Rethinking Densely Connected Convolutional Networks for Diagnosing Infectious Diseases

Due to its high transmissibility, the COVID-19 pandemic has placed an unprecedented burden on healthcare systems worldwide. X-ray imaging of the chest has emerged as a valuable and cost-effective tool for detecting and diagnosing COVID-19 patients. In this study, we developed a deep learning model using transfer learning with optimized DenseNet-169 and DenseNet-201 models for three-class classification, utilizing the Nadam optimizer. We modified the traditional DenseNet architecture and tuned the hyperparameters to improve the model's performance. The model was evaluated on a novel dataset of 3312 X-ray images from publicly available datasets, using metrics such as accuracy, recall, precision, F1-score, and the area under the receiver operating characteristics curve. Our results showed impressive detection rate accuracy and recall for COVID-19 patients, with 95.98% and 96% achieved using DenseNet-169 and 96.18% and 99% using DenseNet-201. Unique layer configurations and the Nadam optimization algorithm enabled our deep learning model to achieve high rates of accuracy not only for detecting COVID-19 patients but also for identifying normal and pneumonia-affected patients. The model's ability to detect lung problems early on, as well as its low false-positive and false-negative rates, suggest that it has the potential to serve as a reliable diagnostic tool for a variety of lung diseases.

Exposure to hand sanitisers and other cleaning products in Victoria, Australia during the COVID-19 pandemic.

BACKGROUND: In response to the COVID-19 pandemic, there was increased promotion and use of topical antiseptics (especially hand sanitisers) and cleaning products to reduce transmission of the SARS-CoV-2 virus. This study describes unintentional exposures (oral or ocular) to these substances by children during the first year (2020) of the COVID-19 pandemic compared to the previous year (2019). METHODS: This was a retrospective observational study of unintentional exposures reported to the Victorian Poisons Information Centre for the period 1 January 2019 to 31 December 2020. Substances included topical antiseptics (including hand sanitisers), bleach, multipurpose cleaners, disinfectants and high-percentage ethanol products. We analysed data for two age groups; under 5 years and 5 to 14 years. RESULTS: Oral exposures (ingestion or buccal) to topical antiseptics increased from 435 in 2019 to 882 in 2020 in the under 5 age group, with peak call numbers in 2020 coinciding with peaks in active COVID-19 daily case numbers. Oral exposures in older children (5-14 years) were lower (23 and 77 in 2019 and 2020, respectively). No children had moderate or severe symptoms at the time of the call to the Poisons Centre. Ocular exposures to topical antiseptics more than doubled from 2019 to 2020 (from 20 to 53 among children under 5 years, and 8 to 18 in older children). The majority of children with ocular exposure presented with mild symptoms; one had moderate symptoms. Changes in exposures to disinfectants, bleach and cleaners were smaller and not consistent with peaks in active COVID-19 cases. CONCLUSIONS: Unintentional oral exposures to topical disinfectants (mainly hand sanitiser) by young children increased during the COVID-19 pandemic and were more prevalent during periods of increased COVID-19 cases. While there were no cases of severe harm identified, the high number of exposures suggests that appropriate use and storage of hand sanitisers should be promoted.

The Natural Stilbenoid (-)-Hopeaphenol Inhibits Cellular Entry of SARS-CoV-2 USA-WA1/2020, B.1.1.7, and B.1.351 Variants.

Antivirals are urgently needed to combat the global SARS-CoV-2/COVID-19 pandemic, supplement existing vaccine efforts, and target emerging SARS-CoV-2 variants of concern. Small molecules that interfere with binding of the viral spike receptor binding domain (RBD) to the host angiotensin-converting enzyme II (ACE2) receptor may be effective inhibitors of SARS-CoV-2 cell entry. Here, we screened 512 pure compounds derived from natural products using a high-throughput RBD/ACE2 binding assay and identified (-)-hopeaphenol, a resveratrol tetramer, in addition to vatalbinoside A and vaticanol B, as potent and selective inhibitors of RBD/ACE2 binding and viral entry. For example, (-)-hopeaphenol disrupted RBD/ACE2 binding with a 50% inhibitory concentration (IC50) of 0.11 µM, in contrast to an IC50 of 28.3 µM against the unrelated host ligand/receptor binding pair PD-1/PD-L1 (selectivity index, 257.3). When assessed against the USA-WA1/2020 variant, (-)-hopeaphenol also inhibited entry of a VSVΔG-GFP reporter pseudovirus expressing SARS-CoV-2 spike into ACE2-expressing Vero-E6 cells and in vitro replication of infectious virus in cytopathic effect and yield reduction assays (50% effective concentrations [EC50s], 10.2 to 23.4 µM) without cytotoxicity and approaching the activities of the control antiviral remdesivir (EC50s, 1.0 to 7.3 µM). Notably, (-)-hopeaphenol also inhibited two emerging variants of concern, B.1.1.7/Alpha and B.1.351/Beta in both viral and spike-containing pseudovirus assays with similar or improved activities over the USA-WA1/2020 variant. These results identify (-)-hopeaphenol and related stilbenoid analogues as potent and selective inhibitors of viral entry across multiple SARS-CoV-2 variants of concern.

A Rare Case of Herpes Zoster in an Adult Patient Recovered From Symptomatic Reinfection of COVID-19.

In coronavirus disease 2019 (COVID-19) patients, various dermatological conditions have been observed. Varicella zoster virus (VZV) and herpes simplex virus must be ruled out before considering vesicular exanthems linked to COVID-19. The immunological status of the host has an impact on the natural history of herpes zoster (HZ). Age is a major risk factor for most of the cases of HZ. Reactivation of VZV can be triggered by iatrogenic immunosuppression or disease-related immunocompromised state or age-related immunosenescence. Rarely, dermatological symptoms have been reported in recovered COVID-19 patients. We hereby present a rare case of HZ in a recovered patient from symptomatic reinfection of COVID-19.