Background Aerosol transmission of COVID-19 is the subject of ongoing policy debate. Characterizing aerosol produced by people with COVID-19 is critical to understanding the role of aerosols in transmission. Objective We investigated the presence of virus in size-fractioned aerosols from six COVID-19 patients admitted into mixed acuity wards in April of 2020. Methods Size-fractionated aerosol samples and aerosol size distributions were collected from COVID-19 positive patients. Aerosol samples were analyzed for viral RNA, positive samples were cultured in Vero E6 cells. Serial RT-PCR of cells indicated samples where viral replication was likely occurring. Viral presence was also investigated by western blot and transmission electron microscopy (TEM). Results SARS-CoV-2 RNA was detected by rRT-PCR in all samples. Three samples confidently indicated the presence of viral replication, all of which were from collected sub-micron aerosol. Western blot indicated the presence of viral proteins in all but one of these samples, and intact virions were observed by TEM in one sample. Significance Observations of viral replication in the culture of submicron aerosol samples provides additional evidence that airborne transmission of COVID-19 is possible. These results support the use of efficient respiratory protection in both healthcare and by the public to limit transmission.

Liquid metal–elastomer composite is a promising soft conductor for skin-interfaced bioelectronics, soft robots, and others due to its large stretchability, ultrasoftness, high electrical conductivity, and mechanical-electrical decoupling. However, it often suffers from deformation-induced leakage, which can smear skin, deteriorate device performance, and cause circuit shorting. Besides, antimicrobial property is desirable in soft conductors to minimize microbial infections. Here, we report phase separation–based synthesis of porous liquid metal–elastomer composites with high leakage resistance and antimicrobial property, together with large stretchability, tissue-like compliance, high and stable electrical conductivity over deformation, high breathability, and magnetic resonance imaging compatibility. The porous structures can minimize leakage through damping effects and lower percolation thresholds to reduce liquid metal usage. In addition, epsilon polylysine is loaded into elastic matrices during phase separation to provide antimicrobial property. The enabled skin-interfaced bioelectronics can monitor cardiac electrical and mechanical activities and offer electrical stimulations in a mechanically imperceptible and electrically stable manner even during motions.

Following the COVID-19 outbreak, swabs for biological specimen collection were thrust to the forefront of healthcare materials. Swab sample collection and recovery are vital for reducing false negative diagnostic tests, early detection of pathogens, and harvesting DNA from limited biological samples. In this study, we report a new class of nanofiber swabs tipped with hierarchical 3D nanofiber objects produced by expanding electrospun membranes with a solids-of-revolution-inspired gas foaming technique. Nanofiber swabs significantly improve absorption and release of proteins, cells, bacteria, DNA, and viruses from solutions and surfaces. Implementation of nanofiber swabs in SARS-CoV-2 detection reduces the false negative rates at two viral concentrations and identifies SARS-CoV-2 at a 10× lower viral concentration compared to flocked and cotton swabs. The nanofiber swabs show great promise in improving test sensitivity, potentially leading to timely and accurate diagnosis of many diseases.

Strategies to control HIV-1 replication without antiviral therapy are needed to achieve a functional cure. To exploit the innate antiviral function of restriction factor cytidine deaminase APOBEC3G (A3G), we developed self-activating lentiviral vectors that efficiently deliver HIV-1 Vif-resistant mutant A3G-D128K to target cells. To circumvent APOBEC3 expression in virus-producing cells, which diminishes virus infectivity, a vector containing two overlapping fragments of A3G-D128K was designed that maintained the gene in an inactive form in the virus-producer cells. However, during transduction of target cells, retroviral recombination between the direct repeats reconstituted an active A3G-D128K in 89%–98% of transduced cells. Lentiviral vectors that expressed A3G-D128K transduced CD34+ hematopoietic stem and progenitor cells with a high efficiency (>30%). A3G-D128K expression in T cell lines CEM, CEMSS, and PM1 potently inhibited spreading infection of several HIV-1 subtypes by C-to-U deamination leading to lethal G-to-A hypermutation and inhibition of reverse transcription. SIVmac239 and HIV-2 were not inhibited, since their Vifs degraded A3G-D128K. A3G-D128K expression in CEM cells potently suppressed HIV-1 replication for >3.5 months without detectable resistant virus, suggesting a high genetic barrier for the emergence of A3G-D128K resistance. Because of this, A3G-D128K expression in HIV-1 target cells is a potential anti-HIV gene therapy approach that could be combined with other therapies for the treatment and functional cure of HIV-1 infection.

The use of protective respiratory face masks has been adopted universally as an important measure in the fight against COVID-19. Masks become contaminated by symptomatic and asymptomatic SARS-CoV-2 infected individuals and the virus can remain viable on the surface of the masks for several days. Although the regular respiratory face masks are single use disposable masks, these masks are being largely reused and not often discarded after use by the general population. Mask touching during use, reuse and disposal occurs frequently, and this can lead to increased risk of infection and further transmission. N95s and regular surgical masks were produced in which the external layers were made with nonwoven fabric impregnated with copper-oxide microparticles. The masks reduced the infectious titers of SARS-CoV-2 by more than 99.9% within 1 minute of contact, as determined by TCID50 assay and serial PCR assays. The use of masks capable of rendering the SARS-CoV-2 non-infectious within minutes, may significantly reduce the risk of viral transmission and infection.