Increase in incidence of invasive pneumococcal disease caused by serotype 3 in children eight years after the introduction of the pneumococcal conjugate vaccine in Hong Kong

Streptococcus pneumoniae serotype 3 population structure in the era of conjugate vaccines, 2001-2018

Background. Despite use of highly effective conjugate vaccines, invasive pneumococcal disease (IPD) remains a leading cause of morbidity and mortality and disproportionately affects Indigenous populations. Although included in the 13-valent pneumococcal conjugate vaccine (PCV13), which was introduced in 2010, serotype 3 continues to cause disease among Indigenous communities in the Southwest USA. In the Navajo Nation, serotype 3 IPD incidence increased among adults (3.8/100 000 in 2001-2009 and 6.2/100 000 in 2011-2019); in children the disease persisted although the rates dropped from 5.8/100 000 to 2.3/100 000.Methods. We analysed the genomic epidemiology of serotype 3 isolates collected from 129 adults and 63 children with pneumococcal carriage (n=61) or IPD (n=131) from 2001 to 2018 of the Navajo Nation. Using whole-genome sequencing data, we determined clade membership and assessed changes in serotype 3 population structure over time.Results. The serotype 3 population structure was characterized by three dominant subpopulations: clade II (n=90, 46.9 %) and clade Iα (n=59, 30.7 %), which fall into Clonal Complex (CC) 180, and a non-CC180 clade (n=43, 22.4 %). The proportion of clade II-associated IPD cases increased significantly from 2001 to 2010 to 2011-2018 among adults (23.1-71.8 %; P<0.001) but not in children (27.3-33.3 %; P=0.84). Over the same period, the proportion of clade II-associated carriage increased; this was statistically significant among children (23.3-52.6 %; P=0.04) but not adults (0-50.0 %, P=0.08).Conclusions. In this setting with persistent serotype 3 IPD and carriage, clade II has increased since 2010. Genomic changes may be contributing to the observed trends in serotype 3 carriage and disease over time.

The impact of the introduction of ten- or thirteen-valent pneumococcal conjugate vaccines on antimicrobial-resistant pneumococcal disease and carriage: A systematic literature review

Background

A systematic review in 2019 found reductions in antimicrobial resistance (AMR) of pneumococcal vaccine serotypes following pneumococcal conjugate vaccine (PCV) introduction. However, few low- or middle-income countries were included as not many had introduced higher valent PCVs (PCV10 or PCV13). The aim of our review is to describe AMR rates in these samples following the introduction of PCV10 or PCV13.

Methods

We conducted a systematic literature review of published papers that compared AMR for invasive pneumococcal disease (IPD), otitis media (OM) and nasopharyngeal carriage (NPC) samples following introduction of PCV10 or PCV13 to the pre-PCV period. Included studies published from July 2017 to August 2020 had a post-licensure observational study design and reported on our defined outcomes: IPD, OM, NPC and other (sputum or mixed invasive and non-invasive pneumococcal) isolates from people of all ages. Rates of AMR in the pre- and post-period were extracted.

Results

Data were extracted from 31 studies. Among IPD isolates, penicillin AMR rates following PCV10 or PCV13 introduction declined in 32% (n = 9/29) of included studies, increased in 34% (n = 10/29) and showed no change in 34% (n = 10/29). Cephalosporins AMR declined in 32% (n = 6/19) of studies, increased in 21% (n = 4/19) and showed no change in 47% (n = 9/19). Macrolides AMR declined in 33% (n = 4/12) of studies, increased in 50% (n = 6/12), and showed no change in 17% (n = 2/12). AMR to other antibiotics (including multidrug resistance) declined in 23% (n = 9/39) of studies, increased in 41% (n = 16/39) and showed no change in AMR in 36% (n = 14/39). There were no obvious differences between AMR; in setting which used PCV10 vs PCV13, according to time since PCV introduction or by World Bank income status of the respective country. The only study including OM isolates found no change in penicillin resistance. There were few studies on AMR in NPC (four studies), OM (one study) or other isolates (five studies). The results followed similar patterns to IPD isolates.

Conclusions

We observed considerable heterogeneity in the findings between and within studies, e.g. no evidence of reduction in amoxicillin AMR with an increase in macrolides AMR. Reasons for such diverse findings include the period covered by different studies and variation in other pressures towards AMR.

Changes in Etiology and Clinical Outcomes of Pleural empyema during the COVID-19 Pandemic

Healthcare-seeking behavior changed during the COVID-19 pandemic and might alter the epidemiology of pleural empyema. In this study, the incidence, etiology and outcomes of patients admitted for pleural empyema in Hong Kong in the pre-COVID-19 (January 2015-December 2019) and post-COVID-19 (January 2020-June 2022) periods were compared. Overall, Streptococcus pneumoniae was the predominant organism in <18-year-old patients, while Streptococcus anginosus, anaerobes and polymicrobial infections were more frequent in adults. In the post-COVID-19 period, a marked decline in the incidence of pleural empyema in children was observed (pre-COVID-19, 18.4 ± 4.8 vs. post-COVID-19, 2.0 ± 2.9 cases per year, p = 0.036), while the incidence in adults remained similar (pre-COVID-19, 189.0 ± 17.2 vs. post-COVID-19, 198.4 ± 5.0 cases per year; p = 0.23). In the post-COVID-19 period, polymicrobial etiology increased (OR 11.37, p < 0.0001), while S. pneumoniae etiology decreased (OR 0.073, p < 0.001). In multivariate analysis, clinical outcomes (length of stay, ICU admission, use of intrapleural fibrinolytic therapy, surgical intervention, death) were not significantly different in pre- and post-COVID-19 periods. In conclusion, an increase in polymicrobial pleural empyema was observed during the pandemic. We postulate that this is related to the delayed presentation of pneumonia to hospitals.

Acute Kidney Injury and Hemolytic Uremic Syndrome in Severe Pneumococcal Pneumonia—A Retrospective Analysis in Pediatric Intensive Care Unit

Objectives: This study aimed to evaluate the prevalence of acute kidney injury (AKI) and hemolytic uremic syndrome (HUS) in severe pediatric pneumonia due to Streptococcus pneumoniae and to identify factors associated with AKI and HUS in these patients.

Methods: We retrospectively analyzed pediatric patients who were admitted to our pediatric intensive care unit due to severe pneumococcal pneumonia between 2013 and 2019.

Results: Forty-two patients with a median age of 4.3 years were included. Among these patients, 14 (33.3%) developed AKI, including seven (16.7%) stage 1, two (4.8%) stage 2, and five (11.9%) stage 3 AKI. Features of HUS were present in all of the patients with stage 3 AKI, and four required renal replacement therapy (RRT), with a median duration of 10.5 days (range 3 to 16 days). All patients with HUS required mechanical ventilation and inotropic supports. Patients with lower leukocyte and platelet counts, serum sodium and bicarbonate levels, positive urine dipstick (heme or protein ≥ 2 + ), and presence of bacteremia were associated with stage 2 and 3 AKI.

Conclusions: Pediatricians should be aware of the relatively high prevalence of kidney involvement in severe pneumococcal pneumonia, with one-third having AKI and 11.9% developing HUS. Majority (80%) of HUS patients required RRT. Positive urine dipstick, serum sodium, and bicarbonate at presentation, which can be measured in point-of-care tests, may potentially be useful as quick tests to stratify the risks of moderate-to-severe AKI.

Health and economic burden associated with 15-valent pneumococcal conjugate vaccine serotypes in Korea and Hong Kong

Use of pneumococcal conjugate vaccines (PCVs) has greatly reduced the incidence of invasive pneumococcal disease (IPD). V114 (VAXNEUVANCE™, Merck Sharp & Dohme Corp. a subsidiary of Merck & Co. Inc. Kenilworth, NJ, USA) is a 15-valent PCV currently approved in adults in the United States, containing the 13 serotypes in licensed PCV13 and 2 additional serotypes (22F and 33F) which are important contributors to residual pneumococcal disease. This study quantified the health and economic burden of IPD attributable to V114 serotypes in hypothetical birth cohorts from Korea and Hong Kong. A Markov model was used to estimate the case numbers and costs of IPD in unvaccinated birth cohorts over 20 years. The model was applied to 3 scenarios in Korea (pre-PCV7, pre-PCV13, and post-PCV13) and to 2 scenarios in Hong Kong (pre-PCV7 and post-PCV13). For Korea, the model predicted 62, 26, and 8 IPD cases attributable to V114 serotypes in the pre-PCV7, pre-PCV13, and post-PCV13 scenarios, respectively. Costs of V114-type IPD fell from $1.691 million pre-PCV7 to $.212 million post-PCV13. For Hong Kong, the model estimated 62 V114-associated IPD cases in the pre-PCV7 scenario and 46 in the post-PCV13 scenario. Costs attributed to all V114 serotypes were $2.322 million and $1.726 million in the pre-PCV7 and post-PCV13 periods, respectively. Vaccine-type serotypes are predicted to cause continuing morbidity and cost in Korea (19A) and Hong Kong (3 and 19A). New pediatric pneumococcal vaccines must continue to protect against serotypes in licensed vaccines to maintain disease reduction, while extending coverage to non-vaccine serotypes.

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

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

Streptococcus pneumoniae vaccination strategies and its expected impact on penicillin non-susceptibility in children under the age of five: Let's recap!

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The efficacy of PCVs currently used in children under 5 years of age is threatened by the emergence of invasive and resistant non-vaccine serotypes worldwide.

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Resistant NVT strains are emerging in IPD in children < 5 years mainly serotypes 24F, 15A, 11A and 33F along with serotype 19A in PCV-10 settings.

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Continuous surveillance is necessary in IPD in children under five to monitor the long-term effect of PCV-10 and PCV-13 on penicillin resistance trends.

The impact of pneumococcal conjugate vaccines (PCVs) on invasive pneumococcal disease (IPD) burden has been extensively studied in children aged<5 years; however, a pooled estimation of the effect of PCVs on penicillin non-susceptible pneumococci (PNSP) has not yet been performed. We aimed to identify whether the introduction of PCV-10 and PCV-13 had led to the decrease of the overall PNSP rate in children < 5 years. We conducted a systematic review of published surveillance studies reporting the rate of PNSP rates in children < 5 in countries where PCV10/13 were introduced. The overall observed trend onwards the introduction of PCV-10 and PCV-13 is a decrease in PNSP among children < 5 years in surveillance sites located in PCV-13 countries. We identified an increase of PNSP rates (serotype 19A) in PCV-10 settings. Resistant NVT strains are emerging in IPD in children < 5 years mainly serotypes 24F, 15A, 11A and 33F along with serotype 19A in PCV-10 settings. Continuous surveillance is necessary in IPD in children under five to monitor the long-term effect of PCV-10 and PCV-13 on penicillin resistance trends.

Antibiotic Resistance and Molecular Biological Characteristics of Non-13-Valent-Pneumococcal Conjugate Vaccine Serogroup 15 Streptococcus pneumoniae Isolated From Children in China

Background: The isolation rate of serogroup 15 Streptococcus pneumoniae has been increasing since developing countries began administering the 13-valent pneumococcal conjugate vaccine.

Methods: We detected the antibiotic resistance and molecular characteristics of 126 serogroup 15 S. pneumoniae strains isolated from children in China. Serotypes were determined via the Quellung reaction. Antibiotic resistance was tested using the E-test or disc diffusion method. Sequence types were assigned via multilocus sequence typing. Data were analyzed using WHONET 5.6 software.

Results: The frequencies of S. pneumoniae serotypes 15A, 15B, 15C, and 15F were 29.37, 40.48, 28.57, and 1.59%, respectively. Continuous-monitoring data from Beijing showed that the annual isolation rates of serogroup 15 S. pneumoniae were 7.64, 7.17, 2.58, 4.35, 3.85, 7.41, and 10.53%, respectively, from 2013 to 2019. All 126 serogroup 15 strains were susceptible to vancomycin and ceftriaxone. The non-susceptibility rate to penicillin was 78.57%. All strains were resistant to erythromycin with high minimum inhibitory concentrations (MICs). The multidrug resistance rate was 78.57%. The most common clonal complexes were CC3397, CC6011, CC10088, CC9785, and ST8589.

Conclusion: Serogroup 15 S. pneumoniae is common among children in China, and these strains should be continuously monitored.

Genomic investigation of a Streptococcus pneumoniae serotype 24F strain causing meningoencephalitis in Hong Kong

Pneumococcal conjugate vaccines (PCVs) successfully decreased the incidence of invasive pneumococcal disease in children. However, many countries have reported serotype replacement and a rebound in diseases from non-vaccine serotypes. Here, we report the genomic investigation of a Streptococcus pneumoniae strain M215 that caused severe meningoencephalitis in an infant in 2019. The strain was assigned to serotype 24F using the bioinformatic pipeline SeroBA and pneumococcal type specific anti-sera. The strain was resistant to cotrimoxazole from mutations in both folA and folP genes. It was susceptible to penicillin and other non-β-lactam antibiotics. Phylogenetically, it belongs to Global Pneumococcal Sequence Cluster (GPSC) 6 and multi-locus sequence type 162. A total of 38 virulence genes were detected in the genome of M215. Upon comparison of the profile of virulence genes, GPSC6 but not non-GPSC6 strains of serotype 24F and related serotypes were found to possess the major virulence determinant, pilus islet-1, comprising genes encoding sortases (srtB, srtC, srtD), pilus proteins (rrgA, rrgB and rrgC) and one transcriptional regulator (rlrA), which was previously described to be characteristic feature of international clones in the pre-PCV era. In our locality, this represented the first detection of serotype 24F and GPSC6/ST162 causing serious pneumococcal disease. The emergence of the non-vaccine serotype 24F GPSC6/ST162 lineage with molecular feature of high virulence is concerning and emphasizes the need for full characterization of strains causing severe disease.

Epidemiology of non-vaccine serotypes of Streptococcus pneumoniae before and after universal administration of pneumococcal conjugate vaccines

The universal administration of pneumococcal conjugate vaccines (PCVs) had been demonstrated as an effective way to prevent Streptococcus pneumoniae infection. However, the immunity induced by PCVs protected against the infections caused by vaccine serotypes, which were usually more frequent than non-vaccine serotypes (NVTs). The prevalence and pathogenicity of NVTs after universal vaccination have caused widespread concern. We reviewed the epidemiology of non-PCV13 S. pneumoniae before and after PCV13 introduction, and explored the potential reasons for the spread of NVTs. Emerging and spreading NVTs can be regarded as the focus for future serotype epidemiological survey and vaccine optimization.AbbreviationsIPD: invasive pneumococcal disease PCV: pneumococcal conjugate vaccines VT: vaccine serotypeNVT: non-vaccine serotype.

Invasive pneumococcal disease, pneumococcal pneumonia and all-cause pneumonia in Hong Kong during the COVID-19 pandemic compared with the preceding 5 years: a retrospective observational study

OBJECTIVES

To compare the incidence and severity of invasive pneumococcal diseases (IPDs), pneumococcal pneumonia and all-cause pneumonia during the COVID-19 pandemic period with universal masking and social distancing with that of previous 5 years.

DESIGN

Retrospective observational study on incidence of IPDs, pneumococcal pneumonia and all-cause pneumonia between January 2015-December 2019 and March 2020-March 2021. January-February 2020 was excluded from analysis as it was treated as a transitional period between normal time and pandemic.

SETTING

Episode-based data by retrieval of hospitalisation records from the Hospital Authority's territory-wide electronic medical record database in Hong Kong.

PARTICIPANTS

Hospitalised patients with IPD (n=742), pneumococcal pneumonia (n=2163) and all-cause pneumonia (including COVID-19 pneumonia, n=453 999) aged 18 years or above. Control diagnoses were included to assess confounding from health-seeking behaviours.

PRIMARY AND SECONDARY OUTCOMES

Primary outcome is the incidence of diseases between two periods. Secondary outcomes include disease severity surrogated by length of stay and mortality.

RESULTS

Monthly average number of IPD, pneumococcal pneumonia and all-cause pneumonia hospitalisation significantly decreased by 88.9% (95% CI 79.8% to 98.0%, p<0.0005), 72.5% (95% CI 65.9% to 79.1%, p<0.0005) and 17.5% (95% CI 16.8% to 18.2%, p<0.0005), respectively. Changes in trend from January 2015-December 2019 to March 2020-March 2021 were -70% (95% CI -87% to -35%, p=0.0025), -43% (95% CI -59% to -19%, p=0.0014) and -11% (95% CI -13% to -10%, p<0.0005), respectively. Length of stay for IPD and pneumococcal pneumonia episodes were insignificantly different in the two periods. No reductions in hospitalisations for control diagnoses were observed.

CONCLUSIONS

Incidence of IPD, pneumococcal pneumonia and all-cause pneumonia decreased during the COVID-19 pandemic. This was observed with universal masking and social distancing. We postulated this is related to reduced transmission of respiratory viruses and bacteria.

Genotypic and phenotypic characteristics of Streptococcus pneumoniae from community-acquired pneumonia patients and healthy asymptomatic participants in Sichuan province, China

Background

Streptococcus pneumoniae (S. pneumoniae) is the common cause of community-acquired pneumonia (CAP) and is also found in the upper respiratory tract of healthy people. Hence, the study aimed to compare the serotypes, virulence/pili genes, and antibiotic susceptibility of S. pneumoniae from healthy asymptomatic participants and CAP patients.

Methods

Streptococcus pneumoniae were retrospectively collected from health asymptomatic participants and CAP patients in Sichuan, China. The serotypes were tested by multiplex polymerase chain reaction (PCR) or Quellung reaction. Antibiotic susceptibility testing was performed using the broth microdilution method. The molecular epidemiology of S. pneumoniae was analyzed by multilocus sequence typing (MLST). Additionally, the presence of virulence/pili genes were detected using PCR.

Results

A total of 83 pneumococcal isolates were collected in the current study. Of these, 52 and 31 isolates were from healthy asymptomatic participants and CAP patients, respectively. Most of S. pneumoniae were resistant to erythromycin (ERY), clindamycin (CLI), tetracycline (TET) and trimethoprim-sulfamethoxazole (SXT). 90.4% isolates were classified as multidrug resistant (MDR). The predominant serotypes were 3, 19F and 19A in the CAP carriers, whereas 3, 6 and 19F were the main serotypes among the asymptomatic carriers. The overall coverage rates of pneumococcal conjugate vaccine (PCV) 10 and PCV13 serotypes were 34.9% and 66.3%, respectively. The predominant sequence types (STs) were ST271, ST320, and ST3397. There were significant differences in some resistance and virulence characteristics between CAP patients and asymptomatic carriers. Additionally, clonal complex (CC) 271 strains had higher percentage in resistance to cefuroxime (CXM) and cefotaxime (CEF), meropenem (MER) and cefepime (CFP), which mainly carried the rlrA and sipA genes.

Conclusions

High coverage rate of PCV13 and high prevalence of MDR indicated the necessity to expand immunization with PCV13 and rationally use the antibiotics in Sichuan, China. Importantly, long-term surveillance should be conducted to assess effectiveness brought by vaccines. Our findings may supply new guidance for developing new pneumococcal vaccines.

Global genomic pathogen surveillance to inform vaccine strategies: a decade-long expedition in pneumococcal genomics

Vaccines are powerful agents in infectious disease prevention but often designed to protect against some strains that are most likely to spread and cause diseases. Most vaccines do not succeed in eradicating the pathogen and thus allow the potential emergence of vaccine evading strains. As with most evolutionary processes, being able to capture all variations across the entire genome gives us the best chance of monitoring and understanding the processes of vaccine evasion. Genomics is being widely adopted as the optimum approach for pathogen surveillance with the potential for early and precise identification of high-risk strains. Given sufficient longitudinal data, genomics also has the potential to forecast the emergence of such strains enabling immediate or pre-emptive intervention. In this review, we consider the strengths and challenges for pathogen genomic surveillance using the experience of the Global Pneumococcal Sequencing (GPS) project as an early example. We highlight the multifaceted nature of genome data and recent advances in genome-based tools to extract useful information relevant to inform vaccine strategies and treatment options. We conclude with future perspectives for genomic pathogen surveillance.

Substantial decline in invasive pneumococcal disease (IPD) during COVID-19 pandemic in Hong Kong

Compared with other countries, a more substantial decrease in the incidence of invasive pneumococcal disease was observed in Hong Kong, which is most likely attributable to the proactive mass adoption of face masks by the public. Human behavioral changes, particularly mask wearing, should be considered as an additional preventive strategy against invasive pneumococcal disease.

Serotype distribution and clinical characteristics associated with streptococcus pneumoniae among Chinese children and adults with invasive pneumococcal disease: a multicenter observational study

Few studies in China focused on serotypes of Streptococcus pneumoniae in patients with invasive pneumococcal disease (IPD). We aimed at investigating the serotype distribution for IPD-causing S. pneumoniae and vaccine coverage among Chinese children and adults. This was a multicenter, observational study to collect S. pneumoniae isolates from normal sterile sites and IPD-related clinical information among children and adults. Serotyping was performed by a Capsule-Quellung reaction test using type-specific antisera. The study collected a total of 300 eligible isolates (pediatric = 148, adult = 152) were serotyped in a central laboratory. The most prevalent serotypes were 19A (20.9%) and 23 F (20.3%) in the pediatric group; 3 (21.7%) and 19 F (11.8%) in the adult group. PCV10 had low-to-moderate serotype coverage rates for children (60.8%) and adults (34.2%). PCV13 and PPV23 had high coverage rates for children (89.9%, 93.2%) and adults (70.4%, 82.9%), respectively, Investigational PCVs including PCV15 and PCV20 had high estimated coverage rates in children (89.9%, 93.9%). The study identified 269 subjects with IPD reported as the primary diagnosis in the medical records. Sepsis (48/136, 35.3%) and pneumonia (48/133, 36.1%) had the highest occurrence in the pediatric and adult groups, respectively. Study findings showed that non-PCV7 S. pneumoniae 19A and 3 were the most prevalent serotypes in Chinese children and adults, respectively. High-valent vaccines had similar coverage rates and may have a greater potential in preventing IPD.

Incidence of invasive pneumococcal disease after introduction of the 13-valent conjugate pneumococcal vaccine in British Columbia: A retrospective cohort study

BACKGROUND

A significant reduction in invasive pneumococcal disease (IPD) has been reported, across all ages, following the implementation of 7-valent conjugate pneumococcal vaccine (PCV7) globally, as part of infant immunization programs. We explored the additional impact of PCV13 on IPD over a 14-year period.

METHODS

Using provincial laboratory surveillance and hospitalization data (N = 5791), we calculated the annual incidence of IPD following the implementation of PCV13 vaccine. Poisson regression was used to evaluate changes in the overall incidence of IPD, and serotype-specific IPD between PCV7 (2004-10) and PCV13 (2011-2015) eras.

RESULTS

Overall, IPD rates have seen a modest decline in the PCV13 compared to the PCV7 era (IRR 0.84; 95% CI: 0.79-0.89); this was seen in children ≤2 years of age, and the majority of the adult cohort. Rates of vaccine-type IPD (PCV7 and PCV13) also decreased in the PCV13 era. In contrast, IPD incidence related to non-PCV13 (IRR: 1.56; 95%CI:1.43-1.72) and non-vaccine serotypes (IRR: 2.12; 95%CI:1.84-2.45) increased in the PCV13 era compared to the PCV7 era.

CONCLUSIONS

A modest reduction in IPD from the PCV13 vaccine was observed, with gains limited to the immunized cohort and adults. However, a significant increase in non-vaccine serotypes emphasizes the need for continued surveillance.

Nationwide Trends of Invasive Pneumococcal Disease in Spain From 2009 Through 2019 in Children and Adults During the Pneumococcal Conjugate Vaccine Era

Background

Introduction of pneumococcal conjugate vaccines (PCVs) has reduced the disease caused by vaccine serotypes in children, providing herd protection to adults. However, the emergence of nonvaccine serotypes is of great concern worldwide.

Methods

This study includes national laboratory data from invasive pneumococcal disease (IPD) cases that affected pediatric and adult populations during 2009–2019. The impact of implementing different vaccine strategies for immunocompetent adults by comparing Spanish regions that used the 13-valent PCV (PCV13) vs regions that used the 23-valent pneumococcal polysaccharide vaccine (PPV23) was also analyzed for 2017−2019.

Results

The overall reductions in IPD cases by PCV13 serotypes in children and adults were 88% and 59%, respectively, during 2009–2019, with a constant increase in serotype 8 in adults since 2015. IPD cases by additional serotypes covered by PPV23 increased from 20% in 2009 to 52% in 2019. In children, serotype 24F was the most frequent in 2019, whereas serotypes 3 and 8 accounted for 36% of IPD cases in adults. Introduction of PCV13 or PPV23 in the adult calendar of certain Spanish regions reduced the IPD cases by PCV13 serotypes by up to 25% and 11%, respectively, showing a decrease of serotype 3 when PCV13 was used.

Conclusions

Use of PCV13 in children has affected the epidemiology, reducing the burden of IPD in children but also in adults by herd protection; however, the increase in serotype 8 in adults is worrisome. Vaccination with PCV13 in adults seems to control IPD cases by PCV13 serotypes including serotype 3.

Characteristics of Serotype 3 Invasive Pneumococcal Disease before and after Universal Childhood Immunization with PCV13 in Massachusetts

BACKGROUND

Although a substantial decline in vaccine-serotype invasive pneumococcal disease (IPD) incidence was observed following the introduction of pneumococcal conjugate vaccines (PCV), the estimated range of thirteen-valent conjugate vaccine (PCV13) effectiveness for serotype 3 disease is wide and includes zero. We assessed the impact of PCV13 on serotype 3 IPD incidence and disease characteristics in Massachusetts' children.

METHODS

Serotype 3 IPD cases in children <18 years old were identified via enhanced passive surveillance system in Massachusetts. We compared incidence rates and characteristics of IPD cases before and after PCV13.

RESULTS

A total of 47 serotype 3 IPD cases were identified from 2002 to 2017; incidence of serotype 3 IPD in the years following PCV13 was 0.19 per 100,000 children compared to 0.21 before PCV 13, incidence rate ratio (IRR) = 0.86 (95% CI 0.47-1.57). The majority (78%) of post-PCV13 serotype 3 IPD cases occurred among fully vaccinated children. Age distribution, clinical syndrome and presence of comorbidities among serotype 3 IPD cases were similar before and after PCV13 introduction. There was no association between the date of the last PCV13 dose and time to IPD to suggest waning of immunity.

CONCLUSIONS

seven years following PCV 13 we found no significant changes in serotype 3 IPD incidence or disease characteristics in children in Massachusetts.

The shifting epidemiology and serotype distribution of invasive pneumococcal disease in Ontario, Canada, 2007-2017

Background

Ontario, Canada introduced a publicly-funded 13-valent pneumococcal conjugate vaccine (PCV13) for infants in 2010, replacing the 10-valent (PCV10, 2009–2010) and the 7-valent (PCV7, 2005–2009) conjugate vaccine programs; a 23-valent pneumococcal polysaccharide vaccine (PPV23) has been available for older adults since 1996. We examined the epidemiology and serotype distribution of invasive pneumococcal disease (IPD) in Ontario in the context of provincial immunization programs.

Methods

We included confirmed IPD cases reported in Ontario between 2007 and 2017. We grouped serotypes according to Ontario’s current immunization program (PCV13, PPV23, and non-vaccine-preventable) and calculated incidence rates (per 100,000 population) using population data.

Results

Between 2007 and 2017, annual incidence of IPD in Ontario ranged between 7.3 and 9.7/100,000 per year. Measures of illness severity were high throughout the period of surveillance. After PCV13 program implementation in 2010, incidence due to PCV13 serotypes decreased significantly across all age groups, with the greatest reductions in children <5 years and adults ≥65 years. Conversely, incidence due to PPV23 unique serotypes increased significantly between 2007 and 2017, with the greatest increases observed in adults 50–64 years (1.4 to 3.5/100,000) and ≥65 years (2.3 to 7.2/100,000). Similar increases were observed in incidence due to non-vaccine-preventable serotypes among all age groups, except infants <1 year. Within specific serotypes, incidence due to serotypes 3 (0.42 to 0.98/100,000) and 22F (0.31 to 0.72/100,000) increased significantly between 2007 and 2017, while incidence due to serotypes 19A and 7F decreased significantly during the PCV13 period (2010–2017).

Conclusions

Eight years after PCV13 implementation in Ontario, our data suggest both direct and indirect effects on serotype-specific incidence in young children and older adults. However, overall provincial rates have remained unchanged, and IPD continues to be a severe burden on the population. The rising incidence of IPD due to PPV23 unique and non-vaccine-preventable serotypes, and the growing burden of serotypes 3 and 22F, require further study.