ABSTRACT
BackgroundEvidence-based infection control strategies are needed for healthcare workers (HCWs) following high-risk exposure to SARS-CoV-2. This study evaluated the negative predictive value (NPV) of a home-based 7-day infection control strategy. MethodsHCWs advised by their Infection Control or Occupational Health officer to self-isolate due to a high-risk SARS-CoV-2 exposure were enrolled between May-September 2020. The strategy consisted of symptom-triggered nasopharyngeal SARS-CoV-2 RNA testing from day 0-6 post exposure, followed by standardized home-based nasopharyngeal swab and saliva testing on day 7. The NPV of this strategy was calculated for i) clinical COVID-19 diagnosis from day 8-14 post exposure, and for ii) asymptomatic SARS-CoV-2 detected by standardized nasopharyngeal swab and saliva specimens collected at days 9-10 and 14 post exposure. Interim results are reported in the context of a second wave threatening this essential workforce. ResultsAmong 30 HCWs enrolled to date (age 31{+/-}9 years, 24 [80.0%] female), 3 were diagnosed with COVID-19 by day 14 post exposure (secondary attack rate 10.0%), with all cases detected by the 7-day infection control strategy: NPV for subsequent clinical COVID-19 or asymptomatic SARS-CoV-2 detection by day 14 was 100.0% (95%CI: 93.1-100.0%). InterpretationAmong HCWs with high-risk exposure to SARS-CoV-2, a home-based 7-day infection control strategy may have a high NPV for subsequent COVID-19 and asymptomatic SARS-CoV-2 detection. While ongoing data collection and data sharing are needed to improve the precision of the estimated NPV, we report interim results to inform infection control strategies in light of a second wave threatening this essential workforce.
ABSTRACT
Narrow beam width, higher gain and multibeam characteristics are demanded in 5G technology. Array antennas that are utilized in the existing mobile base stations have many drawbacks when operating at upper 5G frequency bands. For example, due to the high frequency operation, the antenna elements become smaller and thus, in order to provide higher gain, more antenna elements and arrays are required, which will cause the feeding network design to be more complex. The lens antenna is one of the potential candidates to replace the current structure in mobile base station. Therefore, a negative refractive index shaped lens is proposed to provide high gain and narrow beamwidth using energy conservation and Abbe's sine principle. The aim of this study is to investigate the multibeam characteristics of a negative refractive index shaped lens in mobile base station applications. In this paper, the feed positions for the multibeam are selected on the circle from the center of the lens and the accuracy of the feed position is validated through Electromagnetic (EM) simulation. Based on the analysis performed in this study, a negative refractive index shaped lens with a smaller radius and slender lens than the conventional lens is designed, with the additional capability of performing wide-angle beam scanning.
