False Positive Results With SARS-CoV-2 RT-PCR Tests and How to Evaluate a RT-PCR-Positive Test for the Possibility of a False Positive Result

Fine-Tuning Convolutional Neural Networks for COVID-19 Detection from Chest X-ray Images

As the COVID-19 pandemic continues to ravage the world, the use of chest X-ray (CXR) images as a complementary screening strategy to reverse transcription-polymerase chain reaction (RT-PCR) testing continues to grow owing to its routine clinical application to respiratory diseases. We performed extensive convolutional neural network (CNN) fine-tuning experiments and identified that models pretrained on larger out-of-domain datasets show an improved performance. This suggests that a priori knowledge of models from out-of-field training should also apply to X-ray images. With appropriate hyperparameters selection, we found that higher resolution images carry more clinical information, and the use of mixup in training improved the performance of the model. The experimental showed that our proposed transfer learning present state-of-the-art results. Furthermore, we evaluated the performance of our model with a small amount of downstream training data and found that the model still performed well in COVID-19 identification. We also explored the mechanism of model detection using a gradient-weighted class activation mapping (Grad-CAM) method for CXR imaging to interpret the detection of radiology images. The results helped us understand how the model detects COVID-19, which can be used to discover new visual features and assist radiologists in screening.

New-Onset Diabetes Mellitus Presenting As Diabetic Ketoacidosis in Patients With COVID-19: A Case Series

Coronavirus disease 2019 (COVID‐19), a 2020 pandemic, has been linked to another global health problem, the diabetes pandemic. Both are existing in a bi-directional association. COVID-19 has been shown to be associated with worse outcomes in those with pre-existing diabetes mellitus. Nevertheless, recent data have emerged highlighting the inter-relationship between new-onset diabetes mellitus and COVID-19. Here, we present four cases admitted to the hospital with newly diagnosed diabetes mellitus associated with COVID-19. We aim to review the available literature regarding the complex association between COVID-19 and new-onset diabetes, causative factors and triggers, treatment strategies, outcomes, and its burden on the health system in general.

SARS-CoV-2 Epidemic in the Israeli Defense Force-Lessons Learned From Our rt-PCR Screening Policy

BACKGROUND

During the SARS-CoV-2 pandemic, multiple preventative measures were used to prevent the virus from spreading in the population. The Israeli defense force deployed further means to contain the disease, including putting units in quarantine, physical distancing and using masks, gowns and disinfectants when in contact with suspected patients.

METHODS

We used reverse transcriptase-polymerase chain reaction (rt-PCR) tests to screen for patients among asymptomatic soldiers within units participating in civilian aid or in close contact with known patients, using personal protective equipment. Positive results were repeated and followed with serological testing to verify the nature of results.

RESULTS

Between April and May 2020, we screened a total of 1,453 soldiers in 13 different units. We found 11 false positive results, leading to unnecessary measures until resolution, and three true positive results (0.2%). All true positive results had unreported symptoms concomitant with SARS-CoV-2 disease. These results led to the resolution of this screening policy.

CONCLUSION

Screening asymptomatic army personnel in this setting with rt-PCR test for SARS-CoV-2 is not warranted and leads to unnecessary false positive results. Efforts should be directed at identifying symptomatic patients.