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There are between 11 and 27 million estimated cases of enteric fever worldwide every year, and 75,000–220,000 deaths. Could vaccination stop the spread of these diesases in the environment?
Development and preclinical analysis of lipopolysaccharide-based glycoconjugate vaccine candidates against Coxiella burnetti
Q fever is a zoonosis caused by the Gram-negative bacterium Coxiella burnetii. Currently, there is only one licensed human vaccine for Q fever, but its high level of reactogenicity necessitates the urgent need for developing a safer and efficacious alternative. Prior research has highlighted the utility of anti-C. burnetii phase I (smooth form) lipopolysaccharide (LPS) IgG antibodies in conferring protection against Q fever. Drawing on this foundation, this thesis describes the generation and evaluation of novel LPS-based glycoconjugate vaccine candidates aimed at combating Q fever. The initial phase of the work involved synthesising the vaccine candidates using LPS extracted from inactivated C. burnetii. Purified LPS was conjugated with carrier proteins including tetanus toxoid heavy chain (TThc) and CRM197, using two different chemistries. The selection of carrier proteins and conjugation chemistries was informed by their scalability and potential for clinical development. As a result, this work led to the development of two LPS-based glycoconjugate vaccine candidates, QCON-CT and QCON-ET. The capacity of these vaccine candidates to induce a functional immune response was subsequently evaluated using a mouse model. Both vaccine candidates were capable of eliciting a serum anti-C. burnetii phase I LPS IgG response. In particular, QCON-CT, when formulated with Alum adjuvant, induced significantly higher anti-LPS IgG titres compared with an existing licensed inactivated veterinary vaccine. In addition, a comprehensive in silico pipeline was developed using a dataset generated from a randomised, phase 2b, typhoid fever controlled human infection model (CHIM) study to evaluate molecular signatures post-vaccination. In this study, a plain polysaccharide-based vaccine was compared with a glycoconjugate vaccine containing the same polysaccharide antigen. This in turn provides a large dataset for transcriptomic analysis development. Methods were developed to contrast immunological profiles of the two vaccine types, quantifying various metrics including differential gene expression, T cell-dependent functions induced by the glycoconjugate vaccine, and likely antigen-specific antibody clonotype abundances. Establishing this pipeline not only aided the understanding of typhoid fever by identifying the very first molecular markers associated with vaccine-induced protection, but also enabled RNA-Seq data generated from the Q fever mouse study to be leveraged by transcriptomic analyses. Using this in silico pipeline, it was determined that both glycoconjugate vaccine candidates against Q fever induced a convergent humoral response, characterised by the upregulation of several likely LPS-specific B cell receptor (BCR) clonotypes. These findings, in alignment with the in vitro readouts, indicate the promising effectiveness that can be achieved by the LPS-based glycoconjugate vaccine approach. Overall, a path towards further clinical development of the Q fever glycoconjugate vaccine candidates is delineated by the results generated in this thesis, highlighting their potential in addressing global public health needs by facilitating the control and prevention of Q fever outbreaks worldwide. The mechanistic insights and methodologies developed herein not only provide a framework for future vaccine research, but also hold promise for application in combating many other infectious diseases.
Feasibility and utility of a combined nasogastric-tube-and-string-test device for bacteriologic confirmation of pulmonary tuberculosis in young children.
For microbiological confirmation of pediatric pulmonary tuberculosis (PTB), gastric aspirates (GA) are often operationally unfeasible without hospitalization, and the encapsulated orogastric string test is not easily swallowed in young children. The Combined-NasoGastric-Tube-and-String-Test (CNGTST) enables dual collection of GA and string specimens. In a prospective cohort study in Kenya, we examined its feasibility in children under five with presumptive PTB and compared the bacteriological yield of string to GA. Paired GA and string samples were successfully collected in 95.6 % (281/294) of children. Mycobacterium tuberculosis was isolated from 7.0 % (38/541) of GA and 4.3 % (23/541) of string samples, diagnosing 8.2 % (23/281) of children using GA and 5.3 % (15/281) using string. The CNGTST was feasible in nearly all children. Yield from string was two-thirds that of GA despite a half-hour median dwelling time. In settings where the feasibility of hospitalisation for GA is uncertain, the string component can be used to confirm PTB.
Clinical trial capacity building in a pandemic—outcome of a rapid site readiness project in Latin America
BackgroundLatin America (Latam) has a tradition of large-scale vaccine trials. Because of fluctuating demand, many sites have downsized their infrastructure. Therefore, BMGF launched a clinical trial site-readiness initiative early in the coronavirus-2019 (COVID-19) pandemic including Latam countries between August and September 2020. This survey evaluated clinical development performance measures pre/post initiative (September 2022).Results20/21 prequalified sites participated in COVID-19 vaccine/drug development trials. 156 clinical trials (140 COVID-19 vaccine/drug trials) were initiated in the 2 years since prequalification, compared to 176 in the 5 years before. 33,428/37,810 participants were included in COVID-19 programs. The number of enrolled subjects/day across sites quadrupled from 15 (1–35) to 63 (5–300). The dropout rate was 6.8%. Study approval timelines were reduced from 60 (12–120) to 35 (5–90) days. Mean qualified staff was increased from 24 (6–80) to 88 (22–180).ConclusionClinical trial sites across Latam were successfully prequalified to participate in COVID-19 developments. For the 100 days mission of vaccine availability in a new pandemic sufficient and well-trained clinical trial sites readily available are essential. This is only achievable if sites—especially in low/middle-income countries—are maintained active through a constant flow of vaccine studies.
Plasma Protein Biomarkers Distinguish Multisystem Inflammatory Syndrome in Children From Other Pediatric Infectious and Inflammatory Diseases.
BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) is a rare but serious hyperinflammatory complication following infection with severe acute respiratory syndrome coronavirus 2. The mechanisms underpinning the pathophysiology of MIS-C are poorly understood. Moreover, clinically distinguishing MIS-C from other childhood infectious and inflammatory conditions, such as Kawasaki disease or severe bacterial and viral infections, is challenging due to overlapping clinical and laboratory features. We aimed to determine a set of plasma protein biomarkers that could discriminate MIS-C from those other diseases. METHODS: Seven candidate protein biomarkers for MIS-C were selected based on literature and from whole blood RNA sequencing data from patients with MIS-C and other diseases. Plasma concentrations of ARG1, CCL20, CD163, CORIN, CXCL9, PCSK9 and ADAMTS2 were quantified in MIS-C (n = 22), Kawasaki disease (n = 23), definite bacterial (n = 28) and viral (n = 27) disease and healthy controls (n = 8). Logistic regression models were used to determine the discriminatory ability of individual proteins and protein combinations to identify MIS-C and association with severity of illness. RESULTS: Plasma levels of CD163, CXCL9 and PCSK9 were significantly elevated in MIS-C with a combined area under the receiver operating characteristic curve of 85.7% (95% confidence interval: 76.6%-94.8%) for discriminating MIS-C from other childhood diseases. Lower ARG1 and CORIN plasma levels were significantly associated with severe MIS-C cases requiring inotropes, pediatric intensive care unit admission or with shock. CONCLUSION: Our findings demonstrate the feasibility of a host protein biomarker signature for MIS-C and may provide new insight into its pathophysiology.
Multi-omics analysis reveals COVID-19 vaccine induced attenuation of inflammatory responses during breakthrough disease.
The immune mechanisms mediating COVID-19 vaccine attenuation of COVID-19 remain undescribed. We conducted comprehensive analyses detailing immune responses to SARS-CoV-2 virus in blood post-vaccination with ChAdOx1 nCoV-19 or a placebo. Samples from randomised placebo-controlled trials (NCT04324606 and NCT04400838) were taken at baseline, onset of COVID-19-like symptoms, and 7 days later, confirming COVID-19 using nucleic amplification test (NAAT test) via real-time PCR (RT-PCR). Serum cytokines were measured with multiplexed immunoassays. The transcriptome was analysed with long, short and small RNA sequencing. We found attenuation of RNA inflammatory signatures in ChAdOx1 nCoV-19 compared with placebo vaccinees and reduced levels of serum proteins associated with COVID-19 severity. KREMEN1, a putative alternative SARS-CoV-2 receptor, was downregulated in placebo compared with ChAdOx1 nCoV-19 vaccinees. Vaccination ameliorates reductions in cell counts across leukocyte populations and platelets noted at COVID-19 onset, without inducing potentially deleterious Th2-skewed immune responses. Multi-omics integration links a global reduction in miRNA expression at COVID-19 onset to increased pro-inflammatory responses at the mRNA level. This study reveals insights into the role of COVID-19 vaccines in mitigating disease severity by abrogating pro-inflammatory responses associated with severe COVID-19, affirming vaccine-mediated benefit in breakthrough infection, and highlighting the importance of clinically relevant endpoints in vaccine evaluation.
Nasopharyngeal Carriage of Pneumococcus in Children in England up to 10 Years After 13-Valent Pneumococcal Conjugate Vaccine Introduction: Persistence of Serotypes 3 and 19A and Emergence of 7C.
<h4>Background</h4>Monitoring changes in pharyngeal carriage of pneumococcus in children following 13-valent pneumococcal conjugate vaccine (PCV13) introduction in the United Kingdom in 2010 informs understanding of patterns of invasive pneumococcal disease (IPD) incidence.<h4>Methods</h4>Nasopharyngeal swabs from healthy children vaccinated with PCV13 according to schedule (2, 4, and 12 months) were cultured and serotyped. Results for children aged 13-48 months were compared between 2014-2015 and 2017-2019 and with children aged 6-12 months (2017-2020). Blood was obtained from a subset of children for pneumococcal serotype-specific immunoglobulin G (IgG).<h4>Results</h4>Total pneumococcal carriage at 13-48 months was 47.9% (473/988) in 2014-2015 and 51.8% (412/795) in 2017-2019 (P = .10); at age 6-12 months this value was 44.6% (274/615). In 2017-2019, 2.9% (95% confidence interval, 1.8%-4.3%) of children aged 13-48 months carried PCV13 serotypes (mainly 3 [1.5%] and 19A [0.8%]) and >20% carried the additional 20-valent PCV (PCV20) serotypes. Similar proportions of children had IgG ≥0.35 IU/mL for each serotype in 2014-2015 and 2017-2019. Serotype 7C carriage increased significantly (P < .01) between 2014-2015 and 2017-2019. Carriage of PCV20 serotypes 8 and 12F, both major causes of IPD, was rare.<h4>Conclusions</h4>Introduction of PCV20, if licensed for children, could significantly change the composition of pneumococcal serotypes carried in the pharynx of UK children.<h4>Clinical trials registration</h4>NCT03102840.
Serum HCoV-spike specific antibodies do not protect against subsequent SARS-CoV-2 infection in children and adolescents.
SARS-CoV-2 infections in children are generally asymptomatic or mild and rarely progress to severe disease and hospitalization. Why this is so remains unclear. Here we explore the potential for protection due to pre-existing cross-reactive seasonal coronavirus antibodies and compare the rate of antibody decline for nucleocapsid and spike protein in serum and oral fluid against SARS-CoV-2 within the pediatric population. No differences in seasonal coronaviruses antibody concentrations were found at baseline between cases and controls, suggesting no protective effect from pre-existing immunity against seasonal coronaviruses. Antibodies against seasonal betacoronaviruses were boosted in response to SARS-CoV-2 infection. In serum, anti-nucleocapsid antibodies fell below the threshold of positivity more quickly than anti-spike protein antibodies. These findings add to our understanding of protection against infection with SARS-CoV-2 within the pediatric population, which is important when considering pediatric SARS-CoV-2 immunization policies.
Intravenous immunoglobulin treatment for encephalitis in children aged 6 months to 16 years: the IgNiTE RCT
Background There are data suggesting that intravenous immunoglobulin treatment has some benefit for certain forms of encephalitis but robust evidence from large randomised controlled trials in children with all-cause encephalitis is lacking. Objective To evaluate whether intravenous immunoglobulin treatment improves neurological outcomes in childhood encephalitis when given early in the illness. Design Phase 3b, investigator-initiated, randomised, double-blind, placebo-controlled trial of intravenous immunoglobulin for the treatment of encephalitis in children. Setting Twenty-one NHS Hospitals in the UK. Participants Children aged 6 months to 16 years with a diagnosis of acute or sub-acute encephalitis. Intervention Two doses (1 g/kg/dose) of either intravenous immunoglobulin or matching placebo, given 24–36 hours apart, in addition to standard treatment. Main outcome measure Participants were followed up for 12 months (+/– 4 weeks) after randomisation. The primary outcome measure was a ‘good recovery’ defined as a score of ≤ 2 on the Paediatric Glasgow Outcome Score Extended at 12 months after randomisation. Secondary outcomes The secondary outcomes were clinical, neurological, neuroimaging and neuropsychological results, identification of the proportion of children with immune-mediated encephalitis, and intravenous immunoglobulin safety data. Results We planned to recruit 308 children over a 42-month period. After enrolment of 18 participants (8 male; 44%) over 21 months (from December 2015 to September 2017), funding was withdrawn due to slow recruitment and the study was terminated. Ten participants were randomised to the intravenous immunoglobulin group, and eight to the placebo group, and all 18 participants were included in the analysis. At 12 months after randomisation, 9 participants [50%; intravenous immunoglobulin n = 5 (50%), placebo n = 4 (50%)] made good recovery and 5 participants [28%; intravenous immunoglobulin n = 3 (30%), placebo n = 2 (25%)] made a poor recovery. Three participants in the placebo group (43%) experienced a total of 10 serious adverse events compared with none in the intravenous immunoglobulin group but none of the adverse events were judged to be related to the study treatment. No deaths occurred during the study period. Conclusion ImmunoglobuliN in the Treatment of Encephalitis (IgNiTE) was halted prematurely due to slow recruitment. Given the small sample size, the study was underpowered to evaluate the effect of intravenous immunoglobulin when compared with placebo in childhood encephalitis. The study findings, albeit from a small sample size, support existing evidence that encephalitis results in poor neurological outcomes for many children. Lessons learned from the ImmunoglobuliN in the Treatment of Encephalitis trial would be valuable for the success of future trials set up to address the efficacy of early treatment with intravenous immunoglobulin in all-cause encephalitis in children. Study limitations and future work The study was underpowered to evaluate the efficacy of intravenous immunoglobulin in the treatment of childhood encephalitis due to the small sample size achieved. Future trials should seek to address this important question. Trial registration This trial is registered as Clinical Trials.gov (NCT02308982) and ISRCTN15791925. Funding This award was funded by the National Institute for Health and Care Research (NIHR) Efficacy and Mechanism Evaluation (EME) programme (NIHR award ref: 12/212/15) and is published in full in Efficacy and Mechanism Evaluation; Vol. 11, No. 6. See the NIHR Funding and Awards website for further award information.
Decision to self-isolate during the COVID-19 pandemic in the UK: a rapid scoping review.
OBJECTIVE: Testing for COVID-19 was a key component of the UK's response to the COVID-19 pandemic. This strategy relied on positive individuals self-isolating to reduce transmission, making isolation the lynchpin in the public health approach. Therefore, we scoped evidence to systematically identify and categorise barriers and facilitators to compliance with self-isolation guidance during the COVID-19 pandemic in the UK, to inform public health strategies in future pandemics. DESIGN: A rapid scoping review was conducted. SEARCH STRATEGY: Key terms were used to search literature databases (PubMed, Scopus and the WHO COVID-19 Research Database, on 7 November 2022), Google Scholar and stakeholder-identified manuscripts, ultimately including evidence published in English from UK-based studies conducted between 2020 and 2022. DATA EXTRACTION AND SYNTHESIS: Data were extracted and synthesised into themes, organised broadly into capability, opportunity and motivation, and reviewed with key stakeholders from the UK Health Security Agency (UKHSA). RESULTS: We included 105 sources, with 63 identified from UKHSA and used to inform their decision-making during the pandemic. Influences on the decision to comply with isolation guidance were categorised into six themes: perceived ability to isolate; information and guidance; logistics; social influences, including trust; perceived value; and perceived consequences. Individuals continuously assessed these factors in deciding whether or not to comply with guidance and self-isolate. CONCLUSIONS: Decisions to self-isolate after a positive test were influenced by multiple factors, including individuals' beliefs, concerns, priorities and personal circumstances. Future testing strategies must facilitate meaningful financial, practical and mental health support to allow individuals to overcome the perceived and actual negative consequences of isolating. Clear, consistent communication of the purpose and procedures of isolating will also be critical to support compliance with self-isolation guidance, and should leverage people's perceived value in protecting others. Building public trust is also essential, but requires investment before the next pandemic starts.
A Genome-Wide Association Study of Respiratory Syncytial Virus Infection Severity in Infants.
BACKGROUND: Respiratory syncytial virus (RSV) is a significant cause of infant morbidity and mortality worldwide. Most children experience at least one 1 RSV infection by the age of two 2 years, but not all develop severe disease. However, the understanding of genetic risk factors for severe RSV is incomplete. Consequently, we conducted a genome-wide association study of RSV severity. METHODS: Disease severity was assessed by the ReSVinet scale, in a cohort of 251 infants aged 1 week to 1 year. Genotyping data were collected from multiple European study sites as part of the RESCEU Consortium. Linear regression models were used to assess the impact of genotype on RSV severity and gene expression as measured by microarray. RESULTS: While no SNPs reached the genome-wide statistical significance threshold (P < 5 × 10-8), we identified 816 candidate SNPs with a P-value of <1 × 10-4. Functional annotation of candidate SNPs highlighted genes relevant to neutrophil trafficking and cytoskeletal functions, including LSP1 and RAB27A. Moreover, SNPs within the RAB27A locus significantly altered gene expression (false discovery rate, FDR P < .05). CONCLUSIONS: These findings may provide insights into genetic mechanisms driving severe RSV infection, offering biologically relevant information for future investigations.
Differential occupational risks to healthcare workers from SARS-CoV-2: A prospective observational study
AbstractBackgroundPersonal protective equipment (PPE) and social distancing are designed to mitigate risk of occupational SARS-CoV-2 infection in hospitals. Why healthcare workers nevertheless remain at increased risk is uncertain.MethodsWe conducted voluntary Covid-19 testing programmes for symptomatic and asymptomatic staff at a UK teaching hospital using nasopharyngeal PCR testing and immunoassays for IgG antibodies. A positive result by either modality determined a composite outcome. Risk-factors for Covid-19 were investigated using multivariable logistic regression.Results1083/9809(11.0%) staff had evidence of Covid-19 at some time and provided data on potential risk-factors. Staff with a confirmed household contact were at greatest risk (adjusted odds ratio [aOR] 4.63 [95%CI 3.30-6.50]). Higher rates of Covid-19 were seen in staff working in Covid-19-facing areas (21.2% vs. 8.2% elsewhere) (aOR 2.49 [2.00-3.12]). Controlling for Covid-19-facing status, risks were heterogenous across the hospital, with higher rates in acute medicine (1.50 [1.05-2.15]) and sporadic outbreaks in areas with few or no Covid-19 patients. Covid-19 intensive care unit (ICU) staff were relatively protected (0.46 [0.29-0.72]). Positive results were more likely in Black (1.61 [1.20-2.16]) and Asian (1.58 [1.34-1.86]) staff, independent of role or working location, and in porters and cleaners (1.93 [1.25-2.97]). Contact tracing around asymptomatic staff did not lead to enhanced case identification. 24% of staff/patients remained PCR-positive at ≥6 weeks post-diagnosis.ConclusionsIncreased Covid-19 risk was seen in acute medicine, among Black and Asian staff, and porters and cleaners. A bundle of PPE-related interventions protected staff in ICU.
Paediatric meningitis in the conjugate vaccine era and a novel clinical decision model to predict bacterial aetiology.
OBJECTIVES: The aims of this study were to assess aetiology and clinical characteristics in childhood meningitis, and develop clinical decision rules to distinguish bacterial meningitis from other similar clinical syndromes. METHODS: Children aged <16 years hospitalised with suspected meningitis/encephalitis were included, and prospectively recruited at 31 UK hospitals. Meningitis was defined as identification of bacteria/viruses from cerebrospinal fluid (CSF) and/or a raised CSF white blood cell count. New clinical decision rules were developed to distinguish bacterial from viral meningitis and those of alternative aetiology. RESULTS: The cohort included 3002 children (median age 2·4 months); 1101/3002 (36·7%) had meningitis, including 180 bacterial, 423 viral and 280 with no pathogen identified. Enterovirus was the most common pathogen in those aged <6 months and 10-16 years, with Neisseria meningitidis and/or Streptococcus pneumoniae commonest at age 6 months to 9 years. The Bacterial Meningitis Score had a negative predictive value of 95·3%. We developed two clinical decision rules, that could be used either before (sensitivity 82%, specificity 71%) or after lumbar puncture (sensitivity 84%, specificity 93%), to determine risk of bacterial meningitis. CONCLUSIONS: Bacterial meningitis comprised 6% of children with suspected meningitis/encephalitis. Our clinical decision rules provide potential novel approaches to assist with identifying children with bacterial meningitis. FUNDING: This study was funded by the Meningitis Research Foundation, Pfizer and the NIHR Programme Grants for Applied Research.
Effectiveness and cost-effectiveness of community-based mental health services for individuals with severe mental illness in Iran: a systematic review and meta-analysis.
BACKGROUND: Severe mental illness (SMI) imposes a substantial worldwide burden of disability, highlighting the need for comprehensive and adaptable mental health services. This study aims to assess the efficacy and cost-effectiveness of community-based mental health services (CBMHS) in reducing relapse and rehospitalization rates among individuals with SMI in Iran. METHOD: A systematic review and meta-analysis were conducted. Medline, EMBASE, ISI, SCOPUS, and ProQuest were searched until December 2022. We focused on randomized controlled trials, quasi-experimental studies, or economic studies related to individuals with SMI. Out of 127 articles, 17 were selected for a full-text review. The primary outcomes were the severity of psychopathology, rehospitalization rates, and the mental health of caregivers. We also examined community-based interventions and their impact on various outcomes. Data extraction and risk of bias assessment were performed, and critical appraisal was conducted using JBI checklists. Meta-analysis was carried out using STATA software. (PROSPERO registration. CRD42022332660). RESULT: Rehospitalization rates among patients who received CBMHS were significantly lower, with an odds ratio of 2.14 (95% CI: 1.44 to 3.19), indicating a 2.14 times lower likelihood than those who received treatment as usual. A reduction in psychopathology accompanied this, SMD: -0.31, 95% CI: -0.49 to -0.13, I2 = 40.23%). Moreover, there was a notable improvement in social skills (SMD: -0.7, 95% CI: -0.98 to -0.44, I2 = 0.00%). The burden on caregivers also decreased (SMD: -0.55, 95% CI: -0.99 to -0.1, I2 = 63.2). The Incremental Cost-Effectiveness Ratio (ICER) for QUALY was acceptable, albeit with a wide range of 613 to 8400 Dollars. CONCLUSION: CBMHS has demonstrated effectiveness and efficiency in Iran as a developing country. Additionally, it shows promise in mitigating the shortage of acute psychiatry beds. Using multiple data collection tools poses a limitation regarding data consolidation and conducting a meta-analysis.
Seroepidemiology of SARS-CoV-2 in a cohort of pregnant women and their infants in Uganda and Malawi.
BACKGROUND: Data on SARS-CoV-2 infection in pregnancy and infancy has accumulated throughout the course of the pandemic, though evidence regarding asymptomatic SARS-CoV-2 infection and adverse birth outcomes are scarce. Limited information is available from countries in sub-Saharan Africa (SSA). The pregnant woman and infant COVID in Africa study (PeriCOVID Africa) is a South-South-North partnership involving hospitals and health centres in five countries: Malawi, Uganda, Mozambique, The Gambia, and Kenya. The study leveraged data from three ongoing prospective cohort studies: Preparing for Group B Streptococcal Vaccines (GBS PREPARE), SARS-CoV-2 infection and COVID-19 in women and their infants in Kampala and Mukono (COMAC) and Pregnancy Care Integrating Translational Science Everywhere (PRECISE). In this paper we describe the seroepidemiology of SARS-CoV-2 infection in pregnant women enrolled in sites in Uganda and Malawi, and the impact of SARS-CoV-2 infection on pregnancy and infant outcomes. OUTCOME: Seroprevalence of SARS-CoV-2 antibodies in maternal blood, reported as the proportion of seropositive women by study site and wave of COVID-19 within each country. METHODS: The PeriCOVID study was a prospective mother-infant cohort study that recruited pregnant women at any gestation antenatally or on the day of delivery. Maternal and cord blood samples were tested for SARS-CoV-2 antibodies using Wantai and Euroimmune ELISA. In periCOVID Uganda and Malawi nose and throat swabs for SARS-Cov-2 RT-PCR were obtained. RESULTS: In total, 1379 women were enrolled, giving birth to 1387 infants. Overall, 63% of pregnant women had a SARS-CoV-2 positive serology. Over subsequent waves (delta and omicron), in the absence of vaccination, seropositivity rose from 20% to over 80%. The placental transfer GMR was 1.7, indicating active placental transfer of anti-spike IgG. There was no association between SARS-CoV-2 antibody positivity and adverse pregnancy or infancy outcomes.
The safety and immunogenicity of a bivalent conjugate vaccine against Salmonella enterica Typhi and Paratyphi A in healthy Indian adults: a phase 1, randomised, active-controlled, double-blind trial.
BACKGROUND: Enteric fever caused by Salmonella enterica Typhi and Salmonella Paratyphi A is an important public health problem, especially in low-income and middle-income countries with limited access to safe water and sanitation. We present results from, to our knowledge, the first ever human study of a bivalent paratyphoid A-typhoid conjugate vaccine (Sii-PTCV). METHODS: In this double-blind phase 1 study, 60 healthy Indian adults were randomly assigned (1:1) to receive a single intramuscular dose of either Sii-PTCV or typhoid conjugate vaccine (Typbar-TCV). Safety was assessed by observing solicited adverse events for 1 week, unsolicited events for 1 month, and serious adverse events (SAEs) over 6 months. Immunogenicity at 1 month and 6 months was assessed by measuring anti-capsular polysaccharide antigen Vi (anti-Vi) IgG and IgA against Salmonella Typhi and anti-lipopolysaccharide (LPS) IgG against Salmonella Paratyphi A by ELISA, and functional antibodies using serum bactericidal assay (SBA) against Salmonella Paratyphi A. This study is registered with Clinical Trial Registry-India (CTRI/2022/06/043608) and is completed. FINDINGS: 60 participants were enrolled. Of these 60 participants, 57 (95%) participants were male and three (5%) participants were female. Solicited adverse events were observed in 27 (90%) of 30 participants who received Sii-PTCV and 26 (87%) of 30 participants who received Typbar-TCV. The most common local solicited event was pain in 27 (90%) participants who received Sii-PTCV and in 23 (77%) participants who received Typbar-TCV. The most common solicited systemic event was myalgia in five (17%) participants who received Sii-PTCV, whereas four (13%) participants who received Typbar-TCV had myalgia and four (13%) had headache. No vaccine-related unsolicited adverse events or SAEs were reported. The seroconversion rates on day 29 were 96·7% (95% CI 82·8-99·9) with Sii-PTCV and 100·0% (88·4-100·0) with Typbar-TCV for anti-Vi IgG; 93·3% (77·9-99·2) with Sii-PTCV and 100·0% (88·4-100·0) with Typbar-TCV for anti-Vi IgA; 100·0% (88·4-100·0) with Sii-PTCV and 3·3% (0·1-17·2) with Typbar-TCV for anti-LPS (paratyphoid); and 93·3% (77·9-99·2) with Sii-PTCV and 0% (0·0-11·6) with Typbar-TCV for SBA titres (paratyphoid). Paratyphoid anti-LPS immune responses were sustained at day 181. INTERPRETATION: Sii-PTCV was safe and immunogenic for both typhoid and paratyphoid antigens indicating its potential for providing comprehensive protection against enteric fever. FUNDING: Serum Institute of India.
Southeast Asia initiative to combat SARS-CoV-2 variants (SEACOVARIANTS) consortium
A strong and effective COVID-19 and future pandemic responses rely on global efforts to carry out surveillance of infections and emerging SARS-CoV-2 variants and to act accordingly in real time. Many countries in Southeast Asia lack capacity to determine the potential threat of new variants, or other emerging infections. Funded by Wellcome, the Southeast Asia initiative to combat SARS-CoV-2 variants (SEACOVARIANTS) consortium aims to develop and apply a multidisciplinary research platform in Southeast Asia (SEA) for rapid assessment of the biological significance of SARS-CoV-2 variants, thereby informing coordinated local, regional and global responses to the COVID-19 pandemic. Our proposal is delivered by the Vietnam and Thailand Wellcome Africa Asia Programmes, bringing together a multidisciplinary team in Indonesia, Thailand and Vietnam with partners in Singapore, the UK and the USA. Herein we outline five work packages to deliver strengthened regional scientific capacity that can be rapidly deployed for future outbreak responses.