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We evaluated invasive pneumococcal disease (IPD) during 8 years of infant pneumococcal conjugate vaccine (PCV) programs using 10-valent (PCV10) and 13-valent (PCV13) vaccines in 10 countries in Europe. IPD incidence declined during 2011-2014 but increased during 2015-2018 in all age groups. From the 7-valent PCV period to 2018, IPD incidence declined by 42% in children <5 years of age, 32% in persons 5-64 years of age, and 7% in persons >65 years of age; non-PCV13 serotype incidence increased by 111%, 63%, and 84%, respectively, for these groups. Trends were similar in countries using PCV13 or PCV10, despite different serotype distribution. In 2018, serotypes in the 15-valent and 20-valent PCVs represented one third of cases in children <5 years of age and two thirds of cases in persons >65 years of age. Non-PCV13 serotype increases reduced the overall effect of childhood PCV10/PCV13 programs on IPD. New vaccines providing broader serotype protection are needed.

Streptococcus pneumoniae (pneumococcus) is a major cause of worldwide mortality and morbidity, and to a large extent is vaccine-preventable. Nasopharyngeal carriage of pneumococcus precedes disease and is the source of pneumococcal spread between people. The use of vaccine effect on carriage as part of the vaccine licensure and post-vaccine introduction evaluation could facilitate and expand the licensure of new, life-saving pneumococcal vaccines and enable a comprehensive estimate of population effects after vaccine introduction. The authors provide a review of the evidence supporting pneumococcal carriage at the individual level as an immediate and necessary precursor to pneumococcal disease. Based on such a causal link between carriage and disease, the authors emphasize the role of information on pneumococcal carriage in vaccine trials and in public health decision-making.

Pneumococcal conjugate vaccine 10 (PCV10) and pneumococcal conjugate vaccine 13 (PCV13), are used in childhood immunization programs worldwide, but direct comparisons of impacts against invasive pneumococcal disease (IPD) in equivalent populations have not been performed. We compared the vaccines (prevaccination 2007-2009 vs postvaccination 2013-2016) in Sweden, where the 21 counties use either PCV10 or PCV13 (introduced 2009-2010). All IPD episodes (n = 16992) were recorded in Sweden during 2005-2016. Of 14 186 isolates from 2007-2016, 13 468 (94.9%) were characterized with serotyping and 12 235 (86.2%) with antibiotic susceptibility. Poisson models assessed changes in incidence over time. Invasive pneumococcal disease incidences decreased between 2005 and 2016 in vaccinated children (by 68.5%), and in the whole population (by 13.5%), but not among the elderly (increased by 2%) due to a substantial increase in nonvaccine types (NVTs). In 2016, NVTs constituted 72% of IPD cases in the elderly. Serotype 6A declined in PCV10 and PCV13 counties, whereas serotype 19A increased in PCV10 counties. There was no effect against serotype 3. Cross-protection was found between 6B and 6A but not between 19F and 19A. Serotype 6C increased in PCV10 counties, but not in PCV13 counties, suggesting cross-protection with 6A, which is included in PCV13. In the elderly, the increase in NVTs, excluding 6C, was more pronounced in PCV13 counties. The overall impact of IPD incidences was not statistically different irrespective of vaccine used. The incidence of serotypes, where the effect of the vaccines differed, will influence the cost-effectiveness of which vaccine to use in immunization programs. The dominance of NVTs suggests a limited effect of current pediatric PCVs against IPD in the elderly.

•This is a systemic literature review on PCV indirect (herd) impact in adults.•Adults IPD and pneumonia rates decreased in most countries post-PCV introduction.•Herd protection depended on PCV uptake rates and time from PCV implementation.•Adults >65years old seem to benefit the most from PCV introduction. Pneumococcal diseases are major causes of morbidity among adults, especially those over 50years of age. While pneumococcal conjugated vaccines (PCV’s) impact on pneumococcal disease rates among children is well established, the extent of its impact on adult pneumococcal related illness remains unclear. The aim of this systematic literature review was to describe the impact of PCV introduction to childhood national immunization programs worldwide on PCV-naive adult population. A systematic literature search was performed using the PubMed database. The search was limited to articles written in English and published between January 2000 and February 2016. Studies evaluating pneumococcal disease rates in individuals over 5years of age were included. Independent extraction of articles was performed by the two authors. Search terms included: Pneumococcal conjugated vaccine, herd, indirect, adults, and pneumonia. Forty-nine articles meeting the selection criteria were identified, 39 regarding invasive pneumococcal disease (IPD, one on meningitis only), 8 regarding pneumonia, and 2 on both IPD and pneumonia. The majority of reports were from the US, UK and Canada. Considerable variability in the data sources, quality and completeness was observed. While most studies reported either statistically significant reduction or insignificant changes in IPD and pneumonia disease rates in adults following PCV nationwide implementation, few studies reported statistically significant increase in pneumococcal disease rates, these were mainly from countries with low PCV coverage rates and/or inadequate surveillance. Invasive pneumococcal diseases and pneumonia rates among the adult population decreased in most countries following PCV introduction into the NIP. This indirect effect on older population seems to be dependent on PCV coverage rates and time from PCV nationwide implementation. Adults >65years old seem to benefit the most from PCV introduction.

In Greece, pneumococcal conjugate vaccines (PCVs) became sequentially available: 7-valent in October 2004, 10-valent in May 2009, 13-valent in June 2010 and 15-valent in March 2023; soon after availability all vaccines were incorporated in the National Ιmmunization Program except for PCV7 which was implemented in January 2006. Since July 2010, PCV13 has been the most commonly used PCV. Surveillance at a regional and a national level is a valuable tool to monitor the impact of PCVs. At the University General Hospital of Larissa (single academic tertiary care referral center for Central Greece) we prospectively obtained samples from 0 to 15-year-old children consequently diagnosed with invasive pneumococcal disease (IPD) or acute otitis media (AOM) with spontaneous perforation of the tympanic membrane (SPTM) during three time periods: the PCV7 (2005–2010), the early-mid PCV13 (2011–2016) and the late PCV13 (2017–2024) periods. Pneumococci were serotyped by capsular swelling. PCR was applied on pleural fluid and CSF specimens. A total of 106 (61 IPD and 45 AOM with SPTM) serotype-evaluable samples were obtained. Serotypes 19A and 19F peaked in 2005–2010 and decreased thereafter. Increased number of IPD cases due to serotype 3 were noted in the 2011–2016 and 2017–2024 periods. The emergence of non-PCV13 serotypes in IPD and AOM with SPTM was noted in the late PCV13 period. In 2017–2024 the most common serotypes responsible for IPD were 3 and 12F. The projected additional protection from IPD, beyond that of PCV13, offered by PCV15 and PCV20 during 2017–2024 was 10 % and 30 %, respectively. The respective additional protection from AOM offered by the two vaccines was 0 % and 21.4 %. Our findings in Central Greece suggest that PCVs of increasing valency are expected to provide substantial additional coverage for pneumococcal disease as compared to PCV13.

•PCV10 reduced IPD caused by vaccine serotypes of Streptococcus pneumoniae.•PCV10 reduced IPD by vaccine serotypes in the non-targeted population.•IPD by serotypes 3, 6C, and 19A increased after the introduction of PCV10. In March 2010, the 10-valent pneumococcal conjugate vaccine (PCV10) was introduced into the routine immunization program in Brazil. We describe the pneumococcal serotypes that caused invasive pneumococcal diseases (IPD) before and after the introduction of PCV10 using data from a national laboratory-based surveillance system. We compared the prevalence of vaccine types (VT) and non-vaccine types (NVT) of Streptococcus pneumoniae in three periods, pre-PCV10 (January/2005-December/2009), early post-PCV10 (January/2010-December/2013), and late post-PCV10 (January/2014-December/2015), by episode in meningitis and non-meningitis cases and by age group. Changes in serotype prevalence in the early and late post-PCV10 periods were determined using pre-PCV10 period as a reference. A total of 8971 IPD isolates from patients aged 2 months to 99 years were analyzed. In the late post-PCV10 period, the VT-IPD reduction in the 2-month to 4-year age group was 83.4% for meningitis and 87.4% for non-meningitis cases; in the age groups 5–17 years, 18–64 years, and ≥65 years, VT declined by 56.1%, 54.1%, and 47.4%, respectively, in meningitis cases, and by 60.9%, 47.7%, and 53.4%, respectively, in non-meningitis cases. NVT-IPD increased throughout the study period, driven mainly by serotypes 3, 6C, and 19A, which remained the predominant types causing IPD in the late post-PCV10 period. We observed direct and indirect PCV10 protection against IPD caused by VT and a shift in the distribution of serotypes 5 years after the introduction of PCV10. Continued IPD surveillance is needed to evaluate the sustainability of the high prevalence of serotypes 3, 6C, and 19A, which were not included in PCV10.

The 13-valent pneumococcal conjugate vaccine (PCV13) is the only licensed PCV with serotype 3 polysaccharide in its formulation. Postlicensure PCV13 effectiveness studies against serotype 3 invasive pneumococcal disease (IPD) in children have shown inconsistent results. We performed a systematic review and meta-analysis of observational studies to assess PCV13 vaccine effectiveness (VE) for serotype 3 IPD in children. We systematically searched PubMed, Embase, and the Cochrane library for studies published before 14 August 2017. We identified 4 published studies and 2 conference posters that provided PCV13 VE estimates stratified by serotype. The pooled PCV13 VE against serotype 3 IPD from the random-effects meta-analysis was 63.5% (95% confidence interval [CI], 37.3%–89.7%). A sensitivity analysis including conference posters gave a pooled VE estimate of 72.4% (95% CI, 56.7%–88.0%). The pooled data from case-control studies with similar methodologies and high quality support direct PCV13 protection against serotype 3 IPD in children.

The incidence of IPD in adults, while largely decreased from indirect effect of pediatric PCVs, remains high. To describe differences in the expected serotype coverage and incidence of IPD by V116, a novel adult-specific PCV, and other licensed PCVs used in adults. We used national IPD surveillance serotype distribution data from 7 countries (US, Canada, UK, Germany, France, Spain, and Australia). We calculated serotype coverage offered by V116 and PCV20 in adults 65+ (or 60+) years old in 2022 (2019 for UK, France). For all countries except Germany, we reported incidence/notification rates of IPD due to serotypes in V116 versus other PCVs in 2019. As an example, we estimated annual numbers of US cases potentially prevented, assuming 100 % vaccine efficacy and uptake for both vaccines. From 7 countries, coverage conferred by V116 in adults 65+ in 2019–2022 ranged from 66 %–88 % of IPD cases while PCV20 coverage ranged from 50 %–66 %. The incidence of IPD among adults 65+ caused by serotypes included in V116 is higher in all six countries compared to other PCVs in 2019. In US, the annual incidence of IPD (per 100,000) among 65+ was 24; the incidence caused by serotypes in V116 was 20 cases compared to 12 from PCV20 serotypes. Of the estimated total 12,800 annual IPD cases in 2019 in the US, V116 could potentially prevent ∼8200 cases compared to ∼5000 by PCV20. Based on IPD surveillance data from key countries, serotype coverage by V116 was ∼16–33 % higher than that by PCV20 among adults 65+ years in 2022 (data for UK, France from 2019). V116 includes serotypes responsible for the majority of IPD and is expected to prevent more IPD cases than PCV20 among 65+.

Vaccine-serotype (VT) invasive pneumococcal disease (IPD) rates declined substantially following introduction of 7-valent pneumococcal conjugate vaccine (PCV7) into national immunization programs. Increases in non-vaccine-serotype (NVT) IPD rates occurred in some sites, presumably representing serotype replacement. We used a standardized approach to describe serotype-specific IPD changes among multiple sites after PCV7 introduction. Of 32 IPD surveillance datasets received, we identified 21 eligible databases with rate data ≥ 2 years before and ≥ 1 year after PCV7 introduction. Expected annual rates of IPD absent PCV7 introduction were estimated by extrapolation using either Poisson regression modeling of pre-PCV7 rates or averaging pre-PCV7 rates. To estimate whether changes in rates had occurred following PCV7 introduction, we calculated site specific rate ratios by dividing observed by expected IPD rates for each post-PCV7 year. We calculated summary rate ratios (RRs) using random effects meta-analysis. For children <5 years old, overall IPD decreased by year 1 post-PCV7 (RR 0.55, 95% CI 0.46-0.65) and remained relatively stable through year 7 (RR 0.49, 95% CI 0.35-0.68). Point estimates for VT IPD decreased annually through year 7 (RR 0.03, 95% CI 0.01-0.10), while NVT IPD increased (year 7 RR 2.81, 95% CI 2.12-3.71). Among adults, decreases in overall IPD also occurred but were smaller and more variable by site than among children. At year 7 after introduction, significant reductions were observed (18-49 year-olds [RR 0.52, 95% CI 0.29-0.91], 50-64 year-olds [RR 0.84, 95% CI 0.77-0.93], and ≥ 65 year-olds [RR 0.74, 95% CI 0.58-0.95]). Consistent and significant decreases in both overall and VT IPD in children occurred quickly and were sustained for 7 years after PCV7 introduction, supporting use of PCVs. Increases in NVT IPD occurred in most sites, with variable magnitude. These findings may not represent the experience in low-income countries or the effects after introduction of higher valency PCVs. High-quality, population-based surveillance of serotype-specific IPD rates is needed to monitor vaccine impact as more countries, including low-income countries, introduce PCVs and as higher valency PCVs are used. Please see later in the article for the Editors' Summary.

Background. The 7-valent pneumococcal conjugate (PCV7) vaccine's impact on invasive pneumococcal disease (IPD) is well described, but few reports exist on the additional impact of the 13-valent vaccine (PCV13). Methods. We calculated the IPD incidence across all ages in a surveillance project following implementation of PCV7 (in September 2006) and PCV13 (in April 2010) in children aged < 2 years (11 hospitals; 4935 cases). Results. The overall incidence decreased from 10 cases/100 000 persons per year in 1996-1997 to 8 cases/100 000 persons per year in 2007-2008 and 7 cases/100 000 in 2012-2013. Declines were greater in children aged < 2 years (from 37 cases/100 000 in 1996-1997 to 29 and 14 cases/100 000 in 2007-2008 and 2012-2013, respectively). The incidence of IPD due to PCV7 serotypes decreased in all ages after PCV7 introduction (P< .001), whereas the incidence of IPD due to the additional 6 serotypes in PCV13 and to nonvaccine types (NVTs) increased in children aged > 2 years (P< .001 for both comparisons). The incidence of IPD due to the 6 additional serotypes in PCV13 declined significantly after PCV13 introduction in all ages (P < .01), and the incidence of IPD due to NVTs declined significantly in children aged > 2 years (P = .003). In 2011-2013, the overall incidences of IPD due to PCV7 serotypes, the 6 additional serotypes in PCV13, and NVTs were 0.3, 2.8, and 4.4 cases/100 000; the incidences among children aged ≥ 2 years were 0.9, -2.4, and 10.8 cases/100 000, respectively. Conclusions. The annual incidence of IPD due to vaccine serotypes (1-3 cases/100 000) among children aged < 2 years and nontarget groups demonstrates the success of PCV7 and PCV13. A substantially higher incidence of IPD due to NVTs indicates the importance of ongoing surveillance and extension of vaccine polyvalency.