Interference of Monovalent, Bivalent, and Trivalent Oral Poliovirus Vaccines on Monovalent Rotavirus Vaccine Immunogenicity in Rural Bangladesh.

BACKGROUND: Trivalent oral poliovirus vaccine (OPV) is known to interfere with monovalent rotavirus vaccine (RV1) immunogenicity. The interference caused by bivalent and monovalent OPV formulations, which will be increasingly used globally in coming years, has not been examined. We conducted a post hoc analysis to assess the effect of coadministration of different OPV formulations on RV1 immunogenicity. METHODS: Healthy infants in Matlab, Bangladesh, were randomized to receive 3 doses of monovalent OPV type 1 or bivalent OPV types 1 and 3 at either 6, 8, and 10 or 6, 10, and 14 weeks of age or trivalent OPV at 6, 10, and 14 weeks of age. All infants received 2 doses of RV1 at about 6 and 10 weeks of age. Concomitant administration was defined as RV1 and OPV given on the same day; staggered administration as RV1 and OPV given ≥1 day apart. Rotavirus seroconversion was defined as a 4-fold rise in immunoglobulin A titer from before the first RV1 dose to ≥3 weeks after the second RV1 dose. RESULTS: There were no significant differences in baseline RV1 immunogenicity among the 409 infants included in the final analysis. Infants who received RV1 and OPV concomitantly, regardless of OPV formulation, were less likely to seroconvert (47%; 95% confidence interval, 39%-54%) than those who received both vaccines staggered ≥1 day (63%; 57%-70%; P < .001). For staggered administration, we found no evidence that the interval between RV1 and OPV administration affected RV1 immunogenicity. CONCLUSIONS: Coadministration of monovalent, bivalent, or trivalent OPV seems to lower RV1 immunogenicity. CLINICAL TRIALS REGISTRATION: NCT01633216.

Lassa fever research priorities: towards effective medical countermeasures by the end of the decade.

In 2016, WHO designated Lassa fever a priority disease for epidemic preparedness as part of the WHO Blueprint for Action to Prevent Epidemics. One aspect of preparedness is to promote development of effective medical countermeasures (ie, diagnostics, therapeutics, and vaccines) against Lassa fever. Diagnostic testing for Lassa fever has important limitations and key advancements are needed to ensure rapid and accurate diagnosis. Additionally, the only treatment available for Lassa fever is ribavirin, but controversy exists regarding its effectiveness. Finally, no licensed vaccines are available for the prevention and control of Lassa fever. Ongoing epidemiological and behavioural studies are also crucial in providing actionable information for medical countermeasure development, use, and effectiveness in preventing and treating Lassa fever. This Personal View provides current research priorities for development of Lassa fever medical countermeasures based on literature published primarily in the last 5 years and consensus opinion of 20 subject matter experts with broad experience in public health or the development of diagnostics, therapeutics, and vaccines for Lassa fever. These priorities provide an important framework to ensure that Lassa fever medical countermeasures are developed and readily available for use in endemic and at-risk areas by the end of the decade.

Standardized evaluation of Zika nucleic acid tests used in clinical settings and blood screening.

Early detection of Zika virus (ZIKV) transmission within geographic regions informs implementation of community mitigation measures such as vector reduction strategies, travel advisories, enhanced surveillance among pregnant women, and possible implementation of blood and organ donor screening or deferral. Standardized, comparative assessments of ZIKV assay and testing lab performance are important to develop optimal approaches to ZIKV diagnostic testing and surveillance. We conducted an expanded blinded panel study to characterize and compare the analytical performance of fifteen diagnostic and blood screening ZIKV NAT assays, including detection among single- and multiplex assays detecting ZIKV, dengue virus (DENV) and chikungunya virus (CHIKV). A 300 member blinded panel was constructed, consisting of 11 serial half-log dilutions ranging from ~104 to 10-1 genome equivalents/mL in 25 replicates each of the Tahitian Asian ZIKV isolate in ZIKV-negative human serum. Additionally, clinical samples from individuals with DENV-like syndrome or suspected ZIKV infection in Brazil were evaluated. The majority of assays demonstrated good specificity. Analytical sensitivities varied 1-2 logs, with a substantially higher limit of detection (LOD) in one outlier. Similar analytical sensitivity for ZIKV RNA detection in singleplex and multiplex assays of the Grifols and ThermoFisher tests were observed. Coefficient of Assay Efficiency (CE), calculated to characterize assays' RNA extraction and amplification efficiency, ranged from 0.13 for the Certest VIASURE multiplex and 0.75 for the Grifols multiplex assays. In general, assays using transcription mediated amplification (TMA) technology had greater CE compared to assays using conventional PCR technology. Donor screening NAT assays were significantly more sensitive than diagnostic RT-qPCR assays, primarily attributable to higher sample input volumes. However, ideal assays to maximize sensitivity and throughput may not be a viable option in all contexts, with other factors such as cost, instrumentation, and regulatory approval status influencing assay availability and selection, particularly in resource constrained settings.

An open-source molecular diagnostic platform approach for outbreak and epidemic preparedness.

BACKGROUND: Diagnostic development for outbreak pathogens has typically followed a disease-specific reactive rather than proactive response. Given the diversity of outbreak pathogens, particularly those prioritised by the World Health Organization Research and Development Blueprint, a more flexible and proactive approach to epidemic preparedness is needed to expand access to critical molecular diagnostic tests in peripheral and resource-constrained deployment settings. OBJECTIVE: New and more sustainable directives are needed to spur the development of high-quality products, particularly for epidemics more often found in low- and middle-income countries. To leverage and de-risk the development process, we present the benefits and challenges of an open-source business model for co-development of molecular diagnostic tests for decentralised settings. METHODS: We identify key outbreak pathogens that are available only for testing in high infrastructure laboratories and compare in-country installed base platforms that could be leveraged for menu expansion. Key strengths and challenges for development are highlighted for both platform and assay developers, with discussion of how to leverage and de-risk the process through an open-source development model. RESULTS: Depending on the specific partner strengths, options for partnership roles are presented. The proposed open-source business model addresses the particular challenges in the detection of outbreak- and epidemic-prone pathogens in low- and middle-income countries, reduces development and deployment risks to support outbreak response, strengthens diagnostic capacity and creates a viable market for product developers. CONCLUSION: We hope this model for a collaborative and open-source approach for molecular diagnostics serves to encourage stakeholders to consider co-development partnerships to improve outbreak preparedness and epidemic/pandemic response.

A pilot randomized trial of incentive strategies to promote HIV retesting in rural Uganda.

BACKGROUND: Retesting for HIV is critical to identifying newly-infected persons and reinforcing prevention efforts among at-risk adults. Incentives can increase one-time HIV testing, but their role in promoting retesting is unknown. We sought to test feasibility and acceptability of incentive strategies, including commitment contracts, to promote HIV retesting among at-risk adults in rural Uganda. METHODS: At-risk HIV-negative adults were enrolled in a pilot trial assessing feasibility and acceptability of incentive strategies to promote HIV retesting three months after enrollment. Participants were randomized (1:1:3) to: 1) no incentive; 2) standard cash incentive (~US$4); and 3) commitment contract: participants could voluntarily make a low- or high-value deposit that would be returned with added interest (totaling ~US$4 including the deposit) upon retesting or lost if participants failed to retest. Contracts sought to promote retesting by leveraging loss aversion and addressing present bias via pre-commitment. Outcomes included acceptability of trial enrollment, contract feasibility (proportion of participants making deposits), and HIV retesting uptake. RESULTS: Of 130 HIV-negative eligible adults, 123 (95%) enrolled and were randomized: 74 (60%) to commitment contracts, 25 (20%) to standard incentives, and 24 (20%) to no incentive. Of contract participants, 69 (93%) made deposits. Overall, 93 (76%) participants retested for HIV: uptake was highest in the standard incentive group (22/25 [88%]) and lowest in high-value contract (26/36 [72%]) and no incentive (17/24 [71%]) groups. CONCLUSION: In a randomized trial of strategies to promote HIV retesting among at-risk adults in Uganda, incentive strategies, including commitment contracts, were feasible and had high acceptability. Our findings suggest use of incentives for HIV retesting merits further comparison in a larger trial. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT:02890459.

Diagnostics for filovirus detection: impact of recent outbreaks on the diagnostic landscape.

Ebolaviruses and Marburg virus (MARV) both belong to the family Filoviridae and cause severe haemorrhagic fever in humans. Due to high mortality rates and potential for spread from rural to urban regions, they are listed on the WHO R&D blueprint of high-priority pathogens. Recent ebolavirus outbreaks in Western and Central Africa have highlighted the importance of diagnostic testing in epidemic preparedness for these pathogens and led to the rapid development of a number of commercially available benchtop and point-of-care nucleic acid amplification tests as well as serological assays and rapid diagnostic tests. Despite these advancements, challenges still remain. While products approved under emergency use licenses during outbreak periods may continue to be used post-outbreak, a lack of clarity and incentive surrounding the regulatory approval pathway during non-outbreak periods has deterred many manufacturers from seeking full approvals. Waning of funding and poor access to samples after the 2014-2016 outbreak also contributed to cessation of development once the outbreak was declared over. There is a need for tests with improved sensitivity and specificity, and assays that can use alternative sample types could reduce the need for invasive procedures and expensive equipment, making testing in field conditions more feasible. For MARV, availability of diagnostic tests is still limited, restricted to a single ELISA test and assay panels designed to differentiate between multiple pathogens. It may be helpful to extend the target product profile for ebolavirus diagnostics to include MARV, as the viruses have many overlapping characteristics.

Diagnostic applications for Lassa fever in limited-resource settings.

Lassa fever, caused by arenavirus Lassa virus (LASV), is an acute viral haemorrhagic disease that affects up to an estimated 300 000 individuals and causes up to 5000 deaths per year in West Africa. Currently available LASV diagnostic methods are difficult to operationalise in low-resource health centres and may be less sensitive to detecting all known or emerging LASV strains. To prioritise diagnostic development for LASV, we assessed the diagnostic applications for case detection, clinical management, surveillance, outbreak response, and therapeutic and vaccine development at various healthcare levels. Diagnostic development should prioritise point-of-care and near-patient diagnostics, especially those with the ability to detect all lineages of LASV, as they would allow for rapid detection in resource-limited health facilities closer to the patient.

Spatial overlap links seemingly unconnected genotype-matched TB cases in rural Uganda.

INTRODUCTION: Incomplete understanding of TB transmission dynamics in high HIV prevalence settings remains an obstacle for prevention. Understanding where transmission occurs could provide a platform for case finding and interrupting transmission. METHODS: From 2012-2015, we sought to recruit all adults starting TB treatment in a Ugandan community. Participants underwent household (HH) contact investigation, and provided names of social contacts, sites of work, healthcare and socializing, and two sputum samples. Mycobacterium tuberculosis culture-positive specimens underwent 24-loci MIRU-VNTR and spoligotyping. We sought to identify epidemiologic links between genotype-matched cases by analyzing social networks and mapping locations where cases reported spending ≥12 hours over the one-month pre-treatment. Sites of spatial overlap (≤100m) between genotype-matched cases were considered potential transmission sites. We analyzed social networks stratified by genotype clustering status, with cases linked by shared locations, and compared network density by location type between clustered vs. non-clustered cases. RESULTS: Of 173 adults with TB, 131 (76%) were enrolled, 108 provided sputum, and 84/131 (78%) were MTB culture-positive: 52% (66/131) tested HIV-positive. Of 118 adult HH contacts, 105 (89%) were screened and 3 (2.5%) diagnosed with active TB. Overall, 33 TB cases (39%) belonged to 15 distinct MTB genotype-matched clusters. Within each cluster, no cases shared a HH or reported shared non-HH contacts. In 6/15 (40%) clusters, potential epidemiologic links were identified by spatial overlap at specific locations: 5/6 involved health care settings. Genotype-clustered TB social networks had significantly greater network density based on shared clinics (p<0.001) and decreased density based on shared marketplaces (p<0.001), compared to non-clustered networks. CONCLUSIONS: In this molecular epidemiologic study, links between MTB genotype-matched cases were only identifiable via shared locations, healthcare locations in particular, rather than named contacts. This suggests most transmission is occurring between casual contacts, and emphasizes the need for improved infection control in healthcare settings in rural Africa.

Comparative effectiveness of novel nonmonetary incentives to promote HIV testing.

OBJECTIVE: To assess the comparative effectiveness of alternative incentive-based interventions to promote HIV testing among men. DESIGN: Randomized clinical trial. METHODS: We enumerated four Ugandan parishes and enrolled men at least 18 years. Participants were randomized to six groups that received incentives of varying type and amount for HIV testing at a 13-day community health campaign. Incentive types were: gain-framed (control): participants were told they would receive a prize for testing; loss-framed: participants were told they had won a prize, shown several prizes, asked to select one, then told they would lose the prize if they did not test; lotteries: those who tested had a chance to win larger prizes. Each incentive type had a low and high amount (∼US$1 and US$5/participant). The primary outcome was HIV-testing uptake at the community health campaign. RESULTS: Of 2532 participants, 1924 (76%) tested for HIV; 7.6% of those tested were HIV-positive. There was no significant difference in testing uptake in the two lottery groups (78%; P = 0.076) or two loss-framed groups (77%; P = 0.235) vs. two gain-framed groups (74%). Across incentive types, testing did not differ significantly in high-cost (76%) vs. low-cost (75%; P = 0.416) groups. Within low-cost groups, testing uptake was significantly higher in the lottery (80%) vs. gain-framed (72%; P = 0.009) group. CONCLUSION: Overall, neither offering incentives via lotteries nor framing incentives as losses resulted in significant increases in HIV testing compared with standard gain-framed incentives. However, when offering low-cost incentives to promote HIV testing, providing lottery-based rewards may be a better strategy than gain-framed incentives.

Association of Maternal Immunity with Rotavirus Vaccine Immunogenicity in Zambian Infants.

INTRODUCTION: Live attenuated oral vaccines against rotavirus (RV) have been shown to be less efficacious in children from developing countries. Reasons for this disparity are not fully understood. We assessed the role of maternal factors including breast milk RV-specific IgA, transplacentally acquired infant serum RV-specific IgG and maternal HIV status in seroconversion among Zambian infants routinely immunized with Rotarix™ (RV1). METHODS: 420 mother-child pairs were recruited at infant age 6-12 weeks in Lusaka. Clinical information and samples were collected at baseline and at one month following the second dose of RV1. Determination of breast milk RV-specific IgA and serum RV-specific IgA and IgG was done using standardized ELISA. Seroconversion was defined as a ≥ 4 fold rise in serum IgA titre from baseline to one-month post RV1 dose 2, while seropositivity of IgA was defined as serum titre ≥ 40 and antibody variables were modelled on log-base 2. Logistic regression was used to identify predictors of the odds of seroconversion. RESULTS: Baseline infant seropositivity was 25.5% (91/357). The seroconversion frequency was 60.2% (130/216). Infants who were IgA seropositive at baseline were less likely to seroconvert compared to their seronegative counterparts (P = 0.04). There was no evidence of an association between maternal HIV status and seroconversion (P = 0.25). Higher titres of breast milk rotavirus-specific IgA were associated with a lower frequency of seroconverson (Nonparametric test for trend Z = -2.84; P<0.01): a two-fold increase in breast milk RV-specific IgA titres was associated with a 22% lower odds of seroconversion (OR = 0.80; 95% CI = 0.68-0.94; P = 0.01). There was seasonal variation in baseline breast milk rotavirus-specific IgA titres, with significantly higher GMTs during the cold dry months (P = 0.01). CONCLUSION: Low immunogenicity of RV1 vaccine could be explained in part by exposure to high antibody titres in breast milk and early exposure to wild-type rotavirus infections. Potential interference of anti-RV specific IgA in breast milk and pre-vaccination serum RV specific-IgA and IgG titres with RV1 seroconversion and effectiveness requires further research.