Immunogenicity of T cell-inducing vaccines, such as viral vectors or DNA vaccines and Bacillus Calmette-Guérin (BCG), are frequently assessed by cytokine-based approaches. While these are sensitive methods that have shown correlates of protection in various vaccine studies, they only identify a small proportion of the vaccine-specific T cell response. Responses to vaccination are likely to be heterogeneous, particularly when comparing prime and boost or assessing vaccine performance across diverse populations. Activation-induced markers (AIM) can provide a broader view of the total antigen-specific T cell response to enable a more comprehensive evaluation of vaccine immunogenicity. We tested an AIM assay for the detection of vaccine-specific CD4⁺ and CD8⁺ T cell responses in healthy UK adults vaccinated with viral vectored Ebola vaccine candidates, ChAd3-EBO-Z and MVA-EBO-Z. We used the markers, CD25, CD134 (OX40), CD274 (PDL1), and CD107a, to sensitively identify vaccine-responsive T cells. We compared the use of OX40⁺CD25⁺ and OX40⁺PDL1⁺ in CD4⁺ T cells and OX40⁺CD25⁺ and CD25⁺CD107a⁺ in CD8⁺ T cells for their sensitivity, specificity, and associations with other measures of vaccine immunogenicity. We show that activation-induced markers can be used as an additional method of demonstrating vaccine immunogenicity, providing a broader picture of the global T cell response to vaccination.

The 2014 West African outbreak of Ebola virus disease highlighted the urgent need to develop an effective Ebola vaccine. We undertook 2 phase 1 studies assessing safety and immunogenicity of the viral vector modified vaccinia Ankara virus vectored Ebola Zaire vaccine (MVA-EBO-Z), manufactured rapidly on a new duck cell line either alone or in a heterologous prime-boost regimen with recombinant chimpanzee adenovirus type 3 vectored Ebola Zaire vaccine (ChAd3-EBO-Z) followed by MVA-EBO-Z. Adult volunteers in the United Kingdom (n = 38) and Senegal (n = 40) were vaccinated and an accelerated 1-week prime-boost regimen was assessed in Senegal. Safety was assessed by active and passive collection of local and systemic adverse events. The standard and accelerated heterologous prime-boost regimens were well-tolerated and elicited potent cellular and humoral immunogenicity in the United Kingdom and Senegal, but vaccine-induced antibody responses were significantly lower in Senegal. Cellular immune responses measured by flow cytometry were significantly greater in African vaccinees receiving ChAd3 and MVA vaccines in the same rather than the contralateral limb. MVA biomanufactured on an immortalized duck cell line shows potential for very large-scale manufacturing with lower cost of goods. This first trial of MVA-EBO-Z in humans encourages further testing in phase 2 studies, with the 1-week prime-boost interval regimen appearing to be particularly suitable for outbreak control. NCT02451891; NCT02485912.

Malaria control strategies need to respond to geographical hotspots of transmission. Detection of hotspots depends on the sensitivity of the diagnostic tool used. We conducted cross-sectional surveys in 3 sites within Kilifi County, Kenya, that had variable transmission intensities. Rapid diagnostic test (RDT), microscopy, and polymerase chain reaction (PCR) were used to detect asymptomatic parasitemia, and hotspots were detected using the spatial scan statistic. Eight thousand five hundred eighty-one study participants were surveyed in 3 sites. There were statistically significant malaria hotspots by RDT, microscopy, and PCR for all sites except by microscopy in 1 low transmission site. Pooled data analysis of hotspots by PCR overlapped with hotspots by microscopy at a moderate setting but not at 2 lower transmission settings. However, variations in degree of overlap were noted when data were analyzed by year. Hotspots by RDT were predictive of PCR/microscopy at the moderate setting, but not at the 2 low transmission settings. We observed long-term stability of hotspots by PCR and microscopy but not RDT. Malaria control programs may consider PCR testing to guide asymptomatic malaria hotspot detection once the prevalence of infection falls.

Background: Improvements in malaria control have stalled recently and new tools are needed. The R21 vaccine is comprised of the malaria circumsporozoite protein fused to hepatitis B surface antigen (HBsAg). It forms particles that lack the excess HBsAg in the frequently tested malaria vaccine candidate, RTS,S/AS01 _B . Methods: We conducted an open-label, first-in-human, Phase Ia study evaluating safety and immunogenicity of R21 administered alone and with the saponin-based adjuvant, Matrix-M ^™ (MM). Twenty-eight healthy adults received three doses of R21 given intramuscularly 4 weeks apart. We subsequently conducted a Phase Ib randomised, controlled trial in West African adults. Findings: Vaccinations were well tolerated, and the majority of local and systemic adverse events were mild. Reactogenicity was significantly lower in Burkinabe than UK vaccinees (p<0.0001). Antibody responses increased significantly 28 days after the 2 ^nd vaccination in UK volunteers. Antibody responses to R21 in all dose groups (2μg, 10μg and 50μg) were comparable to those of 50μg RTS,S/AS01 _B in malaria-naïve adults at 28 days after final vaccination. The 10μg dose induced more durable responses, with 2-fold higher NANP-specific IgG titres at 6 months compared with the 2μg and 50μg dose groups. R21 also boosted baseline humoral responses in Burkinabe adults with well-maintained responses suggesting natural boosting. Interpretation: R21 adjuvanted with MM is safe and has comparable immunogenicity to RTS,S/AS01 _B , even when administered at a five-fold lower 10μg dose in UK and African populations. This forms the basis for efficacy testing of this vaccine which could prove to be particularly cost-effective to manufacture and deploy.

Malaria remains a substantial public health burden among young children in sub-Saharan Africa and a highly efficacious vaccine eliciting a durable immune response would be a useful tool for controlling malaria. R21 is a malaria vaccine comprising nanoparticles, formed from a circumsporozoite protein and hepatitis B surface antigen (HBsAg) fusion protein, without any unfused HBsAg, and is administered with the saponin-based Matrix-M adjuvant. This study aimed to assess the safety and immunogenicity of the malaria vaccine candidate, R21, administered with or without adjuvant Matrix-M in adults naïve to malaria infection and in healthy adults from malaria endemic areas. In this Article we report two phase 1, first-in-human trials. The first trial was a phase 1a open-label study in the UK evaluating the safety and immunogenicity of R21 administered either alone, or with 50 μg of Matrix-M. The second trial was a phase 1b randomised controlled trial in Burkina Faso. Adults had to be aged 18-50 years for enrolment in the phase 1a trial, and 18-45 years in the phase 1b trial. The phase 1a trial doses were 2 μg, 10 μg, and 50 μg R21/Matrix-M, and 50 μg R21 only. The phase 1b trial doses were 10 μg R21/Matrix-M and saline placebo. Matrix-M was always dosed at 50 μg. Phase 1b implemented block randomisation by randomisation into study groups by an independent statistician based at the University of Oxford using a randomisation code list with allocation concealment using opaque sealed envelopes. The primary objective of the phase 1a trial was to assess the safety and tolerability of R21 with and without Matrix-M. The primary objective of the phase 1b trial was to assess the safety and tolerability of R21 with Matrix-M. Both trials are registered with ClinicalTrials.gov, NCT02572388 for phase 1a and NCT02925403 for phase 1b, and are completed. Between Oct 1, 2015, and Jan 3, 2017, 31 individuals were enrolled in the phase 1a study. Six individuals were assigned to receive 2 μg R21/Matrix-M, 11 to 10 μg R21/Matrix-M, ten to 50 μg R21/Matrix-M, and four to 50 μg R21 only. Between Aug 26, 2016, and Sept 28, 2017, 13 individuals were enrolled in the phase 1b study. Eight individuals were assigned to receive 10 μg R21/Matrix-M, and five to placebo. Vaccinations were well tolerated, and most local and systemic adverse events were mild. There were no serious adverse events deemed related to vaccination. Two serious adverse events occurred. The first in the 10 μg R21/Matrix-M group was worsening of previously undisclosed or undiagnosed palindromic rheumatism and was deemed unlikely to be related to vaccination and the second in the 2 μg R21/Matrix-M was hospital admission for an unplanned excision of a pre-existing Bartholin's cyst, also unrelated to vaccination. In the phase 1a study, a total of 21 adverse events were recorded in the 2 μg R21/Matrix-M group, 103 in the 10 μg R21/Matrix-M group, 94 in the 50 μg R21/Matrix-M group, and 21 in the 50 μg R21 alone group. In the phase 1b study, twelve adverse events were recorded in the 10 μg R21/Matrix-M group and 0 in the placebo group. R21 with Matrix-M adjuvant has an acceptable safety profile. These data have formed the basis for efficacy testing of this vaccine. The European Commission Framework 7 and The European & Developing Countries Clinical Trials Partnership.

Paragonimiasis is a foodborne trematode infection of the lungs caused by Paragonimus spp., presenting clinically with similar symptoms to active tuberculosis (TB). Worldwide, an estimated 20.7 million people are infected with paragonimiasis, but relatively little epidemiological data exists for Africa. Given a recently reported case, we sought to establish whether paragonimiasis should be considered as an important differential diagnosis for human TB in The Gambia, West Africa. We developed a novel PCR-based diagnostic test for Paragonimus species known to be found in West Africa, which we used to examine archived TB negative sputum samples from a cross-sectional study of volunteers with tuberculosis-like symptoms from communities in the Western coastal region of The Gambia. Based on a “zero patient” design for detection of rare diseases, 300 anonymised AFB smear negative sputum samples, randomly selected from 25 villages, were screened for active paragonimiasis by molecular detection of Paragonimus spp. DNA. No parasite DNA was found in any of the sputa of our patient group. Despite the recent case report, we found no evidence of active paragonimiasis infection masking as TB in the Western region of The Gambia.