Infectious viral load in unvaccinated and vaccinated patients infected with SARS-CoV-2 WT, Delta and Omicron

Background Viral load (VL) is one determinant of secondary transmission of SARS-CoV-2. Emergence of variants of concerns (VOC) Alpha and Delta was ascribed, at least partly, to higher VL. Furthermore, with parts of the population vaccinated, knowledge on VL in vaccine breakthrough infections is crucial. As RNA VL is only a weak proxy for infectiousness, studies on infectious virus presence by cell culture isolation are of importance. Methods We assessed nasopharyngeal swabs of COVID-19 patients for quantitative infectious viral titres (IVT) by focus-forming assay and compared to overall virus isolation success and RNA genome copies. We assessed infectious viral titres during the first 5 symptomatic days in a total of 384 patients: unvaccinated individuals infected with pre-VOC SARS-CoV-2 (n= 118) or Delta (n= 127) and vaccine breakthrough infections with Delta (n= 121) or Omicron (n=18). Findings Correlation between RNA copy number and IVT was low for all groups. No correlation between IVTs and age or sex was seen. We observed higher RNA genome copies in pre-VOC SARS-CoV-2 compared to Delta, but significantly higher IVTs in Delta infected individuals. In vaccinated vs. unvaccinated Delta infected individuals, RNA genome copies were comparable but vaccinated individuals have significantly lower IVTs, and cleared virus faster. Vaccinated individuals with Omicron infection had comparable IVTs to Delta breakthrough infections. Interpretation Quantitative IVTs can give detailed insights into virus shedding kinetics. Vaccination was associated with lower infectious titres and faster clearance for Delta, showing that vaccination would also lower transmission risk. Omicron vaccine breakthrough infections did not show elevated IVTs compared to Delta, suggesting that other mechanisms than increase VL contribute to the high infectiousness of Omicron. Funding This work was supported by the Swiss National Science Foundation 196644, 196383, NRP (National Research Program) 78 Covid-19 Grant 198412, the Fondation Ancrage Bienfaisance du Groupe Pictet and the Fondation Privée des Hôpitaux Universitaires de Genève.

Pathways and Structures: Evaluating Systems Changes in an NSF INCLUDES Alliance

In this article, we reflect on our experience applying a framework for evaluating systems change to an evaluation of a statewide West Virginia alliance funded by the National Science Foundation (NSF) to improve the early persistence of rural, first-generation, and other underrepresented minority science, technology, engineering, and mathematics (STEM) students in their programs of study. We begin with a description of the project and then discuss the two pillars around which we have built our evaluation of this project. Next, we present the challenge we confronted (despite the utility of our two pillars) in identifying and analyzing systems change, as well as the literature we consulted as we considered how to address this difficulty. Finally, we describe the framework we applied and examine how it helped us and where we still faced quandaries. Ultimately, this reflection serves two key purposes: 1) to consider a few of the challenges of measuring changes in systems and 2) to discuss our experience applying one framework to address these issues.

PR_28 Imaging Band-edge Localization in a Silicon Coupled Microring Waveguide (0925133-PO)

Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under project number 1201308. Silicon microring resonators with resonances in the O band and C band were designed, fabricated and measured.

PR_27 Imaging Band-edge Localization in a Silicon Coupled Microring Waveguide (0925133-PO)

The band-edge localization of light in a coupled resonator optical waveguide (CROW) consisting of silicon microring resonators is studied theoretically and experimentally. Summary of a Project Outcomes report of research funded by the National Science Foundation under Project Number 0925133.

PR_29 Photon-Pair Generation using Coupled Silicon Microring Resonators (1201308-PO)

The physical principles of entangled photon-pair generation in coupled silicon microring resonators were studied theoretically and experimentally. Summary of a Project Outcomes report of research funded by the National Science Foundation under Project Number 1201308.

PR_30 Towards Programmable Optical Network Front-end Devices Using Silicon Photonics (1525090-PO)

We study how the performance and utility of high-bandwidth, energy-efficient communication networks can be improved by enabling programmability and user-defined tunability in the optical front-ends using silicon photonics. Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under Project Number 1525090 (Year 1).

PR_32 Managing Spectral Content in Optical Networks Using Silicon Photonics (1525090-Y3)

We design of compact head-end components at the transceiver level using silicon photonics to implement disaggregation for improving optical communications. We study how to use optical side channels to pass control messages without increasing the number of fibers or input/output ports. Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under Project Number 1525090 (Year 3).

PR_31 Back-to-Back Test of Reconfigurable Add-Drop Using a Silicon Photonics Microchip (1525090-Y2)

We study the design of compact head-end components at the transceiver level using silicon photonics to implement disaggregation for improving optical communications, and demonstrate novel functionality at the link level. Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under Project Number 1525090 (Year 2).

PR35 Photon Pairs Generated by PRBS Pumping of Silicon Photonic Micro-resonators (1640968-Y2)

Our sub-project focused on the development of key building blocks for microchips that are cost-effective, leverages modern micro-fabrication platforms, reduces operational complexity and improves scalability. Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under Project Number 1640968 (Year 2).

PR_34 Improved Photon-Pair Generation using Silicon Photonic Micro-resonators (1640968-Y1)

We focus on the development of key building blocks for entangled photon-pair generation using microchips that are cost-effective, compact, energy efficient and leverages modern micro-fabrication platforms such as silicon photonics. Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under Project Number 1640968 (Year 1).