efforts led to the development of two vaccinations, Pneumova × 23 and Prevnar 13, for the prevention of pneumococcal disease. The Advisory Committee on Immunization Practices of the US Centers for Disease Control and Prevention provides vaccination schedules for predisposed adults, but the proposed schedules remain a challenge to health-care providers. We performed a systematic review in PubMed and these specialty group websites to present the pathophysiology of pneumococcal disease, outline different pneumococcal vaccinations, and condense recommendations for vaccination administration.

Serotypes of Streptococcus pneumoniae in Egyptian children: are they covered by pneumococcal conjugate vaccines?

In Egypt, pneumococcal vaccines have not yet been introduced as being compulsory. Identification of the circulating serotypes in Egypt is mandatory to determine whether or not the pneumococcal vaccines will be beneficial. The current study aims to identify the serotypes, vaccine coverage, and antimicrobial resistance of Streptococcus pneumoniae colonizing the nasopharynx of Egyptian children younger than 5 years old. The study was conducted in two successive winter seasons (December 2012-February 2013 and December 2013-February 2014). Two hundred children were enrolled, aged from 6 months to 5 years, excluding those with fever, signs of infection, history of antibiotic intake, and hospitalization in the preceding month. Nasopharyngeal (NP) secretions were collected, subjected to culture, and underwent antibiotic susceptibility testing if positive for pneumococci. Real-time polymerase chain reaction (PCR) and serotyping by sequential multiplex PCR for positive cases were included as well. Streptococcus pneumoniae was isolated from 62 subjects. All isolates were sensitive to vancomycin and levofloxacin, but the majority showed resistance to multiple antibiotics. PCR was positive for pneumococci in 113 subjects (56.5%). The most commonly detected serotypes (st) were 6A6B6C (n = 21, 20.8%), 19F (n = 19, 18.8%), 1 (n = 11, 10.9%), 34 (n = 8, 7.9%), and 19A (n = 6, 5.9%). The theoretical coverage of the PCV13 vaccine for the detected serotypes was 72.4%, while that of PCV10 was 65.5%. Based on these percentages, we recommend including pneumococcal conjugate vaccines in the Egyptian national vaccination program.

Should Committees That Write Guidelines and Recommendations Publish Dissenting Opinions?

Medical guidelines tend to convey a sense of unanimity of opinion that may not reflect the deliberations of the experts who wrote them. Using, as an example, an analysis of the recently published recommendations on administering pneumococcal conjugate vaccine to adults, the present article raises the question of whether official recommendations and guidelines should include dissenting opinions, analogous to decisions issued by the US Supreme Court. The argument that such a policy would lead to confusion in our profession is addressed in 2 ways: (1) the current system, in which different professional societies publish conflicting recommendations, as in the case of breast or prostate cancer screening, can be far more confusing, and (2) in the long run, greater transparency will lead to more thoughtful and higher-quality medical care. Perhaps the most important point of this paper is the suggestion that it is far better to bring dissent into the recommendation process than to act as if it is not there.

Surveillance of pneumococcal diseases in Central and Eastern Europe

Pneumococcal infection is a major cause of morbidity and mortality worldwide. The burden of disease associated with S. pneumoniae is largely preventable through routine vaccination. Pneumococcal conjugate vaccines (e.g. PCV7, PCV13) provide protection from invasive pneumococcal disease as well as non-invasive infection (pneumonia, acute otitis media), and decrease vaccine-type nasopharyngeal colonisation, thus reducing transmission to unvaccinated individuals. PCVs have also been shown to reduce the incidence of antibiotic-resistant pneumococcal disease. Surveillance for pneumococcal disease is important to understand local epidemiology, serotype distribution and antibiotic resistance rates. Surveillance systems also help to inform policy development, including vaccine recommendations, and monitor the impact of pneumococcal vaccination. National pneumococcal surveillance systems exist in a number of countries in Central and Eastern Europe (such as Croatia, Czech Republic, Hungary, Poland, Romania and Slovakia), and some have introduced PCVs (Czech Republic, Hungary, Kazakhstan, Russia, Slovakia and Turkey). Those countries without established programs (such as Kazakhstan, Russia and Ukraine) may be able to learn from the experiences of those with national surveillance systems. The serotype distributions and impact of PCV13 on pediatric pneumococcal diseases are relatively similar in different parts of the world, suggesting that approaches to vaccination used elsewhere are also likely to be effective in Central and Eastern Europe. This article briefly reviews the epidemiology of pneumococcal disease, presents the latest surveillance data from Central and Eastern Europe, and discusses any similarities and differences in these data as well the potential implications for vaccination policies in the region.

A review of economic evaluations of 13-valent pneumococcal conjugate vaccine (PCV13) in adults and the elderly

The 13-valent pneumococcal conjugated vaccine (PCV13) is already recommended for some adult groups and is being considered for wider use in many countries. In order to identify the strengths and limitations of the existing economic evaluation studies of PCV13 in adults and the elderly a literature review was conducted. The majority of the studies identified (9 out of 10) found that PCV13 was cost-effective in adults and/or the elderly. However, these results were based on assumptions that could not always be informed by robust evidence. Key uncertainties included the efficacy of PCV13 against non-invasive pneumonia and the herd immunity effect of childhood vaccination programs. Emerging trial evidence on PCV13 in adults from the Netherlands offers the ability to parameterize future economic evaluations with empirical efficacy data. However, it is important that these estimates are used thoughtfully when they are transferred to other settings.

Community-acquired pneumonia: An overview

Community-acquired pneumonia is still a significant cause of morbidity and mortality and is often misdiagnosed and inappropriately treated. Although it can be caused by a wide variety of micro-organisms, the pneumococcus, atypicals, such as Mycoplasma pneumoniae and Chlamydophila pneumoniae,Staphylococcus aureus and certain Gram-negative rods are the usual pathogens encountered. The site-of-care decision is critical in determining the site and type of care as well as the extent of diagnostic workup. Antimicrobial therapy should be started as soon as possible particularly in those requiring admission to hospital, but typically the physician does not know with any degree of certainty the identity of the etiologic pathogen. A number of national guidelines have been published to help the physician with this choice. The initial drug(s) can be modified if necessary if the pathogen and its antimicrobial susceptibility pattern becomes known. Adjunctive therapy such as pressors and fluid replacement are of value and macrolides appear to help as well, likely secondary to their immunomodulatory effects. Recent data also suggest a role for steroids.

Impact of Pneumococcal Conjugate Vaccine Administration in Pediatric Older Age Groups in Low and Middle Income Countries: A Systematic Review

INTRODUCTION

Pneumococcal conjugate vaccine (PCV) is included in the World Health Organization's routine immunization schedule and is recommended by WHO for vaccination in high-risk children up to 60 months. However, many countries do not recommend vaccination in older age groups, nor have donors committed to supporting extended age group vaccination. To better inform decision-making, this systematic review examines the direct impact of extended age group vaccination in children over 12 months in low and middle income countries.

METHODS

An a priori protocol was used. Using pre-specified terms, a search was conducted using PubMed, LILACS, Cochrane Infectious Diseases Group Specialized Register, Cochrane Central Register of Controlled Trials, CAB Abstracts, clinicaltrials.gov and the International Symposium on Pneumococci and Pneumococcal Diseases abstracts. The primary outcome was disease incidence, with antibody titers and nasopharyngeal carriage included as secondary outcomes.

RESULTS

Eighteen studies reported on disease incidence, immune response, and nasopharyngeal carriage. PCV administered after 12 months of age led to significant declines in invasive pneumococcal disease. Immune response to vaccine type serotypes was significantly higher for those vaccinated at older ages than the unimmunized at the established 0.2 ug/ml and 0.35 ug/ml thresholds. Vaccination administered after one year of age significantly reduced VT carriage with odds ratios ranging from 0.213 to 0.69 over four years. A GRADE analysis indicated that the studies were of high quality.

DISCUSSION

PCV administration in children over 12 months leads to significant protection. The direct impact of PCV administration, coupled with the large cohort of children missed in first year vaccination, indicates that countries should initiate or expand PCV immunization for extended age group vaccinations. Donors should support implementation of PCV as part of delayed or interrupted immunization for older children. For countries to effectively implement extended age vaccinations, access to affordably-priced PCV is critical.

Functional immune responses to twelve serotypes after immunization with a 23-valent pneumococcal polysaccharide vaccine in older adults

BACKGROUND

The 23-valent pneumococcal polysaccharide vaccine (PPSV23) was introduced as part of the national immunization program for the elderly (≥65 years of age) in Korea on 2013. To evaluate immune responses in this population, serotype-specific anti-pneumococcal antibodies were studied with opsonophagocytic assay (OPA).

METHODS

Pneumococcal vaccine-naïve participants ≥65 years of age were enrolled. They were divided into two groups according to their age: 30 in (65-74 years) and 32 in group (≥75 years). The functional antibody response was determined by multiplexed OPA (MOPA) for 12 serotypes (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) before and 4 weeks after vaccination with PPSV23.

RESULTS

Geometric mean titers (GMTs) to all tested serotypes significantly increased in both groups after vaccination compared to those before vaccination. There were no significant differences in either the fold rise (post-vaccination to pre-vaccination) or the percentage of participants with a ≥4-fold increase in OPA titers between two groups for any of the 12 serotypes. Following vaccination, GMT for serotype 9V was higher in group 1 than in group 2 (P=0.011).

CONCLUSIONS

PPSV23 induces functional immune response for 12 vaccine serotypes in both age groups. Further analysis is needed for the remaining 11 serotypes in the PPSV23, in order to develop a better understanding of the immune responses induced by PPV23 in older adults.

Randomized controlled study of the safety and immunogenicity of pneumococcal vaccine formulations containing PhtD and detoxified pneumolysin with alum or adjuvant system AS02V in elderly adults

Six vaccine formulations containing AS02V or alum (aluminum phosphate [AlPO4]) adjuvant with pneumococcal proteins, pneumococcal histidine triad D (PhtD), and/or detoxified pneumolysin (dPly), either as a polysaccharide carrier in an 8-valent pneumococcal conjugate vaccine (8PCV) or as free (unconjugated) proteins, were evaluated in adults -65 to 85 years of age. In this phase I observer-blind study, 167 healthy subjects were randomized to receive two doses (days 0 and 60) of 10 or 30 μg PhtD-dPly plus AS02V or alum, 8PCV plus AS02V or alum, or one dose (day 0) of 23-valent polysaccharide pneumococcal vaccine (23PPV) as a control (placebo on day 60). The safety, reactogenicity, and antibody-specific responses to these vaccines were evaluated. No vaccine-related serious adverse events were reported. The incidences of solicited local and specific general (fatigue and myalgia) symptoms tended to be higher in the AS02V groups than in other groups. Anti-PhtD and anti-Ply antibody responses were observed in all groups except the control group. One month post-dose 2, the anti-PhtD and anti-Ply antibody geometric mean concentrations tended to be higher with AS02V than with alum, higher with a dose of 30 μg than with 10 μg for PhtD-dPly and higher with 30-μg PhtD-dPly formulations than with conjugated PhtD and dPly (8PCV) formulations. Functional antibody responses, measured by an opsonophagocytic activity assay, tended to be higher with 8PCV than with 23PPV. In conclusion, vaccine formulations containing free or conjugated PhtD and dPly had acceptable reactogenicity and safety profiles in elderly adults. Immune responses were enhanced with an AS02V-adjuvanted formulation containing free 30-μg PhtD-dPly compared to those with alum adjuvant and conjugated proteins. (This study has been registered at ClinicalTrials.gov under registration no. NCT00756067.).

Impact of preceding flu-like illness on the serotype distribution of pneumococcal pneumonia

BACKGROUND

Even though the pathogenicity and invasiveness of pneumococcus largely depend on capsular types, the impact of serotypes on post-viral pneumococcal pneumonia is unknown.

METHODS AND FINDINGS

This study was performed to evaluate the impact of capsular serotypes on the development of pneumococcal pneumonia after preceding respiratory viral infections. Patients with a diagnosis of pneumococcal pneumonia were identified. Pneumonia patients were divided into two groups (post-viral pneumococcal pneumonia versus primary pneumococcal pneumonia), and then their pneumococcal serotypes were compared. Nine hundred and nineteen patients with pneumococcal pneumonia were identified during the study period, including 327 (35.6%) cases with post-viral pneumococcal pneumonia and 592 (64.4%) cases with primary pneumococcal pneumonia. Overall, serotypes 3 and 19A were the most prevalent, followed by serotypes 19F, 6A, and 11A/11E. Although relatively uncommon (33 cases, 3.6%), infrequently colonizing invasive serotypes (4, 5, 7F/7A, 8, 9V/9A, 12F, and 18C) were significantly associated with preceding respiratory viral infections (69.7%, P<0.01). Multivariate analysis revealed several statistically significant risk factors for post-viral pneumococcal pneumonia: immunodeficiency (OR 1.66; 95% CI, 1.10-2.53), chronic lung diseases (OR 1.43; 95% CI, 1.09-1.93) and ICI serotypes (OR 4.66; 95% CI, 2.07-10.47).

CONCLUSIONS

Infrequently colonizing invasive serotypes would be more likely to cause pneumococcal pneumonia after preceding respiratory viral illness, particularly in patients with immunodeficiency or chronic lung diseases.

Role of pneumococcal vaccination in prevention of pneumococcal disease among adults in Singapore

The burden of disease associated with Streptococcus pneumoniae infection in adults can be considerable but is largely preventable through routine vaccination. Although substantial progress has been made with the recent licensure of the new vaccines for prevention of pneumonia in adults, vaccine uptake rates need to be improved significantly to tackle adult pneumococcal disease effectively. Increased education regarding pneumococcal disease and improved vaccine availability may contribute to a reduction in pneumococcal disease through increased vaccination rates. The increase in the elderly population in Singapore as well as globally makes intervention in reducing pneumococcal disease an important priority. Globally, all adult vaccines remain underused and family physicians give little priority to pneumococcal vaccination for adults in daily practice. Family physicians are specialists in preventive care and can be leaders in ensuring that adult patients get the full benefit of protection against vaccine-preventable diseases. They can play a key role in the immunization delivery of new and routine vaccines by educating the public on the risks and benefits associated with vaccines. Local recommendations by advisory groups on vaccination in adults will also help to tackle vaccine preventable diseases in adults.

Determining the cost-effectiveness of adult pneumococcal vaccination strategies

The 23-valent pneumococcal polysaccharide vaccine is known to be economically reasonable in adults. With the 13-valent pneumococcal conjugate vaccine (PCV13) now available, the question is whether 23-valent pneumococcal polysaccharide vaccine offers sufficient protection in adults compared with PCV13. Our cost-effectiveness analyses favor adult PCV13 use, but results depend largely on assumptions regarding PCV13 effectiveness in preventing non-bacteremic pneumococcal pneumonia and on herd immunity effects from childhood PCV13 use, neither of which are well characterized at present. An ongoing randomized trial of adult PCV13 use and future surveillance data should clarify these issues for some population groups, but in others, such as the immunocompromised, modeling that rigorously accounts for uncertainty can and should be used to assist policymakers in their decisions.

Preventing pneumococcal disease in the elderly: recent advances in vaccines and implications for clinical practice

Streptococcus pneumoniae remains a major cause of morbidity and mortality throughout the world. To date, after the introduction of routine childhood immunization, elderly people (i.e., persons aged 65 years or older) suffer the greatest burden of pneumococcal disease in developed countries. At present, two anti-pneumococcal vaccines are available for use in adults: the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 13-valent protein-polysaccharide conjugate vaccine (PCV13). This article reviews current data about the burden of pneumococcal disease in the elderly, as well as evidence for immunogenicity, clinical efficacy, and possible cost-effectiveness of both vaccines. The main advantage of PCV13 is that it may be more effective than PPV23, but a major limitation is that it is directed against strains that are likely to be greatly reduced in the population since its introduction in childhood immunization. The main disadvantage of PPV23 is that it may be less effective than PCV13 against vaccine-type infections but a major advantage is that it may provide protection against ten additional serotypes. To date, expert committees have not changed recommendations for pneumococcal vaccination in adults. However, at present, they are evaluating different alternatives (basically, maintaining PPV23, changing from PPV23 to PCV13 in some groups, or adding PCV13 for all or some target adult population subgroups). Critical data (clinical efficacy reported in ongoing trials and magnitude of indirect effects of pediatric PCV13 programs) needed to make a well-informed decision could be available during 2013. Considering all concerns over indirect effects and replacement strains following the use of polysaccharide-based vaccines, efforts should be directed toward developing vaccines, such as protein-based pneumococcal vaccines, with potential serotype-independent protection. Meanwhile, according to current recommendations, PPV23 should continue to be used for high-risk adults and all elderly people (with and without additional high-risk conditions). Although it is only moderately effective, it has a considerable serotype coverage and at-risk persons can benefit from the vaccination. High-risk individuals could also obtain a benefit from adding PCV13, but more data are needed before a universal recommendation can be made.

Adjuvant system AS02V enhances humoral and cellular immune responses to pneumococcal protein PhtD vaccine in healthy young and older adults: randomised, controlled trials

BACKGROUND

The protection elicited by polysaccharide pneumococcal vaccines against community-acquired pneumonia in older adults remains debatable. Alternative vaccine targets include well-conserved pneumococcal protein antigens, such as pneumococcal histidine triad protein D (PhtD).

OBJECTIVE

To evaluate humoral and cellular immune responses and safety/reactogenicity following immunisation with PhtD vaccine with or without adjuvant (alum or AS02V) in older (≥65 years) and young (18-45 years) healthy adults.

METHODS

Two phase I/II, single-blind, parallel-group studies were conducted in 150 older and 147 young adults. Participants were randomised to receive 2 doses (months 0 and 2) of PhtD 30 μg, PhtD 10 μg plus alum, PhtD 30 μg plus alum, PhtD 10 μg plus AS02V or PhtD 30 μg plus AS02V, or the 23-valent polysaccharide pneumococcal vaccine (23PPV) at month 0 with placebo (saline solution) at month 2. Safety/reactogenicity was assessed. PhtD-specific antibody, T cell and memory B cell responses were evaluated.

RESULTS

Solicited adverse events were more common in young participants and with adjuvanted vaccines. No vaccine-related serious adverse events were reported. Although anti-PhtD geometric mean antibody concentrations (GMCs) were consistently lower in the older adult cohort than in young adults, GMCs in the older cohort following PhtD 30 μg plus AS02V were comparable to those induced by plain PhtD or PhtD 30 μg plus alum in the young cohort. Compared with alum adjuvant, AS02V adjuvant system was associated with an increased frequency of PhtD-specific CD4 cells in both cohorts and a significantly higher specific memory B cell response in the older cohort, similar to responses obtained in the young cohort.

CONCLUSION

The improved immune response to PhtD vaccine containing the AS02V adjuvant system in comparison to alum suggests that the reduced immune response to vaccines in older adults can be partially restored to the response level observed in young adults. ClinicalTrials.gov identifiers: NCT00307528/NCT01767402.

Distribution of 13-valent pneumococcal conjugate vaccine Streptococcus pneumoniae serotypes in US adults aged ≥50 years with community-acquired pneumonia

BACKGROUND

Streptococcus pneumoniae causes a substantial proportion of community-acquired pneumonia (CAP) and healthcare-associated pneumonia (HCAP) in the United States. Limited data are available regarding the pneumococcal serotypes causing CAP and HCAP.

METHODS

Adults aged ≥ 50 years presenting to participating US hospitals with radiographically confirmed pneumonia between February 2010 and September 2011 were screened for inclusion. S. pneumoniae was identified using microbiological cultures, BinaxNOW® S. pneumoniae assay, or urine antigen detection (UAD) assay capable of detecting 13-valent pneumococcal conjugate vaccine (PCV13)-associated serotypes.

RESULTS

Among 710 subjects enrolled, the median age was 65.4 years; 54.2% of subjects were male, 22.4% of radiographically confirmed pneumonia cases were considered HCAP, and 96.6% of subjects were hospitalized. S. pneumoniae was detected in 98 subjects (13.8%) by any test, and PCV13-associated serotype(s) were identified by UAD in 78 (11.0%). Serotype 19A was most prevalent, followed by 7F/A, 3, and 5. Serotypes associated with 7-valent pneumococcal conjugate vaccine (PCV7) accounted for 25% of UAD-positive isolates.

CONCLUSIONS

Pneumococcal serotypes causing noninvasive pneumonia in adults may differ significantly from those causing invasive disease, with PCV7-associated serotypes overrepresented. Serotype 5, rarely seen in contemporary surveillance of invasive disease in the United States, substantially contributed to the observed cases of S. pneumoniae-positive CAP or HCAP.

Pneumococcal conjugate vaccination for older adults: Reply letter to Hollingsworth et al

Hollingsworth and Isturiz (1) have raised several questions about our earlier review of the use of pneumococcal conjugate (PCV) or polysaccharide (PPV) vaccine for older adults (i.e., ≥65 y of age). (2) They begin by citing two metaanalyses published in 2009 and 2013 that concluded that prevention of pneumococcal pneumonia could not be demonstrated for PPV. (3)(,) (4) They overlook my earlier review of five metaanalyses that was published in 2004. (5) This review showed that the study populations in prospective trials of PPV were often not representative of the populations of elderly and high-risk adults for whom PPV is recommended. Furthermore, the five metaanalyses often omitted clinical trials that should have been evaluated, included trials that should have been omitted, and frequently miscounted the numbers of subjects and outcome events in the individual clinical trials. More important, retrospective sample size calculations showed that none of the five metaanalyses included an adequate number of person years of observation to rule out false-negative results. The numbers speak for themselves and cannot be ignored. Simply put, metaanalyses of the PPV clinical trials will never tell us whether the vaccine prevents pneumococcal pneumonia or all-cause pneumonia in elderly and high-risk adults, and consequently they must be regarded as inconclusive and uninformative. Since 2004, only one small prospective clinical trial of PPV has been published (reviewed in 6). Nothing new has been added to our knowledge of PPV efficacy by the more recent metaanalyses. (3)(,) (4) Epidemiologists have reminded us that the lack of evidence of PPV efficacy is not evidence of its absence. The conclusions of our earlier review still stand. (5.)

National Advisory Groups and their role in immunization policy-making processes in European countries

During the twenty-first century, the development of national immunization programmes (NIP) has matured into robust processes where evidence-based methodologies and frameworks have increasingly been adopted. A key role in the decision-making and recommending processes is played by National Immunization Technical Advisory Groups (NITAGs). In a survey performed among European Union member states, Norway and Iceland, in February 2013, 85% of the 27 responding countries reported having established a NITAG, and of these, 45% have formal frameworks in place for the systematic development of vaccination recommendations. Independent of whether a formal framework is in place, common key factors are addressed by all NITAGs and also in countries without NITAGs. The four main factors addressed by all were: disease burden in the country, severity of the disease, vaccine effectiveness or efficacy, and vaccine safety at population level. Mathematical modelling and cost-effectiveness analyses are still not common tools. Differences in the relative weighting of these key factors, differences in data or assumptions on country-specific key factors, and differences in existing vaccination systems and financing, are likely to be reasons for differences in NITAG recommendations, and eventually NIPs, across Europe. Even if harmonization of NIPs is presently not a reasonable aim, systematic reviews and the development of mathematical/economic models could be performed at supranational level, thus sharing resources and easing the present work-load of NITAGs. Nevertheless, it has been argued that harmonization would ease central purchase of vaccines, thus reducing the price and increasing access to new vaccines.

How effective is vaccination in preventing pneumococcal disease?

Vaccination with a preparation that currently contains 23 pneumococcal capsular polysaccharides (PPV23) successfully reduces the risk of serious pneumococcal infection by an estimated 50% to 80%. Because infants and young children do not respond to polysaccharide antigens, a conjugated polysaccharide vaccine that first contained 7 capsule types (PCV7) and now contains 13 capsule types (PCV13) was developed for use in them. A single study in patients with AIDS showed protection against pneumococcal disease by PCV13, but not after PPV23. Based on these observations, the CDC has now recommended that immunocompromized adults receive PCV13 followed 8 weeks later by PPV23.

U.S. hospitalizations for pneumonia after a decade of pneumococcal vaccination

BACKGROUND

The introduction of 7-valent pneumococcal conjugate vaccine (PCV7) into the U.S. childhood immunization schedule in 2000 has substantially reduced the incidence of vaccine-serotype invasive pneumococcal disease in young children and in unvaccinated older children and adults. By 2004, hospitalizations associated with pneumonia from any cause had also declined markedly among young children. Because of concerns about increases in disease caused by nonvaccine serotypes, we wanted to determine whether the reduction in pneumonia-related hospitalizations among young children had been sustained through 2009 and whether such hospitalizations in older age groups had also declined.

METHODS

We estimated annual rates of hospitalization for pneumonia from any cause using the Nationwide Inpatient Sample database. The reason for hospitalization was classified as pneumonia if pneumonia was the first listed diagnosis or if it was listed after a first diagnosis of sepsis, meningitis, or empyema. Average annual rates of pneumonia-related hospitalizations from 1997 through 1999 (before the introduction of PCV7) and from 2007 through 2009 (well after its introduction) were used to estimate annual declines in hospitalizations due to pneumonia.

RESULTS

The annual rate of hospitalization for pneumonia among children younger than 2 years of age declined by 551.1 per 100,000 children (95% confidence interval [CI], 445.1 to 657.1), which translates to 47,000 fewer hospitalizations annually than expected on the basis of the rates before PCV7 was introduced. The rate for adults 85 years of age or older declined by 1300.8 per 100,000 (95% CI, 984.0 to 1617.6), which translates to 73,000 fewer hospitalizations annually. For the three age groups of 18 to 39 years, 65 to 74 years, and 75 to 84 years, the annual rate of hospitalization for pneumonia declined by 8.4 per 100,000 (95% CI, 0.6 to 16.2), 85.3 per 100,000 (95% CI, 7.0 to 163.6), and 359.8 per 100,000 (95% CI, 199.6 to 520.0), respectively. Overall, we estimated an age-adjusted annual reduction of 54.8 per 100,000 (95% CI, 41.0 to 68.5), or 168,000 fewer hospitalizations for pneumonia annually.

CONCLUSIONS

Declines in hospitalizations for childhood pneumonia were sustained during the decade after the introduction of PCV7. Substantial reductions in hospitalizations for pneumonia among adults were also observed. (Funded by the Centers for Disease Control and Prevention.).

Pneumococcal vaccination of older adults: conjugate or polysaccharide?

Invasive pneumococcal disease continues to be important problem for older adults. Pneumococcal polysaccharide vaccine (PPV23) has a clinical effectiveness of 43-81%, and following primary vaccination and revaccination, antibody responses last 5-10 y. Hyporesponsiveness to a second dose of vaccine has not been shown to be a significant problem. The use of pneumococcal conjugate vaccines (initially PCV7; more recently PCV13) has led to a dramatic fall in the incidence of conjugate vaccine-type invasive pneumococcal disease in children. Because PCVs are immunogenic in older adults, the question has arisen as to whether to also use PCVs in this age group. However, PCV vaccination of children has also reduced the incidence of conjugate vaccine-serotype disease in older adults, and so wherever PCVs are used in children, there is no epidemiological reason to vaccinate older adults with PCV. The cost-effectiveness of PPV for older adults has changed wherever PCVs have been used for children, and this needs to be periodically re-evaluated.

Pneumococcal vaccine and opsonic pneumococcal antibody

Streptococcus pneumoniae is a major human pathogen responsible for the majority of bacterial pneumonia cases as well as invasive pneumococcal diseases with high mortality and morbidity. Use of conjugate vaccines targeting the pneumococcal capsule has dramatically reduced the incidence of invasive diseases, and there are active efforts to further improve the conjugate vaccines. However, in children new pneumococcal vaccines can no longer be tested with placebo-based clinical trials because effective vaccines are currently available. Thus, vaccine studies must depend on surrogate markers of vaccine efficacy. Although traditional antibody levels (e.g., ELISA) are useful as a surrogate marker of protection, they have limitations, and a bioassay measuring the capacity of antibodies to opsonize pneumococci has been developed. This opsonophagocytosis assay (OPA) replicates the in vivo mechanism of antibody protection and should therefore better reflect protection by vaccine-induced antibodies. Technical improvements of OPA have made this bioassay rapid, multiplexed, and practical for analyzing small samples including those from children. Strong correlations between ELISA and OPA have been observed in many studies of young children. However, poor correlations have been found in some important clinical situations (such as determination of protection by cross-reactive antibodies) and populations (such as elderly adults and immunodeficient patients). In these settings, OPA has become a useful supplementary measure of pneumococcal vaccine immunogenicity. Current efforts to standardize OPA will further expand its uses.

Effectiveness of vaccination with 23-valent pneumococcal polysaccharide vaccine in preventing hospitalization with laboratory confirmed influenza during the 2009-2010 and 2010-2011 seasons

BACKGROUND

Since influenza predisposes to bacterial pneumonia caused by Streptococcus pneumoniae, studies have suggested that pneumococcal vaccination might reduce its occurrence during pandemics. We assessed the effectiveness of pneumococcal polysaccharide vaccination alone and in combination with influenza vaccination in preventing influenza hospitalization during the 2009-2010 pandemic wave and 2010-2011 influenza epidemic.

RESULTS

1187 cases and 2328 controls were included. The adjusted estimate of effectiveness of pneumococcal vaccination in preventing influenza hospitalization was 41% (95% CI 8-62) in all patients and 43% (95% CI 2-78) in patients aged ≥ 65 y. The adjusted effectiveness of dual PPV23 and influenza vaccination was 81% (95% CI 65-90) in all patients and 76% (95% CI 46-90) in patients aged ≥ 65 y. The adjusted effectiveness of influenza vaccination alone was 58% (95% CI 38-72).

METHODS

We conducted a multicenter case-control study in 36 Spanish hospitals. We selected patients aged ≥ 18 y hospitalized with confirmed influenza and two hospitalized controls per case, matched according to age, date of hospitalization and province of residence. Multivariate analysis was performed using conditional logistic regression. Subjects were considered vaccinated if they had received the pneumococcal or seasonal influenza vaccine>14 d (or>7 d for pandemic influenza vaccine) before the onset of symptoms (cases) or the onset of symptoms in matched cases (controls).

CONCLUSIONS

In elderly people and adults with chronic illness, pneumococcal vaccination may reduce hospitalizations during the influenza season. In people vaccinated with both the influenza and pneumococcal vaccines, the benefit in hospitalizations avoided was greater than in those vaccinated only against influenza.