Reduced blood-stage malaria growth and immune correlates in humans following RH5 vaccination.

BACKGROUND: Development of an effective vaccine against the pathogenic blood-stage infection of human malaria has proved challenging, and no candidate vaccine has affected blood-stage parasitemia following controlled human malaria infection (CHMI) with blood-stage Plasmodium falciparum. METHODS: We undertook a phase I/IIa clinical trial in healthy adults in the United Kingdom of the RH5.1 recombinant protein vaccine, targeting the P. falciparum reticulocyte-binding protein homolog 5 (RH5), formulated in AS01B adjuvant. We assessed safety, immunogenicity, and efficacy against blood-stage CHMI. Trial registered at ClinicalTrials.gov, NCT02927145. FINDINGS: The RH5.1/AS01B formulation was administered using a range of RH5.1 protein vaccine doses (2, 10, and 50 µg) and was found to be safe and well tolerated. A regimen using a delayed and fractional third dose, in contrast to three doses given at monthly intervals, led to significantly improved antibody response longevity over ∼2 years of follow-up. Following primary and secondary CHMI of vaccinees with blood-stage P. falciparum, a significant reduction in parasite growth rate was observed, defining a milestone for the blood-stage malaria vaccine field. We show that growth inhibition activity measured in vitro using purified immunoglobulin G (IgG) antibody strongly correlates with in vivo reduction of the parasite growth rate and also identify other antibody feature sets by systems serology, including the plasma anti-RH5 IgA1 response, that are associated with challenge outcome. CONCLUSIONS: Our data provide a new framework to guide rational design and delivery of next-generation vaccines to protect against malaria disease. FUNDING: This study was supported by USAID, UK MRC, Wellcome Trust, NIAID, and the NIHR Oxford-BRC.

An innovative approach to increase viral hepatitis diagnoses and linkage to care using opt-out testing and an integrated care pathway in a London Emergency Department.

Therapies that halt progression of chronic hepatitis B virus (HBV) and achieve a cure for chronic hepatitis C virus (HCV) have encouraged development of innovative strategies to diagnose and link patients to care. We describe the prevalence and risk factors for HBV and HCV infections and use of an opt-out hepatitis testing and integrated linkage to care pathway in a London Emergency Department (ED). ED patients aged ≥16 years having routine blood tests from 15 February-28 March 2016 were tested for hepatitis, unless opted out. Hepatitis B surface antigen (HBsAg) and hepatitis C antibody tests (HCV-Ab, including a confirmatory hepatitis C antigen test (HCV-Ag)) were pre-selected on electronic blood test requests. Linkage to care (attending one clinic appointment) was offered to HBsAg and HCV-Ag patients (new or known-disengaged with care diagnoses). Weighted prevalence estimates and risk factors for seropositivity adjusted by demographics and survey weights were calculated using logistic regression. Hepatitis testing uptake was 56% (3,290/5,865). Overall, 26 HBsAg (10 new diagnoses) and 63 HCV-Ab patients were identified of which 32 were HCV-Ag positive (10 new diagnoses). Weighted seroprevalence of HBsAg was 0.50% (95% CI 0.3-0.8%); HCV-Ab 2.0% (95% CI 1.5-2.7%) and HCV-Ag 1.2% (95% CI 0.8-1.7%). Risk factors for infection were being male (HBsAg: aOR 4.1, 95% CI 1.5-11.3), of non-White British ethnicity (HBsAg: aOR>11) or being homeless (HCV-Ag: aOR 18.9, 95% CI 6.9-51.4). We achieved a high linkage to care uptake for HBsAg (93%) and HCV-Ag (78%) among patients who were contacted and required linkage. A pre-selected hepatitis testing ordering system facilitated a high testing uptake. New and disengaged with care diagnoses and a high HCV prevalence were identified demonstrating the potential to identify and link patients to care in this setting. Strategies connecting clinical care with community outreach services are key for improving patient linkage to care.

Universal hospital admission screening for carbapenemase-producing organisms in a low-prevalence setting.

BACKGROUND: Carbapenemase-producing Enterobacteriaceae (CPE) are an emerging threat for healthcare providers worldwide. OBJECTIVES: To determine CPE carriage rates and risk factors in an unselected hospital cohort at the time of admission. METHODS: We approached 4567 patients within 72 h of admission to provide a rectal swab and answer a questionnaire on risk factors for carriage. Rectal swabs were cultured for carbapenem-resistant organisms on chromogenic and non-chromogenic agar, and tested for carbapenemase production by PCR (Check-Direct CPE). The study was approved by the NHS Research Ethics Committee. RESULTS: Only 6 CPE were cultured from 5 (0.1%) of 4006 patients who provided a rectal swab; only 1 was cultured using non-chromogenic media. An additional 76 culture-negative rectal swabs were initially PCR positive, but none grew a carbapenem-resistant organism despite enrichment culture and only two were positive when retested several months later by Check-Direct and a second PCR assay (Cepheid GeneXpert® Carba-R). A modified Ct cut-off of <35 would have resolved these apparent false-positives. 40% of patients had a risk factor that should prompt screening and pre-emptive isolation as defined by UK CPE guidelines but only 8.1% and 20.2% of these patients had been screened and pre-emptively isolated by clinical teams, respectively. Overseas hospitalization was the only significant risk factor for CPE carriage (P < 0.001, OR 64.3, 95% CI 7.3-488.5). CONCLUSIONS: This study highlights a very low carriage rate of CPE. Hospitalization abroad is the most important risk factor to guide admission screening in this low-prevalence setting.