Pneumococcal Serotype Replacement Research Articles

The impact of pneumococcal serotype replacement on the effectiveness of a national immunization program: a population-based active surveillance cohort study in New Zealand

In Aotearoa New Zealand (NZ) PCV7 was introduced in 2008, then PCV10 in 2011 and PCV13 in 2014. In 2017 PCV10 was re-introduced, replacing PCV13. In the present study, we investigate the resultant rapidly changing invasive pneumococcal disease (IPD) epidemiology. We compare the IPD incidence rate ratio (IRR) in NZ (2022 versus 2020) with other countries, and describe the IPD epidemiology (including trends in overall IPD and serotype 19A, and antimicrobial resistance) within NZ. Additionally, we performed a genomic-epidemiology investigation identifying the most common 19A sequence types and associated risk factors. Though IPD incidence rates have increased in the US and Australia (2021-22) after declines in 2020, in NZ the incidence rate is the highest since 2011 with a significantly higher IRR than US (p<0.01). Incidence rates among children <2 and adults 65 or over in 2022 are the highest since 2009, driven by significant increases of serotype 19A (p=0.01). Māori and Pacific peoples are experiencing the highest rates since 2009. Further, penicillin resistance among 19A isolates has increased from 39% (2012) to 84% (2021) (p=0.02). Genomic sequencing identified the more virulent ST-2062 as most common among 19A isolates sequenced, increasing from 5% (2010) to 55% (2022). With very high incidence rates of IPD in NZ, inadequate protection against 19A, increasing resistance, and a more virulent 19A clade, targeted public health campaigns and increased PCV13 availability are needed. The NZ Ministry of Health funds IPD surveillance and typing in NZ.

Whole-cell pneumococcal vaccines: a future-proof approach to overcoming pneumococcal serotype replacement

Whole-cell pneumococcal vaccines: a future-proof approach to overcoming pneumococcal serotype replacement

Global Landscape Review of Serotype-Specific Invasive Pneumococcal Disease Surveillance among Countries Using PCV10/13: The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) Project.

Serotype-specific surveillance for invasive pneumococcal disease (IPD) is essential for assessing the impact of 10- and 13-valent pneumococcal conjugate vaccines (PCV10/13). The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) project aimed to evaluate the global evidence to estimate the impact of PCV10/13 by age, product, schedule, and syndrome. Here we systematically characterize and summarize the global landscape of routine serotype-specific IPD surveillance in PCV10/13-using countries and describe the subset that are included in PSERENADE. Of 138 countries using PCV10/13 as of 2018, we identified 109 with IPD surveillance systems, 76 of which met PSERENADE data collection eligibility criteria. PSERENADE received data from most (n = 63, 82.9%), yielding 240,639 post-PCV10/13 introduction IPD cases. Pediatric and adult surveillance was represented from all geographic regions but was limited from lower income and high-burden countries. In PSERENADE, 18 sites evaluated PCV10, 42 PCV13, and 17 both; 17 sites used a 3 + 0 schedule, 38 used 2 + 1, 13 used 3 + 1, and 9 used mixed schedules. With such a sizeable and generally representative dataset, PSERENADE will be able to conduct robust analyses to estimate PCV impact and inform policy at national and global levels regarding adult immunization, schedule, and product choice, including for higher valency PCVs on the horizon.

Serotype Distribution of Remaining Pneumococcal Meningitis in the Mature PCV10/13 Period: Findings from the PSERENADE Project.

Pneumococcal conjugate vaccine (PCV) introduction has reduced pneumococcal meningitis incidence. The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) project described the serotype distribution of remaining pneumococcal meningitis in countries using PCV10/13 for least 5–7 years with primary series uptake above 70%. The distribution was estimated using a multinomial Dirichlet regression model, stratified by PCV product and age. In PCV10-using sites (N = 8; cases = 1141), PCV10 types caused 5% of cases <5 years of age and 15% among ≥5 years; the top serotypes were 19A, 6C, and 3, together causing 42% of cases <5 years and 37% ≥5 years. In PCV13-using sites (N = 32; cases = 4503), PCV13 types caused 14% in <5 and 26% in ≥5 years; 4% and 13%, respectively, were serotype 3. Among the top serotypes are five (15BC, 8, 12F, 10A, and 22F) included in higher-valency PCVs under evaluation. Other top serotypes (24F, 23B, and 23A) are not in any known investigational product. In countries with mature vaccination programs, the proportion of pneumococcal meningitis caused by vaccine-in-use serotypes is lower (≤26% across all ages) than pre-PCV (≥70% in children). Higher-valency PCVs under evaluation target over half of remaining pneumococcal meningitis cases, but questions remain regarding generalizability to the African meningitis belt where additional data are needed.

Changes in Invasive Pneumococcal Disease Caused by Streptococcus pneumoniae Serotype 1 Following Introduction of PCV10 and PCV13: Findings from the PSERENADE Project.

Streptococcus pneumoniae serotype 1 (ST1) was an important cause of invasive pneumococcal disease (IPD) globally before the introduction of pneumococcal conjugate vaccines (PCVs) containing ST1 antigen. The Pneumococcal Serotype Replacement and Distribution Estimation (PSERENADE) project gathered ST1 IPD surveillance data from sites globally and aimed to estimate PCV10/13 impact on ST1 IPD incidence. We estimated ST1 IPD incidence rate ratios (IRRs) comparing the pre-PCV10/13 period to each post-PCV10/13 year by site using a Bayesian multi-level, mixed-effects Poisson regression and all-site IRRs using a linear mixed-effects regression (N = 45 sites). Following PCV10/13 introduction, the incidence rate (IR) of ST1 IPD declined among all ages. After six years of PCV10/13 use, the all-site IRR was 0.05 (95% credibility interval 0.04–0.06) for all ages, 0.05 (0.04–0.05) for <5 years of age, 0.08 (0.06–0.09) for 5–17 years, 0.06 (0.05–0.08) for 18–49 years, 0.06 (0.05–0.07) for 50–64 years, and 0.05 (0.04–0.06) for ≥65 years. PCV10/13 use in infant immunization programs was followed by a 95% reduction in ST1 IPD in all ages after approximately 6 years. Limited data availability from the highest ST1 disease burden countries using a 3 + 0 schedule constrains generalizability and data from these settings are needed.

Efficacy of a Protein Vaccine and a Conjugate Vaccine Against Co-colonization with Vaccine-type and Non-vaccine Type Pneumococci in Mice.

Widespread use of pneumococcal conjugate vaccines (PCVs) has led to substitution of vaccine-type (VT) strains by non-vaccine type (NVT) strains in nasopharyngeal carriage. We compared the efficacy of PCV13 and a nasal protein formulation containing pneumococcal surface protein A (PspA) adjuvanted with the whole-cell pertussis vaccine (wP) in the protection against co-colonization challenge models in mice with VT and NVT strains expressing different PspAs. Immunized mice were challenged with two different mixtures: i. VT4 (PspA3) + NVT33 (PspA1) and ii. VT23F (PspA2) + NVT15B/C (PspA4). Results from the first mixture showed a reduction in loads of VT4 strain in the nasopharynx of mice immunized with PCV13. A statistical difference between the loads of the VT and NVT strains was observed, indicating a competitive advantage for the NVT strain in PCV13-immunized animals. In the second mixture, no reduction was observed for the VT23F strain, probably due to low levels of anti-23F polysaccharide IgG induced by PCV13. Interestingly, a combination of the PspA formulation containing wP with PCV13 led to a reduction in colonization with both strains of the two mixtures tested, similar to the groups immunized nasally with wP or PspA plus wP. These results indicate that a combination of vaccines may be a useful strategy to overcome pneumococcal serotype replacement.

Differences in the Impact of Pneumococcal Serotype Replacement in Individuals With and Without Underlying Medical Conditions.

Pneumococcal conjugate vaccines (PCVs) have had a well-documented impact on the incidence of invasive pneumococcal disease (IPD). However, declines in IPD due to vaccine-targeted serotypes have been partially offset by increases in IPD due to nonvaccine serotypes (NVTs). The goal of this study was to quantify serotype-specific changes in the incidence of IPD that occurred in different age groups, with or without certain comorbidities, following the introduction of 7-valent pneumococcal conjugate vaccine (PCV7) and 13-valent pneumococcal conjugate vaccine (PCV13) in the childhood vaccination program in Denmark. We used nationwide surveillance data for IPD and a hierarchical Bayesian regression framework to estimate changes in the incidence of IPD associated with the introduction of PCV7 (2007) and PCV13 (2010) while controlling for serotype-specific epidemic cycles and unrelated secular trends. Following the introduction of PCV7 and PCV13 in children, the net impact of serotype replacement varied considerably by age group and comorbidities. Differences in the magnitude of serotype replacement were due to variations in the incidence of NVTs in the different risk groups before the introduction of PCVs. The relative increases in the incidence of IPD caused by specific NVTs did not differ appreciably between risk groups in the postvaccination period. Serotype replacement offset a greater proportion of the benefit of PCVs in strata in which the NVTs comprised a larger proportion of cases prior to the introduction of the vaccines. These findings could help to predict the impact of next-generation PCVs in specific risk groups.

Serotype distribution of Streptococcus pneumoniae isolated from adult respiratory tract infections in nationwide Japanese surveillances from 2006 to 2014.

Reports on the efficacy of pneumococcal conjugate vaccines (PCVs) have been received from many countries. However, in countries where the 7-valent PCV (PCV7) and 13-valent PCV (PCV13) were introduced, overall coverage of the serotypes by the vaccine gradually decreased due to pneumococcal serotype replacement. The aim of this study is to assess the distribution of pneumococcal serotypes and to also provide basic data on adult respiratory infection in Japan. We analyzed 1086 Streptococcus pneumoniae strains that had been isolated from respiratory tract infection specimens in adult patients from 2006 to 2014. Capsular typing was performed by the Quellung reaction and multiplex PCR. Among all 1086 strains, serotype 3 was the most common and was identified in 160 strains (14.7%), followed by serotypes 19F, 6B, 19A and 23F. From 2006-10 to 2012-14, the coverage rate of PCV7 tended to gradually decrease. Particularly, serotypes 6B and 19F of penicillin non-susceptible strains decreased. On the other hand, serotypes 19A and 15A of penicillin non-susceptible strains increased. However, coverage by PCV13 of penicillin-resistant S.pneumoniae (PRSP) (penicillin G minimum inhibitory concentration ≥2μg/mL) remained high (88.7% [2006-10], 88.0% [2012-14]). In Japan, PCV13 vaccination of adults became available from June 2014. Our study demonstrated that most PRSP (88.0%) still remain covered by PCV13. At present, the introduction of PCV13 in adult clinical practice seems to be highly significant. However, there is a possibility that the distribution has been changing, and careful screening should be continued in the future.

Continuous Pneumococcal Invasive Disease Reduction, High Impact on Pneumococcal Empyemas and Meningitis, and Serotype 19A Disappearance Following PCV-13 Vaccination in Children: Eleven and a Half Years of Active Surveillance in a Mexican Hospital on the U.S. Border

BackgroundThe Tijuana, Mexico and San Diego, California, is the world’s most transited frontier. We have previously published pneumococcal serotype replacement following PCV-7 introduction, especially by serotypes 19-A, 3 and 6A/C. Since May/2012 universal vaccination with PCV-13 was introduced for all children. This study analyzes the effectiveness of PCV-13 after its implementation in the region.MethodsSince October/2005 until March/2017 (11.5 years) we underwent an active surveillance for all Invasive Pneumococcal Diseases (IPD) in children < 16 years admitted at the Tijuana General Hospital. Only culture-confirmed cases were included. Following identification, serotyping was performed using the Quellung Reaction (Statens Serum Institute® Copenhagen, Denmark). Descriptive analysis was performed using Excel®.ResultsFifty-seven cases of confirmed IPD were found. Clinical diagnosis were pleural empyemas (PPE) (45.6%), meningitis (PM) (28%), otomastoiditis (15.7%), only sepsis (7%), and bacteremic pneumonia (3.5%). Median age was of 3.9 years (2 days – 15.9 years), median hospitalization days was of 14 (1–90). Overall mortality was of 6 (10.5%). Following PCV13 introduction there was a decreased on overall IPD mortality by 73.29%, overall IPD by 68%, PPE by 68.1%, and PM by 55.4%. However, during 2015–16, we had three PM cases, two of which were immunocompromised patients, and none vaccinated with PCV13. From an average of 1.75 yearly cases due to pneumococcal serotype 19-A before PCV13 implementation, there had been no patients with IPD’s caused by this serotype. (See Figure 1). After PCV13 vaccination, serotypes associated with IPD cases had been as follow: Two 22F, and one each by 6A, 18C, 3, 7F, 15, 7B, 35B, 24F and 33F.ConclusionThis is the first Mexican study based on active surveillance that shows consistent effectiveness of PCV-13 on reduction of overall IPD, disappearance of pneumococcal serotype 19-A, and strong impact on PPE in children. Effectiveness on PM is still above 50%, however, during 2015–16 there had been three cases, but with particular conditions (immunodeficiencies and no vaccination). Continuous active surveillance is mandatory.Disclosures All authors: No reported disclosures.

Pneumonia hospitalisations in Scotland following the introduction of pneumococcal conjugate vaccination in young children.

BackgroundScotland introduced PCV7 and PCV13 immunisation in young children in 2006 and 2010 respectively. One recent study from the United States reported a decrease in hospitalisation rates for all-cause pneumonia most notably in adults older than 75 years of age following PCV7 introduction in the US child population. We aimed to examine the effect of PCV7 and PCV13 on hospitalisation rates for all-cause pneumonia across all age groups in Scotland.MethodsWe linked hospital records and death certification datasets for the entire Scottish population for the period 2000 to 2012. We included all cases where the primary / secondary diagnosis was pneumonia. Differences in hospital admission rates for pneumonia by age group were calculated using the difference in average annual rates for each period.ResultsWe estimated that all-cause pneumonia hospitalisation rates in children <2 years decreased by about 30 % in the post-PCV-13 period compared with the pre-PCV period. However, in adults aged 75–84 years and ≥85 years, all-cause pneumonia hospitalisation rates increased by 63 and 46 % respectively in the post-PCV 13 period compared to the pre-PCV period. This resulted in an additional 7000 hospitalisations across all age groups in Scotland in 2012 about half of which were in adults >75 years. At the same time, the median length of hospital stay decreased by a third in children <2 years and by about 20 % in adults >75 years in the post-PCV13 period compared to the pre-PCV period. Additionally, there was an 11 % reduction in deaths due to all-cause pneumonia, and 30 % reduction in pneumococcal hospitalisations across all age groups in the post-PCV13 period compared with pre-PCV period.DiscussionThe modest and sustained decline in the rates of hospitalisation for all-cause pneumonia in children and the reduction in proportion of pneumonia hospitalisations in children coded as pneumococcal disease in the post-PCV period should alleviate concerns that pneumococcal serotype replacement may have resulted in an increased pneumonia burden in this age group. The indirect impact of child PCV immunisation in those not vaccinated (in terms of reduction in all-cause pneumonia hospitalisations in the elderly) has not been seen in Scotland. Our results are likely to be confounded by changes in clinical coding and healthcare practices over the same period.ConclusionsOur results illustrate that health care planners cannot, with confidence, predict indirect PCV vaccine impacts on hospitalisations. IPD surveillance across all age groups is needed to assess the indirect effects of PCV in the community.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1693-x) contains supplementary material, which is available to authorized users.

Epidemiological Markers for Interactions Among Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus in Upper Respiratory Tract Carriage.

Cocolonization by Streptococcus pneumoniae and Haemophilus influenzae among children has been noted in numerous studies, as has an inverse relationship involving colonization with these species and Staphylococcus aureus. Interactions among these pathogens could mediate unanticipated outcomes of clinical interventions, including changes in H. influenzae and S. aureus disease incidence following pneumococcal vaccine introduction. However, it remains unclear whether cocolonization patterns represent true interspecies interactions or whether they result from confounding factors. We investigated polymicrobial carriage using longitudinal data from 369 Bedouin children and 400 Jewish children in Israel who were enrolled in a 7-valent pneumococcal conjugate vaccine (PCV7) trial. Children were swabbed 10 times between 2 and 30 months of age. The pathogens followed distinct age and seasonal distributions, but polymicrobial carriage associations persisted after controlling for these and other confounding factors. Receipt of PCV7 resulted in pneumococcal serotype replacement but did not influence total carriage of S. pneumoniae, H. influenzae, or S. aureus. The fact that S. pneumoniae, H. influenzae, and S. aureus polymicrobial carriage patterns do not result from confounding by age and season supports the idea of active interspecies interactions. However, pneumococcal serotype replacement may prevent changes in H. influenzae and S. aureus carriage among PCV7 recipients.

Five winters of pneumococcal serotype replacement in UK carriage following PCV introduction

The seven-valent pneumococcal conjugate vaccine (PCV7) was added to the UK national immunisation programme in September 2006. PCV13 replaced PCV7 in April 2010. As carriage precedes disease cases this study collected carried pneumococci from children each winter from 2006/7 to 2010/11 over PCV introduction. Conventional microbiology and whole genome sequencing were utilised to characterise pneumococcal strains.Overall prevalence of pneumococcal carriage remained stable. Vaccine serotypes (VT) decreased (p<0.0001) with concomitant increases in non-vaccine serotypes (NVT). In winter 2010/11 only one isolate of PCV7 VT was observed (6B). PCV13 unique VTs decreased between winters immediately preceding and following PCV13 introduction (p=0.04). Significant decreases for VTs 6B, 19F, 23F (PCV7) and 6A (PCV13) and increases for NVT 21, 23B, 33F and 35F were detected. The serotype replacement was accompanied by parallel changes in genotype prevalence for associated sequence types with clonal expansion contributing to replacement. By winter 2010/11, serotype coverage of PCV7 and PCV13 was 1% and 11% respectively.VT replacement was observed for PCV7 and PCV13 serotypes. Conjugate vaccine design and use requires continuous monitoring and revision.

Changes in nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis among healthy children attending a day-care centre before and after official financial support for the 7-valent pneumococcal conjugate vaccine and H. influenzae type b vaccine in Japan

The 7-valent pneumococcal conjugate vaccine (PCV7) and Haemophilus influenzae type b (Hib) vaccine reduce nasopharyngeal carriage of vaccine-type bacteria, which may in turn influence the presence of other nasopharyngeal bacterial pathogens. To investigate this possibility, nasopharyngeal carriage of potential pathogens was examined before and after official financial support was provided to offer the PCV7 and Hib vaccines in healthy children attending a day care centre in Japan during 2011-2012. Despite a virtual disappearance of PCV7 serotypes over time, the overall pneumococcal carriage rate remained unchanged. Although others have reported an increase in PCV13 serotypes following PCV7 vaccination, only non-PCV13 serotypes were observed to have increased in this study. The majority of H.influenzae isolates were non-typeable and Hib was not found. Our data identified an unexpected pattern of pneumococcal serotype replacement following PCV7. Continuous monitoring of pneumococcal carriage is important for decisions regarding the future of national vaccination policy in Japan.

What is the best way to use conjugate vaccines?

The present review discusses recent advances, challenges and opportunities for the best use of conjugate vaccines now and in the future. Direct protection in young children may be short-lived and programme effectiveness may depend heavily on indirect protection (herd immunity). Pneumococcal carriage serotype replacement has been widely reported following vaccine implementation. Use of pneumococcal conjugate vaccines is being trialled in the elderly. Vaccination in west Africa against Neisseria meningitidis serogroup A (Men A), a new monovalent conjugate vaccine, was commenced in December 2010. New conjugate vaccines against, for example, Salmonella typhi and Streptococcus agalactiae, are being developed and tested in clinical trials. Conjugate vaccines have been extensively used to immunize children, resulting in significant decreases in childhood morbidity and mortality. Since their introduction, evidence has grown that protection against disease is due to both direct and indirect protection (herd immunity). The optimization of priming and booster dose regimens in existing paediatric vaccination programmes, aiming for maximal and sustained direct and indirect protection using as few doses per child as possible, may broaden conjugate vaccine impact and augment cost-effectiveness in the future. This may be particularly important in strategies for wider global use of conjugate vaccines in children, as well as use in adults and the elderly. Challenges such as pneumococcal serotype replacement make ongoing surveillance of carriage and invasive disease crucial and will have implications for conjugate reformulation and the development of alternative vaccines. New conjugate vaccines for other pathogens currently in clinical trials have the potential to reduce invasive bacterial disease further, particularly in resource-poor settings.

Pediatric complicated pneumonia and pneumococcal serotype replacement: trends in hospitalized children pre and post introduction of routine vaccination with Pneumococcal Conjugate Vaccine (PCV7)

Recent studies have described an increase in the incidence of complicated pneumonia in children, primarily caused by Streptococcus pneumoniae. The objective of this study was to determine if the incidence of complicated pneumonias in total and due to different pneumococcal serotypes has changed following the introduction of routine immunization with heptavalent pneumococcal conjugate vaccine (PCV7). A retrospective review of patients admitted to the Stollery Children's Hospital in Edmonton, Alberta with complicated pneumonia between July 1, 1997 and June 30, 2007 (5 years before and after the introduction of PCV7) was completed. There were 34 children in the pre- and 68 in the post-PCV7 era (14.31 and 19.91 per 10,000 discharges, respectively, p = 0.114). Patient characteristics were not significantly different, and pneumococcus was the most common organism isolated (pre: 21% (7/34); post: 26% (18/68), p = 0.515). In patients where serotype data was available, non-vaccine pneumococcal serotypes accounted for 67% (12/18) cases in the post-PVC7 era versus 14% (1/7) in the pre-PCV7 era (p = 0.031). The incidence of non-vaccine serotypes was 0.42 and 3.51 per 10,000 discharges in the pre- and post-PCV7 eras, respectively (p = 0.020). There has been a non-significant trend towards an increase in the incidence of complicated pneumonia following the introduction of PCV7. S. pneumoniae remains the predominant organism identified with non-vaccine serotypes now accounting for almost all cases. Although it is not clear if this increase is attributable to the use of PCV7, expanding pneumococcal serotype coverage has the potential to prevent complicated pneumonia.

Evidence that pneumococcal serotype replacement in Massachusetts following conjugate vaccination is now complete

Invasive pneumococcal disease (IPD) has been reduced in the US following conjugate vaccination (PCV7) targeting seven pneumococcal serotypes in 2000. However, increases in IPD due to other serotypes have been observed, in particular 19A. How much this “serotype replacement” will erode the benefits of vaccination and over what timescale is unknown. We used a population genetic approach to test first whether the selective impact of vaccination could be detected in a longitudinal carriage sample, and secondly how long it persisted for following introduction of vaccine in 2000. To detect the selective impact of the vaccine we compared the serotype diversity of samples from pneumococcal carriage in Massachusetts children collected in 2001, 2004, and 2007 with others collected in the pre-vaccine era in Massachusetts, the UK, and Finland. The 2004 sample was significantly ( p > 0.0001) more diverse than pre-vaccine samples, indicating the selective pressure of vaccination. The 2007 sample showed no significant difference in diversity from the pre-vaccine period and exhibited similar population structure, but with different serotypes. In 2007 the carriage frequency of 19A was similar to that of the most common serotype in pre-vaccine samples. We suggest that serotype replacement involving 19A may be complete in Massachusetts due to similarities in population structure to pre-vaccine samples. These results suggest that the replacement phenomenon occurs rapidly with high vaccine coverage and may allay concerns about future increases in disease due to 19A. For other serotypes, the future course of replacement disease remains to be determined.

MSP012 The origin of fluoroquiolone-resistant Escherichia coli in Intensive Care Units

Reports on the efficacy of pneumococcal conjugate vaccines (PCVs) have been received from many countries. However, in countries where the 7-valent PCV (PCV7) and 13-valent PCV (PCV13) were introduced, overall coverage of the serotypes by the vaccine gradually decreased due to pneumococcal serotype replacement. The aim of this study is to assess the distribution of pneumococcal serotypes and to also provide basic data on adult respiratory infection in Japan.We analyzed 1086 Streptococcus pneumoniae strains that had been isolated from respiratory tract infection specimens in adult patients from 2006 to 2014. Capsular typing was performed by the Quellung reaction and multiplex PCR.Among all 1086 strains, serotype 3 was the most common and was identified in 160 strains (14.7%), followed by serotypes 19F, 6B, 19A and 23F. From 2006–10 to 2012–14, the coverage rate of PCV7 tended to gradually decrease. Particularly, serotypes 6B and 19F of penicillin non-susceptible strains decreased. On the other hand, serotypes 19A and 15A of penicillin non-susceptible strains increased. However, coverage by PCV13 of penicillin-resistant S. pneumoniae (PRSP) (penicillin G minimum inhibitory concentration ≥2 μg/mL) remained high (88.7% [2006–10], 88.0% [2012–14]).In Japan, PCV13 vaccination of adults became available from June 2014. Our study demonstrated that most PRSP (88.0%) still remain covered by PCV13. At present, the introduction of PCV13 in adult clinical practice seems to be highly significant. However, there is a possibility that the distribution has been changing, and careful screening should be continued in the future.