Gunnstein Norheim

Efficacy and effectiveness of an rVSV-vectored vaccine expressing Ebola surface glycoprotein: interim results from the Guinea ring vaccination cluster-randomised trial

BACKGROUND A recombinant, replication-competent vesicular stomatitis virus-based vaccine expressing a surface glycoprotein of Zaire Ebolavirus (rVSV-ZEBOV) is a promising Ebola vaccine candidate. We report the results of an interim analysis of a trial of rVSV-ZEBOV in Guinea, west Africa. METHODS For this open-label, cluster-randomised ring vaccination trial, suspected cases of Ebola virus disease in Basse-Guinée (Guinea, west Africa) were independently ascertained by Ebola response teams as part of a national surveillance system. After laboratory confirmation of a new case, clusters of all contacts and contacts of contacts were defined and randomly allocated 1:1 to immediate vaccination or delayed (21 days later) vaccination with rVSV-ZEBOV (one dose of 2 × 10(7) plaque-forming units, administered intramuscularly in the deltoid muscle). Adults (age ≥18 years) who were not pregnant or breastfeeding were eligible for vaccination. Block randomisation was used, with randomly varying blocks, stratified by location (urban vs rural) and size of rings (≤20 vs >20 individuals). The study is open label and masking of participants and field teams to the time of vaccination is not possible, but Ebola response teams and laboratory workers were unaware of allocation to immediate or delayed vaccination. Taking into account the incubation period of the virus of about 10 days, the prespecified primary outcome was laboratory-confirmed Ebola virus disease with onset of symptoms at least 10 days after randomisation. The primary analysis was per protocol and compared the incidence of Ebola virus disease in eligible and vaccinated individuals in immediate vaccination clusters with the incidence in eligible individuals in delayed vaccination clusters. This trial is registered with the Pan African Clinical Trials Registry, number PACTR201503001057193. FINDINGS Between April 1, 2015, and July 20, 2015, 90 clusters, with a total population of 7651 people were included in the planned interim analysis. 48 of these clusters (4123 people) were randomly assigned to immediate vaccination with rVSV-ZEBOV, and 42 clusters (3528 people) were randomly assigned to delayed vaccination with rVSV-ZEBOV. In the immediate vaccination group, there were no cases of Ebola virus disease with symptom onset at least 10 days after randomisation, whereas in the delayed vaccination group there were 16 cases of Ebola virus disease from seven clusters, showing a vaccine efficacy of 100% (95% CI 74·7-100·0; p=0·0036). No new cases of Ebola virus disease were diagnosed in vaccinees from the immediate or delayed groups from 6 days post-vaccination. At the cluster level, with the inclusion of all eligible adults, vaccine effectiveness was 75·1% (95% CI -7·1 to 94·2; p=0·1791), and 76·3% (95% CI -15·5 to 95·1; p=0·3351) with the inclusion of everyone (eligible or not eligible for vaccination). 43 serious adverse events were reported; one serious adverse event was judged to be causally related to vaccination (a febrile episode in a vaccinated participant, which resolved without sequelae). Assessment of serious adverse events is ongoing. INTERPRETATION The results of this interim analysis indicate that rVSV-ZEBOV might be highly efficacious and safe in preventing Ebola virus disease, and is most likely effective at the population level when delivered during an Ebola virus disease outbreak via a ring vaccination strategy. FUNDING WHO, with support from the Wellcome Trust (UK); Médecins Sans Frontières; the Norwegian Ministry of Foreign Affairs through the Research Council of Norway; and the Canadian Government through the Public Health Agency of Canada, Canadian Institutes of Health Research, International Development Research Centre, and Department of Foreign Affairs, Trade and Development.

Efficacy and Effectiveness of an rVSV-Vectored Vaccine in Preventing Ebola Virus Disease: Final Results from the Guinea Ring Vaccination, Open-Label, Cluster-Randomised Trial (Ebola Ça Suffit!)

Summary Background rVSV-ZEBOV is a recombinant, replication competent vesicular stomatitis virus-based candidate vaccine expressing a surface glycoprotein of Zaire Ebolavirus. We tested the effect of rVSV-ZEBOV in preventing Ebola virus disease in contacts and contacts of contacts of recently confirmed cases in Guinea, west Africa. Methods We did an open-label, cluster-randomised ring vaccination trial (Ebola ça Suffit!) in the communities of Conakry and eight surrounding prefectures in the Basse-Guinée region of Guinea, and in Tomkolili and Bombali in Sierra Leone. We assessed the efficacy of a single intramuscular dose of rVSV-ZEBOV (2×107 plaque-forming units administered in the deltoid muscle) in the prevention of laboratory confirmed Ebola virus disease. After confirmation of a case of Ebola virus disease, we definitively enumerated on a list a ring (cluster) of all their contacts and contacts of contacts including named contacts and contacts of contacts who were absent at the time of the trial team visit. The list was archived, then we randomly assigned clusters (1:1) to either immediate vaccination or delayed vaccination (21 days later) of all eligible individuals (eg, those aged ≥18 years and not pregnant, breastfeeding, or severely ill). An independent statistician generated the assignment sequence using block randomisation with randomly varying blocks, stratified by location (urban vs rural) and size of rings (≤20 individuals vs >20 individuals). Ebola response teams and laboratory workers were unaware of assignments. After a recommendation by an independent data and safety monitoring board, randomisation was stopped and immediate vaccination was also offered to children aged 6–17 years and all identified rings. The prespecified primary outcome was a laboratory confirmed case of Ebola virus disease with onset 10 days or more from randomisation. The primary analysis compared the incidence of Ebola virus disease in eligible and vaccinated individuals assigned to immediate vaccination versus eligible contacts and contacts of contacts assigned to delayed vaccination. This trial is registered with the Pan African Clinical Trials Registry, number PACTR201503001057193. Findings In the randomised part of the trial we identified 4539 contacts and contacts of contacts in 51 clusters randomly assigned to immediate vaccination (of whom 3232 were eligible, 2151 consented, and 2119 were immediately vaccinated) and 4557 contacts and contacts of contacts in 47 clusters randomly assigned to delayed vaccination (of whom 3096 were eligible, 2539 consented, and 2041 were vaccinated 21 days after randomisation). No cases of Ebola virus disease occurred 10 days or more after randomisation among randomly assigned contacts and contacts of contacts vaccinated in immediate clusters versus 16 cases (7 clusters affected) among all eligible individuals in delayed clusters. Vaccine efficacy was 100% (95% CI 68·9–100·0, p=0·0045), and the calculated intraclass correlation coefficient was 0·035. Additionally, we defined 19 non-randomised clusters in which we enumerated 2745 contacts and contacts of contacts, 2006 of whom were eligible and 1677 were immediately vaccinated, including 194 children. The evidence from all 117 clusters showed that no cases of Ebola virus disease occurred 10 days or more after randomisation among all immediately vaccinated contacts and contacts of contacts versus 23 cases (11 clusters affected) among all eligible contacts and contacts of contacts in delayed plus all eligible contacts and contacts of contacts never vaccinated in immediate clusters. The estimated vaccine efficacy here was 100% (95% CI 79·3–100·0, p=0·0033). 52% of contacts and contacts of contacts assigned to immediate vaccination and in non-randomised clusters received the vaccine immediately; vaccination protected both vaccinated and unvaccinated people in those clusters. 5837 individuals in total received the vaccine (5643 adults and 194 children), and all vaccinees were followed up for 84 days. 3149 (53·9%) of 5837 individuals reported at least one adverse event in the 14 days after vaccination; these were typically mild (87·5% of all 7211 adverse events). Headache (1832 [25·4%]), fatigue (1361 [18·9%]), and muscle pain (942 [13·1%]) were the most commonly reported adverse events in this period across all age groups. 80 serious adverse events were identified, of which two were judged to be related to vaccination (one febrile reaction and one anaphylaxis) and one possibly related (influenza-like illness); all three recovered without sequelae. Interpretation The results add weight to the interim assessment that rVSV-ZEBOV offers substantial protection against Ebola virus disease, with no cases among vaccinated individuals from day 10 after vaccination in both randomised and non-randomised clusters. Funding WHO, UK Wellcome Trust, the UK Government through the Department of International Development, Médecins Sans Frontières, Norwegian Ministry of Foreign Affairs (through the Research Council of Norways GLOBVAC programme), and the Canadian Government (through the Public Health Agency of Canada, Canadian Institutes of Health Research, International Development Research Centre and Department of Foreign Affairs, Trade and Development).

Molecular Epidemiology of Neisseria meningitidis Isolated in the African Meningitis Belt between 1988 and 2003 Shows Dominance of Sequence Type 5 (ST-5) and ST-11 Complexes

ABSTRACT At the two World Health Organization Collaborating Centers for Reference and Research on Meningococci in Marseilles, France, and Oslo, Norway, the multilocus sequence typing technique was used for the characterization of a total of 357 strains of meningococci isolated from meningitis cases in 13 African countries of the meningitis belt between 1988 and 2003. Among these strains, 278 of 357 (77.9%) belonged to the sequence type 5 (ST-5) complex; 23.2% were ST-5 and 53.5% were ST-7. ST-5 was probably introduced in Africa in 1987 and was responsible for most of the meningitis cases between 1988 and 2001. ST-7 emerged in the mid-1990s and has totally replaced ST-5 since 2002. These two STs characterized serogroup A strains and have been responsible for hundreds of thousands of cases. Fifty-two strains (14.3%) belonged to the ST-11 complex. The ST-11 complex was characterized by serogroup W135, which has been responsible for an increasing number of sporadic cases since 2000 and the first W135 epidemic ever seen in Africa (in Burkina Faso in 2002). Identification of W135 ST-11 strains in many countries is a great concern for the region. Apart from these two major clonal complexes, a few other clones, such as ST-2881, ST-181, and ST-751, were sporadically detected. Careful surveys for these clones need to be conducted, but at present they play only a minor role in the overall epidemiology of meningococcal meningitis.

Evolution of extensively drug-resistant Mycobacterium tuberculosis from a susceptible ancestor in a single patient

BackgroundMycobacterium tuberculosis is characterized by a low mutation rate and a lack of genetic recombination. Yet, the rise of extensively resistant strains paints a picture of a microbe with an impressive adaptive potential. Here we describe the first documented case of extensively drug-resistant tuberculosis evolved from a susceptible ancestor within a single patient.ResultsGenome sequences of nine serial M. tuberculosis isolates from the same patient uncovered a dramatic turnover of competing lineages driven by the emergence, and subsequent fixation or loss of single nucleotide polymorphisms. For most drugs, resistance arose through independent emergence of mutations in more than one clone, of which only one ultimately prevailed as the clone carrying it expanded, displacing the other clones in the process. The vast majority of mutations identified over 3.5 years were either involved in drug resistance or hitchhiking in the genetic background of these. Additionally, RNA-sequencing of isolates grown in the absence of drug challenge revealed that the efflux-associated iniBAC operon was up-regulated over time, whereas down-regulated genes include those involved in mycolic acid synthesis.ConclusionsWe observed both rapid acquisitions of resistance to antimicrobial compounds mediated by individual mutations as well as a gradual increase in fitness in the presence of antibiotics, likely driven by stable gene expression reprogramming. The rapid turnover of resistance mutations and hitchhiking neutral mutations has major implications for inferring tuberculosis transmission events in situations where drug resistance evolves within transmission chains.

The ring vaccination trial: a novel cluster randomised controlled trial design to evaluate vaccine efficacy and effectiveness during outbreaks, with special reference to Ebola

A World Health Organization expert meeting on Ebola vaccines proposed urgent safety and efficacy studies in response to the outbreak in West Africa. One approach to communicable disease control is ring vaccination of individuals at high risk of infection due to their social or geographical connection to a known case. This paper describes the protocol for a novel cluster randomised controlled trial design which uses ring vaccination. In the Ebola ça suffit ring vaccination trial, rings are randomised 1:1 to (a) immediate vaccination of eligible adults with single dose vaccination or (b) vaccination delayed by 21 days. Vaccine efficacy against disease is assessed in participants over equivalent periods from the day of randomisation. Secondary objectives include vaccine effectiveness at the level of the ring, and incidence of serious adverse events. Ring vaccination trials are adaptive, can be run until disease elimination, allow interim analysis, and can go dormant during inter-epidemic periods.

Characterization of Neisseria meningitidis Isolates from Recent Outbreaks in Ethiopia and Comparison with Those Recovered during the Epidemic of 1988 to 1989

ABSTRACT The objectives of this study were to collect and characterize epidemic meningococcal isolates from Ethiopia from 2002 to 2003 and to compare them to 21 strains recovered during the previous large epidemic of 1988 to 1989. Ninety-five patients in all age groups with clinical signs of meningitis and a turbid cerebrospinal fluid (CSF) sample were included in the study of isolates from 2002 to 2003. Seventy-one patients (74.7%) were confirmed as having Neisseria meningitidis either by culture (n = 40) or by porA PCR (n = 31) of their CSF. The overall case fatality rate (CFR) was 11.6%; the N. meningitidis-specific CFR was 4.2%. All 40 strains were fully susceptible to all antibiotics tested except sulfonamide, were serotyped as A:4/21:P1.20,9, and belonged to sequence type 7 (ST-7). The strains from 1988 to 1989 were also equally susceptible and were characterized as A:4/21:P1.20,9, but they belonged to ST-5. Antigenic characterization of the strains revealed differences in the repertoire of lipooligosaccharides and Opa proteins between the old and the recent strains. PCR analysis of the nine lgt genes revealed the presence of the lgtAHFG genes in both old and recent strains; lgtB was present in only some of the strains, but no correlation with sequence type was observed. Further analysis showed that in addition to their pgm alleles, the Ethiopian ST-5 and ST-7 strains also differed in their tbpB, opa, fetA, and lgtA genes. The occurrence of new antigenic structures in strains sharing the same serogroup, PorA, and PorB may help explain the replacement of ST-5 by ST-7 in the African meningitis belt.

Mycobacterium tuberculosis Lineage 7 Strains Are Associated with Prolonged Patient Delay in Seeking Treatment for Pulmonary Tuberculosis in Amhara Region, Ethiopia

ABSTRACT Recent genotyping studies of Mycobacterium tuberculosis in Ethiopia have reported the identification of a new phylogenetically distinct M. tuberculosis lineage, lineage 7. We therefore investigated the genetic diversity and association of specific M. tuberculosis lineages with sociodemographic and clinical parameters among pulmonary TB patients in the Amhara Region, Ethiopia. DNA was isolated from M. tuberculosis-positive sputum specimens (n = 240) and analyzed by PCR and 24-locus mycobacterial interspersed repetitive unit–variable-number tandem-repeat (MIRU-VNTR) analysis and spoligotyping. Bioinformatic analysis assigned the M. tuberculosis genotypes to global lineages, and associations between patient characteristics and genotype were evaluated using logistic regression analysis. The study revealed a high diversity of modern and premodern M. tuberculosis lineages, among which approximately 25% were not previously reported. Among the M. tuberculosis strains (n = 138) assigned to seven subgroups, the largest cluster belonged to the lineage Central Asian (CAS) (n = 60; 26.0%), the second largest to lineage 7 (n = 36; 15.6%), and the third largest to the lineage Haarlem (n = 35; 15.2%). Four sublineages were new in the MIRU-VNTRplus database, designated NW-ETH3, NW-ETH1, NW-ETH2, and NW-ETH4, which included 24 (10.4%), 18 (7.8%), 8 (3.5%), and 5 (2.2%) isolates, respectively. Notably, patient delay in seeking treatment was significantly longer among patients infected with lineage 7 strains (Mann-Whitney test, P < 0.008) than in patients infected with CAS strains (adjusted odds ratio [AOR], 4.7; 95% confidence interval [CI], 1.6 to 13.5). Lineage 7 strains also grew more slowly than other M. tuberculosis strains. Cases of Haarlem (OR, 2.8; 95% CI, 1.2 to 6.6) and NW-ETH3 (OR, 2.8; 95% CI, 1.0 to 7.3) infection appeared in defined clusters. Intensified active case finding and contact tracing activities in the study region are needed to expedite diagnosis and treatment of TB.

An Outer Membrane Vesicle Vaccine for Prevention of Serogroup A and W‐135 Meningococcal Disease in the African Meningitis Belt

The bacterium Neisseria meningitidis of serogroups A and W‐135 has in the recent decade caused most of the cases of meningococcal meningitis in the African meningitis belt, and there is currently no efficient and affordable vaccine available demonstrated to protect against both these serogroups. Previously, deoxycholate‐extracted outer membrane vesicle (OMV) vaccines against serogroup B meningococci have been shown to be safe and induce protection in humans in clonal outbreaks. The serogroup A and W‐135 strains isolated from meningitis belt epidemics demonstrate strikingly limited variation in major surface‐exposed protein structures. We have here investigated whether the OMV vaccine strategy also can be applied to prevent both serogroups A and W‐135 meningococcal disease. A novel vaccine combining OMV extracted from recent African serogroup A and W‐135 strains and adsorbed to aluminium hydroxide was developed and its antigenic characteristics and immunogenicity were studied in mice. The specificity of the antibody responses was analysed by immunoblotting and serum bactericidal activity (SBA) assays. Moreover, the bivalent A+W‐135 vaccine was compared with monovalent A and W‐135 OMV vaccines. The bivalent OMV vaccine was able to induce similar SBA titres as the monovalent A or W‐135 OMV towards both serogroups. High SBA titres were also observed against a meningococcal serogroup C strain. These results show that subcapsular antigens may be of importance when developing broadly protective and affordable vaccines for the meningitis belt.

Preclinical immunogenicity and functional activity studies of an A+W meningococcal outer membrane vesicle (OMV) vaccine and comparisons with existing meningococcal conjugate- and polysaccharide vaccines.

Meningococci of serogroups A and W (MenA and MenW) are the main causes of epidemic bacterial meningitis outbreaks in sub-Saharan Africa. In this study we prepared a detergent extracted outer membrane vesicle (dOMV) vaccine from representative African MenA and MenW strains, and compared the immunogenicity of this vaccine with existing meningococcal conjugate and polysaccharide (PS) vaccines in mice. NMRI mice were immunized with preclinical batches of the A+W dOMV vaccine, or with commercially available vaccines; a MenA conjugate vaccine (MenAfriVac(®), Serum Institute of India), ACYW conjugate vaccine (Menveo(®), Novartis) or ACYW PS vaccine (Mencevax(®), GlaxoSmithKline). The mice received 2 doses of 1/10 or 1/50 of a human dose with a three week interval. Immune responses were tested in ELISA, serum bactericidal activity (SBA) and opsonophagocytic activity (OPA) assays. High levels of IgG antibodies against both A and W dOMV were detected in mice receiving the A+W dOMV vaccine. High SBA titers against both MenA and MenW vaccine strains were detected after only one dose of the A+W dOMV vaccine, and the titers were further increased after the second dose. The SBA and OPA titers in mice immunized with dOMV vaccine were significantly higher than in mice immunized with the ACYW-conjugate vaccine or the PS vaccine. Furthermore, the A+W dOMV vaccine was shown to induce SBA and OPA titers against MenA of the same magnitude as the titers induced by the A-conjugate vaccine. In conclusion, the A+W dOMV vaccine induced high levels of functional antibodies to both MenA and MenW strains, levels that were shown to be higher or equal to the levels induced by licensed meningococcal vaccines. Thus, an A+W dOMV vaccine could potentially serve as an alternative or a supplement to existing conjugate and PS vaccines in the African meningitis belt.

Stability of a Vesicular Stomatitis Virus–Vectored Ebola Vaccine

The live attenuated vesicular stomatitis virus-vectored Ebola vaccine rVSV-ZEBOV is currently undergoing clinical trials in West Africa. The vaccine is to be stored at -70°C or less. Since maintaining the cold chain is challenging in rural areas, the rVSV-ZEBOV vaccines short-term and long-term stability at different temperatures was examined. Different dilutions were tested since the optimal vaccine dosage had not yet been determined at the start of this experiment. The results demonstrate that the original vaccine formulation was stable for 1 week at 4°C and for 24 hours at 25°C. The stability of the vaccine was compromised by both high temperatures and dilution.