•The post-PCV invasive disease potential of 25 pneumococcal serotypes was estimated.•The invasive disease potential of non-vaccine types, except 12F, are lower than 19A.•Age and disease presentation ...influence the invasive disease potential of serotypes.•Knowledge of invasive disease potential is valuable to assess and design vaccines.•Due to the diversity, surveillance of serotypes in carriage and IPD is critical.
Burden of pneumococcal disease depends on the prevalence and invasive disease potential of serotypes. We aimed to estimate the invasive disease potential of serotypes in children under 5 years of age by combining data from different settings with routine immunisation with pneumococcal conjugate vaccines (PCV).
We conducted a systematic review, supplemented by unpublished data, to identify data on the frequency of pneumococcal serotypes in carriage and invasive pneumococcal disease (IPD). We estimated the invasive disease potential of serotypes as the ratio of IPD in relation to carriage (odds ratio and 95%CI) compared with 19A (reference serotype) by meta-analysis. We report results based on a random effects model for children aged 0–23, 24–29, and 0–59 months and by invasive clinical syndromes.
In comparison with 19A, serotypes 1, 7F, and 12F had a significantly higher invasive disease potential in children aged 0–23 and 0–59 months for all IPD and clinical syndromes (OR > 5). Several non-vaccine types (NVTs) (6C, 15A, 15BC, 16F, 23B, in these two age groups) had a lower invasive disease potential than 19A (OR 0.1–0.3). NVTs 8, 12F, 24F, and 33F were at the upper end of the invasiveness spectrum.
There is substantial variation among pneumococcal serotypes in their potential to cause IPD and disease presentation, which is influenced by age and time after PCV introduction. Surveillance of IPD and carriage is critical to understand the expected effectiveness of current PCVs (in the longer term) and guide the development of future vaccines.
•Pneumococcal conjugate vaccines have modestly reduced circulating vaccine serotypes in Soweto, South Africa.•There is a residual of vaccine serotypes.•Colonization by vaccine-serotype 19F remains ...high.•Co-colonization is higher in our setting than observed elsewhere.
Pneumococcal conjugate vaccines (PCVs) reduce pneumococcal-associated disease by reducing vaccine-serotype (VT) acquisition in vaccinated children, thereby interrupting VT transmission. The 7-valent-PCV was introduced in the South African immunization program in 2009 (13-valent-PCV since 2011) using a 2+1 schedule (at 6, 14, and 40 weeks of age). We aimed to evaluate temporal changes in VT and non-vaccine-serotype (NVT) colonization after 9 years of childhood PCV immunization in South Africa.
Nasopharyngeal swabs were collected from healthy children <60-month-old (n = 571) in 2018 (period-2) and compared with samples (n = 1135) collected during early PCV7-introduction (period-1, 2010-11) in an urban low-income setting (Soweto). Pneumococci were tested for using a multiplex quantitative-polymerase chain reaction serotyping reaction-set.
Overall pneumococcal colonization in period-2 (49.4%; 282/571) was 27.5% lower than period-1 (68.1%; 773/1135; adjusted odds ratio aOR: 0.66; 95% confidence interval CI: 0.54-0.88). Colonization by VT was reduced by 54.5% in period-2 (18.6%; 106/571) compared with period-1 (40.9%; 465/1135; aOR: 0.41; 95% CI: 0.3-0.56). Nevertheless, serotype 19F carriage prevalence was higher (8.1%; 46/571) in period-2 compared with period-1 (6.6%; 75/1135; aOR: 2.0; 95% CI: 1.09-3.56). NVT colonization prevalence was similar in period-2 and period-1 (37.8%; 216/571 and 42.4%; 481/1135).
There remains a high residual prevalence of VT, particularly 19F, colonization nine years post-introduction of PCV in the South African childhood immunization program.
Pneumococcal conjugate vaccines have reduced the incidence of invasive pneumococcal disease, caused by vaccine serotypes, but non-vaccine-serotypes remain a concern. We used whole genome sequencing ...to study pneumococcal serotype, antibiotic resistance and invasiveness, in the context of genetic background.
Our dataset of 13,454 genomes, combined with four published genomic datasets, represented Africa (40%), Asia (25%), Europe (19%), North America (12%), and South America (5%). These 20,027 pneumococcal genomes were clustered into lineages using PopPUNK, and named Global Pneumococcal Sequence Clusters (GPSCs). From our dataset, we additionally derived serotype and sequence type, and predicted antibiotic sensitivity. We then measured invasiveness using odds ratios that relating prevalence in invasive pneumococcal disease to carriage.
The combined collections (n = 20,027) were clustered into 621 GPSCs. Thirty-five GPSCs observed in our dataset were represented by >100 isolates, and subsequently classed as dominant-GPSCs. In 22/35 (63%) of dominant-GPSCs both non-vaccine serotypes and vaccine serotypes were observed in the years up until, and including, the first year of pneumococcal conjugate vaccine introduction.
Penicillin and multidrug resistance were higher (p < .05) in a subset dominant-GPSCs (14/35, 9/35 respectively), and resistance to an increasing number of antibiotic classes was associated with increased recombination (R2 = 0.27 p < .0001). In 28/35 dominant-GPSCs, the country of isolation was a significant predictor (p < .05) of its antibiogram (mean misclassification error 0.28, SD ± 0.13).
We detected increased invasiveness of six genetic backgrounds, when compared to other genetic backgrounds expressing the same serotype. Up to 1.6-fold changes in invasiveness odds ratio were observed.
We define GPSCs that can be assigned to any pneumococcal genomic dataset, to aid international comparisons. Existing non-vaccine-serotypes in most GPSCs preclude the removal of these lineages by pneumococcal conjugate vaccines; leaving potential for serotype replacement. A subset of GPSCs have increased resistance, and/or serotype-independent invasiveness.
Background. The public health impact of rotavirus vaccination in African settings with a high human immunodeficiency virus (HIV) infection prevalence is yet to be established. We evaluated trends in ...all-cause diarrheal hospitalizations in Soweto, Johannesburg, before and after the introduction of rotavirus vaccine into South Africa's national immunization program in August 2009. Methods. Hospitalizations in children <5 years of age with a diagnosis of diarrhea, defined by International Classification of Diseases, Tenth Revision codes A00–A05, A06.0–A06.3, A06.9, A07.0–A07.2, A07.9, and A08–A09, were identified at the Chris Hani Baragwanath Academic Hospital from 1 January 2006 to 31 December 2014. The median annual prevaccine (2006–2008) hospitalization incidence was compared to that of the vaccine era (2010–2014), and stratified by age group and HIV infection status. Results. Incidence reductions (per 1000 population) were greatest in children aged <12 months: 54.4 in the prevaccine era vs 30.0, 23.6, 20.0, 18.8, and 18.9 in the postvaccine years 2010–2014, respectively (a 44.9%–65.4% reduction). Lower incidence reductions (39.8%–49.4%) were observed among children aged 12–24 months from the second year post–vaccine introduction onward. Reductions were observed in both HIV-infected and HIV-uninfected children. There was a change in the seasonal pattern of diarrheal hospitalizations post–vaccine introduction, with flattening of the autumn–winter peaks seen in the prevaccine years. Conclusions. An accelerated and sustained decline in all-cause diarrheal hospitalizations, temporally associated with rotavirus vaccine introduction, was observed in children <2 years of age. However, the impact of other interventions such as improved sanitation and changes in HIV management cannot be discounted.
We evaluated pneumococcal colonization in children and adults between the time of 7-valent pneumococcal conjugate vaccine (PCV) introduction in the immunization program in 2009 to two years after ...transitioning to PCV13 in 2011.
Community-based carriage surveillance was undertaken between May-November 2013 (Period-3), with similar surveys in 2009 (Period-1) and 2011 (Period-2). Households with children below two years had a similar probability of being sampled in all surveys. Nasopharyngeal swabs were processed using standard methods and serotyped by Quellung.
In children>9-59 months old, overall pneumococcal colonization prevalence declined from 81.8% in Period-1 to 65.0% in Period-3 (p<0.001). Reductions of 70% (41.2% vs. 13.6%) in PCV7-serotypes colonization and 66% (15.3% vs. 4.4%) for the six additional PCV13-serotypes (PCV13-add6VT) were observed. There was, however, high residual colonization by PCV7-serotypes 19F (14.9% vs. 6.3%) and 23F (8.5% vs. 4.1%), despite reduction of 57% and 52%, respectively. Among individuals>12 years of age, there was 61% reduction in PCV7-serotype colonization (3.1% vs. 1.3%) and 75% decrease for PCV13-add6VT (2.1% vs. 0.6%) between Period-1 and Period-3.
The residual prevalence of serotypes 19F and 23F, four years after introducing PCV in the South Africa, suggests ongoing community transmission and transient vaccine effects.
Background. We investigated the impact of infant pneumococcal conjugate vaccine (PCV) immunization on pneumococcal colonization among human immunodeficiency virus (HIV)-infected and HIV-uninfected ...motherchild pairs. Methods. Pneumococcal colonization was assessed in May 2010-February 2011 (period 1; 7-valent PCV era) and May 2012-April 2013 (period 2; 13-valent PCV era). Standard microbiological methods were used for pneumococcus isolation and serotyping. Results. In children 0-12 years, PCV13-serotype colonization decreased from period 1 to period 2 among HIVuninfected (adjusted odds ratio OR, 0.32; 95% confidence interval CI, .25-.40) and HIV-infected children (adjusted OR, 0.37; 95% CI, .28-.49), while there was an increase in nonvaccine serotype colonization. Decreases in PCV13-serotype colonization were observed in HIV-uninfected women (adjusted OR, 0.44; 95% CI, .23-.81), with a similar trend in HIV-infected women. HIV-infected compared to -uninfected women had higher prevalence of overall (20.5% vs 9.7% in period 1; 13.8% vs 9.7% in period 2) and PCV 13-serotype colonization (8.7% vs 5.4% in period 1; 4.8% vs 2.0% in period 2), P<.04 for all observations. Conclusions. Targeted PCV vaccination of African infants in a setting with high HIV prevalence was associated with PCV 13-serotype colonization reduction, including among unvaccinated HIV-infected women.
Despite approximately 2.6 million stillbirths occurring annually, there is a paucity of systematic biological investigation and consequently knowledge on the causes of these deaths in low- and ...middle-income countries (LMICs). We investigated the utility of minimally invasive tissue sampling (MITS), placental examination, and clinical history, in attributing the causes of stillbirth in a South African LMIC setting.
This prospective, observational pilot study undertook sampling of brain, lung, and liver tissue using core biopsy needles, blood and cerebrospinal fluid collection, and placental examination. Testing included microbial culture and/or molecular testing and tissue histological examination. The cause of death was determined for each case by an international panel of medical specialists and categorized using the World Health Organization's International Classification of Diseases, Tenth Revision application to perinatal deaths.
A cause of stillbirth was identifiable for 117 of 129 (90.7%) stillbirths, including an underlying maternal cause in 63.4% (n = 83) and an immediate fetal cause in 79.1% (n = 102) of cases. The leading underlying causes of stillbirth were maternal hypertensive disorders (16.3%), placental separation and hemorrhage (14.0%), and chorioamnionitis (10.9%). The leading immediate causes of fetal death were antepartum hypoxia (35.7%) and fetal infection (37.2%), including due to Escherichia coli (16.3%), Enterococcus species (3.9%), and group B Streptococcus (3.1%).
In this pilot, proof-of-concept study, focused investigation of stillbirth provided granular detail on the causes thereof in an LMIC setting, including provisionally highlighting the largely underrecognized role of fetal sepsis as a dominant cause.
The limited capability in most low- to middle-income countries to study the benefit of pneumococcal conjugate vaccine (PCV) in protecting against invasive pneumococcal disease (IPD) calls for ...alternate strategies to assess this. We used a mathematical model to predict the direct and indirect effectiveness of PCV by analyzing serotype-specific colonization prevalence and IPD incidence prior to and following childhood PCV immunization in South Africa. We analyzed IPD incidence from 2005 to 2012 and colonization studies undertaken in human immunodeficiency virus (HIV)-uninfected and HIV-infected child-mother dyads from 2007 to 2009 (pre-PCV era), in 2010 (7-valent PCV era), and in 2012 (13-valent PCV era). We compared the model-predicted changes in IPD incidence with observed changes in IPD incidence, according to HIV status, in children aged 3 months-5 years and in women aged 18-45 years. We observed reductions in vaccine-serotype colonization and IPD due to vaccine serotypes among children and women after PCV introduction. Using the changes in vaccine-serotype colonization data, the model-predicted changes in vaccine-serotype IPD incidence rates were similar to the observed changes in PCV-unvaccinated children and adults, but not among children under age 24 months. Surveillance of colonization prior to and following PCV use can be used to impute the indirect protection afforded by PCV in unvaccinated age groups, including those in high-HIV-prevalence settings.
BACKGROUND:Pneumococcal conjugate vaccine (PCV) immunization of children decreases their risk of nasopharyngeal acquisition of vaccine serotypes. We studied the impact of routine infant PCV ...immunization alone on the epidemiology of nasopharyngeal pneumococcal colonization among a rural African community with high prevalence of HIV positivity.
METHODS:Two cross-sectional surveys were undertaken in a rural South African community from May to October 2009 (period 1) and 2011 (period 2). Seven-valent PCV was introduced into the public immunization program for infants in April 2009, without catch-up campaign for older children. Randomly selected households with at least 1 child <2 years of age were recruited. Nasopharyngeal swabs from all consenting household members were obtained for Streptococcus pneumoniae culture and serotyping by Quellung method.
RESULTS:The median ages (SD) of children enrolled were 4.32 (SD, 3.4) and 3.80 (SD, 3.4) years in periods 1 and 2, respectively. Overall, the prevalence of vaccine serotype colonization declined from 18.3% (368/2010) in period 1 to 11.4% (418/3659) by period 2 (P < 0.0001). This included reductions (adjusted risk ratio) of 50% 95% confidence interval (95% CI)0.42–0.59, 34% (95% CI0.48–0.92) and 64% (95% CI0.18–0.74) in age groups <2 years, 6–12 years and adults. The prevalence of vaccine serotype colonization among primary caregivers decreased from 10.2% to 5.4% (P ≤ 0.001) by period 2. The prevalence of nonvaccine serotype colonization increased by 35% (95% CI1.17–1.56) among <2-year-old children by period 2, while it declined by 45–54% among adolescents and adults.
CONCLUSIONS:An indirect effect of PCV7 was realized in a high HIV prevalence setting within 2 years of PCV introduction. The unexpected decline in nonvaccine serotypes colonization among adolescents/adults may indicate lag in replacement colonization by nonvaccine serotypes in this group.
To assess the impact of immunization with pneumococcal conjugate vaccines on all-cause pneumonia hospitalizations among children in Soweto, South Africa.
We used data collected at the Chris Hani ...Baragwanath Hospital in Soweto between 2006 and 2014 - i.e. before and after April 2009, when a pneumococcal conjugate vaccine was first included in South Africa's routine immunization programme. Using a Bayesian generalized seasonal autoregressive moving-average model and the data collected in 2006-2008, we estimated the numbers of children that would have been hospitalized for pneumonia between 2010 and 2014 if no pneumococcal conjugate vaccines had been used. These estimates were then compared with the corresponding numbers of hospitalizations observed.
Between 2006 and 2014, 26 778 children younger than five years - including 3388 known to be infected with human immunodeficiency virus (HIV) - were admitted to the study hospital for pneumonia. We estimated that, for the children known to be infected with HIV and for the other children, pneumococcal conjugate vaccines reduced the numbers of hospitalizations for pneumonia in 2014 by 33% (50% credible interval, CrI: 6 to 52) and 39% (50% CrI: 24 to 50), respectively. In the study hospital in 2012-2014, as a result of immunizations with these vaccines, there were an estimated 3100 fewer pneumonia hospitalizations of children younger than five years.
In our study hospital, following the introduction of pneumococcal conjugate vaccines into the national immunization programme, there were significant reductions in pneumonia hospitalizations among children.
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