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Background: The COVID-19 pandemic has resulted in a need for rapid identification of infectious cases. Testing barriers have prohibited adequate screening for SARS-CoV-2, resulting in significant delays in commencement of treatment and outbreak control measures. This study aimed to generate evidence on the performance and implementation characteristics of the BD Veritor™ Plus System rapid antigen test as compared to reverse transcription polymerase chain reaction (RT-PCR) for diagnosis of SARS-CoV-2 in Kenya. Methods: This was a field test performance evaluation in adults undergoing testing for SARS-CoV-2. Recruited participants were classified as SARS-CoV-2-positive based on RT-PCR carried out on nasopharyngeal swabs. Antigen tests were performed with simultaneous RT-PCR on 272 participants, allowing estimation of sensitivity, specificity, positive and negative predictive values for the rapid antigen test. Implementation characteristics were assessed. Results: We enrolled 97 PCR negative symptomatic and 128 PCR negative asymptomatic, and 28 PCR positive symptomatic and 19 PCR positive asymptomatic participants. Compared to RT-PCR, the sensitivity of the rapid antigen test was 94% (95% confidence interval [CI] 86.6 to 100.0) while the specificity was 98% (95% CI 96 to 100). There was no association between sensitivity and symptom status, or between the cycle threshold value and sensitivity of the BD Veritor. The rapid test had a quick turnaround time, required minimal resources, and laboratory personnel conducting testing found it easier to use than RT-PCR. The relatively high sensitivity of BD Veritor may be partially attributed to shortages of RT-PCR testing materials, resulting in specimen analysis delays and potential degradation of viral genetic material. Therefore, in resource-constrained settings, rapid antigen tests may perform better than the reference RT-PCR, resulting in prompt institution of isolation and treatment measures.  Conclusion: The BD Veritor rapid antigen test’s high sensitivity should be interpreted with consideration to the challenges occasioned by RT-PCR testing in resource-constrained settings.

Objective: Small-animal positron emission tomography (PET) is a powerful preclinical imaging tool in animal model studies. The spatial resolution and sensitivity of current PET scanners developed for small-animal imaging need to be improved to increase the quantitative accuracy of preclinical animal studies. This study aimed to improve the identification capability of edge scintillator crystals of a PET detector which will enable to apply a crystal array with the same cross-section area as the active area of a photodetector for improving the detection area and thus reducing or eliminating the inter-detector gaps. Approach: PET detectors using crystal arrays with mixed lutetium yttrium orthosilicate (LYSO) and gadolinium aluminum gallium garnet (GAGG) crystals were developed and evaluated. The crystal arrays consisted of 31 × 31 array of 0.49 × 0.49 × 20 mm3 crystals; they were read out by two silicon photomultiplier arrays with pixel sizes of 2 × 2 mm2 that were placed at both ends of the crystal arrays. The second or first outermost layer of the LYSO crystals was replaced by GAGG crystals in the two crystal arrays. The two crystal types were identified using a pulse-shape discrimination technique to provide better edge crystal identification. Main results: Using the pulse shape discrimination technique, almost all (except for a few edge) crystals were resolved in the two detectors; high sensitivity was achieved by using the scintillator array and the photodetector with the same areas and achieved high resolution by using crystals with sizes equal to 0.49 × 0.49 × 20 mm3. Energy resolutions of 19.3 ± 1.8% and 18.9 ± 1.5%, depth-of-interaction resolutions of 2.02 ± 0.17 mm and 2.04 ± 0.18 mm, and timing resolutions of 1.6 ± 0.2 ns and 1.5 ± 0.2 ns were achieved by the two detectors, respectively. Significance: In summary, novel three-dimensional high-resolution PET detectors consisting of a mixture of LYSO and GAGG crystals were developed. The detectors significantly improve the detection area with the same photodetectors and thus improve the detection efficiency.

Background: Reducing the burden of neonatal sepsis requires timely identification and initiation of suitable antibiotic treatment in primary health care (PHC) settings. Countries are encouraged to adopt simplified antibiotic regimens at PHC level for treating sick young infants (SYI) with signs of possible serious bacterial infection (PSBI). As countries implements PSBI guidelines, more lessons on effective implementation strategies and outcome measurements are needed. We document pragmatic approaches used to design, measure and report implementation strategies and outcomes while adopting PSBI guidelines in Kenya. Methods: We designed implementation research using longitudinal mixed methods embedded in a continuous regular systematic learning and adoption of evidence in PHC context. We synthesized formative data to co-create with stakeholders, implementation strategies to incorporate PSBI guidelines into routine service delivery for SYIs. This was followed by quarterly monitoring for learning and feedback on the effect of implementation strategies, documented lessons learnt and track implementation outcomes. We collected endline data to measure the overall effect on service level outcomes. Results: Our findings show that by characterizing implementation strategies and linking them with implementation outcomes, help illustrate the pathway between implementation process and outcomes. Although we have demonstrated that it is feasible to implement PSBI in PHC, effective investment in continuous capacity strengthening of providers through blended approaches, efficient use of available human resources and improving efficiency of service areas for managing SYIs optimizes timely identification and management of SYI. Sustained provision of commodities for management of SYI facilitates increased uptake of services. Strengthening facility-community linkages supports adherence to scheduled visits. Enhancing caregiver’s preparedness during postnatal contacts in community or facility will facilitate effective completion of treatment. Conclusion: Careful design, definition of terms related to measurement of implementation outcomes and strategies enables ease of interpretation of findings. Using the taxonomy of implementation outcomes help frame measurement process and provides empirical evidence in a structured way to demonstrate causal relationships between implementation strategies and outcomes. Using this approach, we have illustrated that implementation of simplified antibiotic regimens for treating SYIs with PSBI in PHC settings is feasible in Kenya.