Maternal immunisation against Group B Streptococcus: A global analysis of health impact and cost-effectiveness

How Can We Accelerate Maternal Vaccination Globally?

New maternal vaccines could reduce infant deaths at and after birth, especially in low- and middle-income countries. Work is underway to prepare for new maternal vaccines globally, and the Maternal Immunization Readiness Network for Africa and Asia will support in-country preparation in several low- and middle-income countries. However, the impact of new maternal vaccines will only be realized with supportive policy recommendations and sufficient financing for the development of maternal immunization platforms.

Characterization of clinical infection and drug resistance of group B streptococcus in Chengdu, China

OBJECTIVE

To investigate the clinical infection characteristics and antibiotic resistance of Group B Streptococcus (Streptococcus agalactiae, GBS) in Chengdu, China, from 2019 to 2021, as well as to provide data to support rational clinical drug use.

METHODS

This was a retrospective study to collect 203 culture-positive GBS strains isolated from January 2019 to December 2021 in Chengdu, China, all of which were identified by the VITEK 2 Compact automated microbial Bacterial identification instrument. Data were derived using WHONET 5.6 software. The sample type and ward distribution were counted. Pregnant women and newborns were screened from the original data and their pregnancy outcomes were calculated respectively.

RESULTS

GBS strains were mainly concentrated in obstetrics and neonatology departments, accounting for 40.9 % and 33.5 %. The types of specimens were mainly vaginal secretions, amniotic fluid and sputum, accounting for 25.6 %, 26.1 % and 18.7 %, respectively. Chorioamnionitis, premature rupture of membranes and preterm delivery occurred mainly in pregnant women after infection, accounting for 44.4 %, 31.5 % and 24.1 %. Neonates, on the other hand, were mainly diagnosed with neonatal pneumonia, neonatal sepsis, respiratory failure and septic meningitis, accounting for 91.8 %, 61.2 %, 44.9 % and 16.3 % of all positive neonates. 840 pregnant women were screened for GBS colonization from 2019 to 2021, and a total of 108 GBS positive pregnant women were identified, with a GBS colonization rate of 12.9 %. A total of 9 neonates from 108 GBS positive pregnant women developed early-onset disease. The morbidity in neonates was 8.3 %. No strains resistant to penicillin and ampicillin were found, while the resistance rates of tetracycline and clindamycin were higher than 50 %, respectively 60.1 % and 53.2 %.

CONCLUSION

GBS infection mainly affected pregnant women and newborns in Chengdu, China, which can lead to adverse maternal and infant outcomes. Attention should be paid to strengthening general screening of GBS in perinatal urogenital secretions and the prevention strategy of IAP (intrapartum antibiotic prophylaxis). Antimicrobial therapy should be administered with appropriate antibiotics. Penicillin was still the first line drug for the treatment of GBS. These initiatives were important to reduce mother-to-child transmission and neonatal infections.

Neonatal bacterial sepsis

Neonatal sepsis remains one of the key challenges of neonatal medicine, and together with preterm birth, causes almost 50% of all deaths globally for children younger than 5 years. Compared with advances achieved for other serious neonatal and early childhood conditions globally, progress in reducing neonatal sepsis has been much slower, especially in low-resource settings that have the highest burden of neonatal sepsis morbidity and mortality. By contrast to sepsis in older patients, there is no universally accepted neonatal sepsis definition. This poses substantial challenges in clinical practice, research, and health-care management, and has direct practical implications, such as diagnostic inconsistency, heterogeneous data collection and surveillance, and inappropriate treatment, health-resource allocation, and education. As the clinical manifestation of neonatal sepsis is frequently non-specific and the current diagnostic standard blood culture has performance limitations, new improved diagnostic techniques are required to guide appropriate and warranted antimicrobial treatment. Although antimicrobial therapy and supportive care continue as principal components of neonatal sepsis therapy, refining basic neonatal care to prevent sepsis through education and quality improvement initiatives remains paramount.

Current research update on group B streptococcal infection related to obstetrics and gynecology

Group B streptococcal (GBS) is a Gram-positive bacterium that is commonly found in the gastrointestinal tract and urogenital tract. GBS infestation during pregnancy is a significant contributor to maternal and neonatal morbidity and mortality globally. This article aims to discuss the infectious diseases caused by GBS in the field of obstetrics and gynecology, as well as the challenges associated with the detection, treatment, and prevention of GBS.

Distributions of candidate vaccine Targets, virulence Factors, and resistance features of invasive group B Streptococcus using Whole-Genome Sequencing: A Multicenter, population-based surveillance study

BACKGROUND

Group B Streptococcus (GBS) is a leading cause of morbidity and mortality in young infants worldwide. This study aimed to investigate candidate GBS vaccine targets, virulence factors, and antimicrobial resistance determinants.

METHODS

We used whole-genome sequencing to characterize invasive GBS isolates from infants < 3 months of age obtained from a multicenter population-based study conducted from 2015 to 2021 in China.

RESULTS

Overall, seven serotypes were detected from 278 GBS isolates, four (Ia, Ib, III, V) of which accounted for 97.8 %. We detected 30 sequence types (including 10 novel types) that were grouped into six clonal complexes (CCs: CC1, CC10, CC17, CC19, CC23 and CC651); three novel ST groups in CC17 were detected, and the rate of CC17, considered a hyperinvasive neonatal clone complex, was attached to 40.6 % (113/278). A total of 98.9 % (275/278) of isolates harbored at least one alpha-like protein gene. All GBS isolates contained at least one of three pilus backbone determinants and the pilus types PI-2b and PI-1 + PI-2a accounted for 79.8 % of the isolates. The 112 serotype III/CC17 GBS isolates were all positive for hvgA. Most of the isolates (75.2 %) were positive for serine-rich repeat glycoprotein determinants (srr1or srr2). Almost all isolates possessed cfb (99.6 %), c1IE (100 %), lmb (95.3 %) or pavA (100 %) gene. Seventy-seven percent of isolates harboured more than three antimicrobial resistance genes with 28.4 % (79/278) gyrA quinoloneresistancedeterminants mutation, 83.8 % (233/278) carrying tet cluster genes and 77.3 % (215/278) carrying erm genes which mediated fluoroquinolone, tetracycline and clindamycin resistance, respectively."

CONCLUSIONS

The findings from this large whole-genome sequence of GBS isolates establish important baseline data required for further surveillance and evaluating the impact of future vaccine candidates.

GBS vaccines in the UK: a round table discussion

Background

Group B streptococcus (GBS) remains a leading cause of infant sepsis, meningitis and death despite intrapartum antibiotic prophylaxis. A vaccine is urgently required, and two candidates are in advanced clinical trials. For successful GBS vaccine implementation, especially if a vaccine is licensed based on an immunological threshold, there must be cross-sector engagement, effective advocacy, robust plans for phase IV studies and equitable access.

Meeting

A round-table discussion, held at St George's University of London, reviewed the current position of GBS vaccines in the UK context, focusing on phase IV plans, convening a diverse group of stakeholders from across the UK, with a role in GBS vaccine licensure, advocacy, implementation or effectiveness evaluation.Presentations outlined the latest UK epidemiology, noting the rising infant invasive GBS (iGBS) infection rates from 1996 to 2021 for both early and late onset disease, with the highest disease rates in Black infants (1.1/1000 livebirths vs white infants (0.81/1000 livebirths). Potential coverage of the candidate vaccines was high (>95%). Regulatory input suggested that EU regulators would consider waiving the need for a pre-licensure efficacy study if a putative correlate of protection could be adequately justified. Phase IV study methodologies for a GBS vaccine were considered, largely based on previous UK maternal vaccine assessments, such as a nationwide cohort study design using a vaccine register and a maternal services dataset. Other strategies were also discussed such as a cluster or stepped-wedge randomised trial to evaluate implementation outcomes. Opportunities for advocacy, education and engagement with additional key partners were discussed and identified.

Conclusions

With an approved GBS vaccine a near possibility, planning of phase IV studies and identification of critical barriers to implementation are urgently needed. Cross-sector engagement is essential and will facilitate a successful pathway.

Long-term healthcare utilisation, costs and quality of life after invasive group B Streptococcus disease: a cohort study in five low-income and middle-income countries

INTRODUCTION

There are no published data on the long-term impact of invasive group B Streptococcus disease (iGBS) on economic costs or health-related quality of life (HRQoL) in low-income and middle-income countries. We assessed the impact of iGBS on healthcare utilisation, costs and HRQoL in Argentina, India, Kenya, Mozambique and South Africa.

METHODS

Inpatient and outpatient visits, out-of-pocket (OOP) healthcare payments in the 12 months before study enrolment, and health-state utility of children and caregivers (using the EuroQol 5-Dimensions-3-Level) were collected from iGBS survivors and an unexposed cohort matched on site, age at recruitment and sex. We used logistic or Poisson regression for analysing healthcare utilisation and zero-inflated gamma regression models for family and health system costs. For HRQoL, we used a zero-inflated beta model of disutility pooled data.

RESULTS

161 iGBS-exposed and 439 unexposed children and young adults (age 1-20) were included in the analysis. Compared with unexposed participants, iGBS was associated with increased odds of any healthcare utilisation in India (adjusted OR 11.2, 95% CI 2.9 to 43.1) and Mozambique (6.8, 95% CI 2.2 to 21.1) and more frequent healthcare visits (adjusted incidence rate ratio (IRR) for India 1.7 (95% CI 1.4 to 2.2) and for Mozambique 6.0 (95% CI 3.2 to 11.2)). iGBS was also associated with more frequent days in inpatient care in India (adjusted IRR 4.0 (95% CI 2.3 to 6.8) and Kenya 6.4 (95% CI 2.9 to 14.3)). OOP payments were higher in the iGBS cohort in India (adjusted mean: Int$682.22 (95% CI Int$364.28 to Int$1000.16) vs Int$133.95 (95% CI Int$72.83 to Int$195.06)) and Argentina (Int$244.86 (95% CI Int$47.38 to Int$442.33) vs Int$52.38 (95% CI Int$-1.39 to Int$106.1)). For all remaining sites, differences were in the same direction but not statistically significant for almost all outcomes. Health-state disutility was higher in iGBS survivors (0.08, 0.04-0.13 vs 0.06, 0.02-0.10).

CONCLUSION

The iGBS health and economic burden may persist for years after acute disease. Larger studies are needed for more robust estimates to inform the cost-effectiveness of iGBS prevention.

A Practical Guide to Full Value of Vaccine Assessments

Articulating the wide range of health, social and economic benefits that vaccines offer may help to overcome obstacles in the vaccine development pipeline. A framework to guide the assessment and communication of the value of a vaccine-the Full Value of Vaccine Assessment (FVVA)-has been developed by the WHO. The FVVA framework offers a holistic assessment of the value of vaccines, providing a synthesis of evidence to inform the public health need of a vaccine, describing the supply and demand aspects, its market and its impact from a health, financial and economic perspective. This paper provides a practical guide to how FVVAs are developed and used to support investment in vaccines, ultimately leading to sustained implementation in countries. The FVVA includes a range of elements that can be broadly categorised as synthesis, vaccine development narrative and defining vaccine impact and value. Depending on the features of the disease/vaccine in question, different elements may be emphasised; however, a standardised set of elements is recommended for each FVVA. The FVVA should be developed by an expert group who represent a range of stakeholders, perspectives and geographies and ensure a fair, coherent and evidence-based assessment of vaccine value.

Group B Streptococcal Disease in Infants in Japan

This review describes the epidemiology of group B Streptococcus (GBS) infection in infants in Japan and discusses unresolved issues and future perspectives. Guidelines for the prevention of vertical transmission in Japan were implemented in 2008. The incidence of early-onset disease in Japan has remained stable at approximately 0.10/1000 livebirths or less, which is lower than in Europe and North America. The incidence of late-onset disease is also low, but has increased over the last decade, with an estimated 0.29/1000 livebirths in 2020. National surveillance studies in 2011-2015 and 2016-2020 reported case fatality rates of 4.5% and 6.5% for early-onset disease and 4.4% and 3.0% for late-onset disease, respectively. Sequelae of neurodevelopmental impairments were considerably associated with infants who developed meningitis. Predominant neonatal invasive strains have remained in the following order of serotypes: III, Ia, Ib and V, for the past 30 years. Conversely, the predominant serotypes of maternal colonization strains markedly changed from serotypes VI and VIII around 2000 to serotypes Ia, Ib, III and V over the last decade. Recurrence rates among infants < 1-year-old were estimated to be 2.8%-3.7%, and preterm birth and antenatal maternal GBS colonization were risk factors for recurrence. Several unresolved issues remain. First, the exact disease burden remains unclear because Japan does not have a nationwide system to register all infants affected by invasive GBS disease, and even population-based surveys are limited to up to 10 of the 47 prefectures. Others include low adherence to prevention guidelines of vertical transmission and the development of strategies based on Japanese epidemiological evidence rather than the Center for Disease Control and Prevention guidelines. The effectiveness of introducing maternal vaccines in Japan, where the disease incidence is low, needs to be carefully verified.

Self-collection of samples for group B streptococcus testing during pregnancy: a systematic review and meta-analysis

BACKGROUND

Sample self-collection for reproductive tract infection diagnosis has been found to offer greater convenience, privacy, autonomy, and expanded access to testing in non-pregnant adults. This review aimed to determine whether sample self-collection is as accurate as provider-collection for detection of group B streptococcus colonisation in pregnancy and whether a strategy of self-collection compared to provider-collection might improve maternal and neonatal health outcomes.

METHODS

We searched CINAHL Plus, Medline, EMBASE, Maternity and Infant Care Database, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews in June 2022. Eligible studies compared self-collected and provider-collected samples taken from the same participants or participants randomised to either self-collection or provider-collection for reproductive tract infection testing using the same test and testing method in pregnant individuals. We included trials and observational studies. Reviewers assessed risk of bias using the QUADAS-2 checklist and independently extracted data. Sensitivity and specificity for group B streptococcus colonisation of self-collected compared to provider-collected samples were pooled using a bivariate, random-effects, meta-analytic model. This review was registered with PROSPERO (CRD42023396573).

RESULTS

The search identified 5909 references, of which eleven diagnostic accuracy group B streptococcus studies were included (n = 3269 participants). No studies assessed the effects of self-collection in pregnancy on health outcomes. All studies had high or unclear risk of bias. Pooled sensitivities of self-collected samples for group B streptococcus detection were 82% (95% CI: 66-91%; I2 = 68.85%) in four trials (n = 1226) and 91% (95% CI: 83-96%; I2 = 37.38%) in seven non-randomised studies (n = 2043). Pooled specificities were 99% (95% CI: 98-99%; I2 = 12.08%) and 97% (95% CI: 94-99%; I2 = 72.50%), respectively.

CONCLUSIONS

Self-collected samples for group B streptococcus detection in pregnancy had high specificity compared to provider-collection, but lower sensitivity, particularly for included trials. Studies investigating the effect of self-collection on health outcomes, and further higher quality trials comparing accuracy of self-collection to provider-collection, are required.

Near-term pregnant women in the Dominican Republic experience high rates of Group B Streptococcus rectovaginal colonization with virulent strains

Maternal colonization with Group B Streptococcus (GBS) is an important cause of stillbirth, prematurity, and serious infection and death in infants worldwide. Resource constraints limit prevention strategies in many regions. Maternal GBS vaccines in development could be a more accessible prevention strategy, but data on geographic variations in GBS clones are needed to guide development of a broadly effective vaccine. In the Dominican Republic (DR), limited data suggest that pregnant women experience GBS colonization at rates among the highest globally. We aimed to determine the prevalence of maternal rectovaginal GBS colonization and describe clonal characteristics of colonizing strains in the DR. A cross-sectional study assessed rectovaginal GBS colonization in 350 near-term pregnant women presenting for routine prenatal care at an urban tertiary center in the DR. Rectovaginal samples were tested with chromogenic Strep B Carrot Broth and cultured for confirmatory whole-genome sequencing. In a secondary analysis, participants' demographics and histories were assessed for association with GBS colonization. Rectovaginal GBS colonization occurred in 26.6% of women. Serotypes Ia, Ib, II, III, IV, and V were detected, with no one serotype predominating; serotype III was identified most frequently (21.5%). Virulent and emerging strains were common, including CC17 (15.1%) and ST1010 (17.2%). In this first characterization of maternal GBS serotypes in the DR, we found high rates of rectovaginal colonization including with virulent and emerging GBS strains. The serotypes observed here are all targeted by candidate hexavalent GBS vaccines, suggesting effective protection in the DR.

Cost-effectiveness analysis of maternal vaccination against Group B streptococcus in Japan

Background

Group B Streptococcus (GBS) is a leading pathogen causing life-threatening bacterial infections in neonates (early- or late-onset) and infants, and is associated with preterm and stillbirth. Japan introduced national guidelines to reduce early-onset neonatal GBS disease, with universal prenatal screening and intrapartum antimicrobial prophylaxis (IAP). However, screening/IAP does not prevent GBS associated late-onset disease, preterm or stillbirth. Maternal GBS vaccines in development are targeted at infant GBS disease but may provide benefit across perinatal outcomes. We aimed to assess cost-effectiveness of a future maternal GBS vaccine, for a base case prevention of infant GBS disease in combination with screening/IAP compared to screening/IAP alone.

Methods

We used a decision tree model to estimate cases of infant GBS disease, deaths, and neuro-developmental impairment (NDI), GBS-related stillbirths, and the associated costs and loss in Quality-Adjusted Life Years (QALYs). We calculate the threshold price at which a vaccine would be cost-effective assuming a cost-effectiveness threshold of ¥5 million/QALY. We explored the potential benefit of a maternal GBS vaccine that also prevents preterm birth in a scenario analysis.

Results

Maternal GBS vaccination in Japan could prevent an additional 142 infant GBS cases annually, including 5 deaths and 21 cases of NDI, and 13 stillbirths compared to screening/IAP alone. The incremental cost-effectiveness ratio (ICER) was ¥3.78 million/QALY with a vaccine cost of ¥5,000/dose. If the QALY lost for stillbirth is included, the ICER is reduced to ¥1.78 million/QALY. Median threshold vaccine price was ¥6,900 per dose (95 % uncertainty interval ¥5,100 to ¥9,200 per dose). If maternal GBS vaccination also prevented half of GBS-associated preterm, the ICER would be reduced to ¥1.88 million/QALY.

Conclusions

An effective maternal GBS vaccine is likely to be considered cost-effective in Japan at a price of ¥5,000/dose. Effectiveness against other adverse perinatal outcomes would increase health benefits and cost-effectiveness.

Early-onset group B streptococcal disease in African countries and maternal vaccination strategies

Invasive group B streptococcal (GBS) disease is the commonest perinatally-acquired bacterial infection in newborns; the burden is higher in African countries where intrapartum antibiotic prophylaxis strategies are not feasible. In sub-Saharan Africa, almost one in four newborns with GBS early-onset disease will demise, and one in ten survivors have moderate or severe neurodevelopmental impairment. A maternal GBS vaccine to prevent invasive GBS disease in infancy is a pragmatic and cost-effective preventative strategy for Africa. Hexavalent polysaccharide protein conjugate and Alpha family surface protein vaccines are undergoing phase II clinical trials. Vaccine licensure may be facilitated by demonstrating safety and immunological correlates/thresholds suggestive of protection against invasive GBS disease. This will then be followed by phase IV effectiveness studies to assess the burden of GBS vaccine preventable disease, including the effect on all-cause neonatal infections, neonatal deaths and stillbirths.

Group B Streptococcus infection-induced ovarian vein thrombosis identified during cesarean section: A case report and a literature review

RATIONALE

Ovarian vein thrombosis (OVT) is a rare yet potentially life-threatening condition associated with thromboembolic events. Group B Streptococcus (GBS) is a type of β-hemolytic Gram-positive bacterium known for asymptomatic colonization in the lower genital and gastrointestinal tracts. Here we reported a 35-year-old multiparous woman with gestational diabetes who suffered from placental abruption, stillbirth, OVT, septic shock, and renal failure due to severe GBS infection.

PATIENT CONCERNS

A 35-year-old woman with gestational diabetes presented with acute and sustained lower abdominal cramping, vaginal bleeding, and fever at 35 gestational weeks.

DIAGNOSES

Based on preoperative ultrasound and intraoperative findings, the patient was diagnosed with placental abruption, intrauterine fetal demise, and right OVT. GBS was cultured from the amniotic fluid obtained during cesarean section.

INTERVENTIONS

The patient underwent a right adnexectomy during a cesarean section and received intravenous antibiotics. Subsequently, an ultrasound-guided uterine curettage was performed due to recurrent fever.

OUTCOMES

After a prolonged course of intravenous antibiotics for over a month, the patient recovered and was discharged from the hospital.

LESSONS

This case underscores the need for early initiation of anticoagulant protocols in cases of OVT, particularly when GBS infection is identified as a predisposing factor. Further research and awareness are warranted to better understand the relationship between GBS infection and OVT and to optimize management strategies in such cases.