Beyond their substantial protection of individual vaccinees, coronavirus disease 2019 (COVID-19) vaccines might reduce viral load in breakthrough infection and thereby further suppress onward transmission. In this analysis of a real-world dataset of positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test results after inoculation with the BNT162b2 messenger RNA vaccine, we found that the viral load was substantially reduced for infections occurring 12-37 d after the first dose of vaccine. These reduced viral loads hint at a potentially lower infectiousness, further contributing to vaccine effect on virus spread.The recently authorized BNT162b2 Coronavirus Disease 2019 (COVID-19) messenger RNA (mRNA) vaccine is approximately 95% efficient in preventing polymerase chain reaction (PCR)-confirmed symptomatic disease from 7 d after the second dose and also provides some early protection starting 12 d after the first dose 1,2 . As countries race to vaccinate a substantial portion of their populations in the coming months, it is hoped that the basic reproduction number of the virus will decrease. This effect can be achieved by reducing the number of susceptible people, as well as by reducing viral load and, thereby, viral shedding of post-vaccination infections, which might render them less infectious [3][4][5][6][7] . However, the effect of vaccination on viral load in COVID-19 post-vaccination infections is currently unknown 8 .As of February 11, 2021, Maccabi Healthcare Services (MHS) in Israel has vaccinated more than 1 million of its members as part of a national rapid rollout of the vaccine. MHS member SARS-CoV-2 tests are often carried out in the MHS central laboratory, which offers the opportunity to track post-vaccination infections. In this study, we retrospectively collected and analyzed the quantitative reverse transcription PCR (RT-qPCR) test measurements of three SARS-CoV-2 genes-E, N and RdRp (Allplex 2019-nCoV assay, Seegene)-from positive post-vaccination tests performed at the MHS central laboratory between December 21, 2020, and February 11, 2021 (n = 4,938 patients, study population; Table 1). The study period was characterized by high and steady rates of positive COVID-19 tests (Extended Data Fig. 1), indicating an ongoing epidemic wave.In an analysis of the infection cycle threshold (Ct) over time, we found that the mean viral load substantially decreased 12 d after vaccination with the first vaccine dose, coinciding with the known early onset of vaccine-mediated protection 1 . When we calculated the mean Ct for post-vaccination infections identified on each day

Active control over the shape, composition, and crystalline habit of nanocrystals has long been a goal. Various methods have been shown to enable postsynthesis modification of nanoparticles, including the use of the Kirkendall effect, galvanic replacement, and cation or anion exchange, all taking advantage of enhanced solid-state diffusion on the nanoscale. In all these processes, however, alteration of the nanoparticles requires introduction of new precursor materials. Here we show that for cesium lead halide perovskite nanoparticles, a reversible structural and compositional change can be induced at room temperature solely by modification of the ligand shell composition in solution. The reversible transformation of cubic CsPbX3 nanocrystals to rhombohedral Cs4PbX6 nanocrystals is achieved by controlling the ratio of oleylamine to oleic acid capping molecules. High-resolution transmission electron microscopy investigation of Cs4PbX6 reveals the growth habit of the rhombohedral crystal structure is composed of a zero-dimensional layered network of isolated PbX6 octahedra separated by Cs cation planes. The reversible transformation between the two phases involves an exfoliation and recrystalliztion process. This scheme enables fabrication of high-purity monodispersed Cs4PbX6 nanoparticles with controlled sizes. Also, depending on the final size of the Cs4PbX6 nanoparticles as tuned by the reaction time, the back reaction yields CsPbX3 nanoplatelets with a controlled thickness. In addition, detailed surface analysis provides insight into the impact of the ligand composition on surface stabilization that, consecutively, acts as the driving force in phase and shape transformations in cesium lead halide perovskites.

Background: An Israeli national taskforce performed a multi-center clinical and analytical validation of seven serology assays to determine their utility and limitations for SARS-CoV-2 diagnosis. Methods: Serology assays from Roche, Abbott, Diasorin, BioMerieux, Beckman-Coulter, Siemens, and Mt.-Sinai ELISA were included. Negative samples from 2391 individuals representative of the Israeli population, and 698 SARS-CoV-2 PCR positive patients, collected between March and May 2020, were analyzed Findings: Immunoassays sensitivities between 81.5%-89.4% and specificities between 97.7%-100% resulted in a profound impact on the expected Positive Predictive Value (PPV) in low (<15%) prevalence scenarios. No meaningful increase was detected in the false positive rate in children compared to adults. A positive correlation between disease severity and antibody titers, and no decrease in antibody titers in the first 8 weeks after PCR positivity was observed. We identified a subgroup of symptomatic SARS-CoV-2 positive patients (~5% of patients), who remained seronegative across a wide range of antigens, isotypes, and technologies. Interpretation: wThe commercially available automated immunoassays exhibit significant differences in performance and expected PPV in low prevalence scenarios. The low false-positivity rate in under 20 0 s suggests that cross-reactive immunity from previous CoV strains is unlikely to explain the milder disease course in children. Finding no decrease in antibody titers in the first 8 weeks is in contrast to some reports of short half-life for SARS-CoV-2 antibodies. The~5% who were seronegative non-responders, using multiple

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In recent years magic angle spinning-dynamic nuclear polarization (MAS-DNP) has developed as an excellent approach for boosting the sensitivity of solid-state NMR (ssNMR) spectroscopy, thereby enabling the characterization of challenging systems in biology and chemistry. Most commonly, MAS-DNP is based on the use of nitroxide biradicals as polarizing agents. In materials science, since the use of nitroxides often limits the signal enhancement to the materials’ surface and subsurface layers, there is need for hyperpolarization approaches which will provide sensitivity in the bulk of micron sized particles. Recently, an alternative in the form of paramagnetic metal ions has emerged. Here we demonstrate the remarkable efficacy of Mn­(II) dopants, used as endogenous polarization agents for MAS-DNP, in enabling the detection of 17O at a natural abundance of only 0.038%. Distinct oxygen sites are identified in the bulk of micron-sized crystals, including battery anode materials Li4Ti5O12 (LTO) and Li2ZnTi3O8, as well as the phosphor materials NaCaPO4 and MgAl2O4, all doped with Mn­(II) ions. Density functional theory calculations are used to assign the resonances to specific oxygen environments in these phases. Depending on the Mn­(II) dopant concentration, we obtain significant signal enhancement factors, 142 and 24, for 6Li and 7Li nuclei in LTO, respectively. We furthermore follow the changes in the 6,7Li LTO resonances and determine their enhancement factors as a function of Mn­(II) concentration. The results presented show that MAS-DNP from paramagnetic metal ion dopants provides an efficient approach for probing informative nuclei such as 17O, despite their low gyromagnetic ratio and negligible abundance, without isotope enrichment.