Amplification Free Detection of SARS-CoV-2 Using Multi-valent Binding

[Image: see text] We present the development of electrochemical impedance spectroscopy (EIS)-based biosensors for sensitive detection of SARS-CoV-2 RNA using multi-valent binding. By increasing the number of probe–target binding events per target molecule, multi-valent binding is a viable strategy for improving the biosensor performance. As EIS can provide sensitive and label-free measurements of nucleic acid targets during probe–target hybridization, we used multi-valent binding to build EIS biosensors for targeting SARS-CoV-2 RNA. For developing the biosensor, we explored two different approaches including probe combinations that individually bind in a single-valent fashion and the probes that bind in a multi-valent manner on their own. While we found excellent biosensor performance using probe combinations, we also discovered unexpected signal suppression. We explained the signal suppression theoretically using inter- and intra-probe hybridizations which confirmed our experimental findings. With our best probe combination, we achieved a LOD of 182 copies/μL (303 aM) of SARS-CoV-2 RNA and used these for successful evaluation of patient samples for COVID-19 diagnostics. We were also able to show the concept of multi-valent binding with shorter probes in the second approach. Here, a 13-nt-long probe has shown the best performance during SARS-CoV-2 RNA binding. Therefore, multi-valent binding approaches using EIS have high utility for direct detection of nucleic acid targets and for point-of-care diagnostics

User acceptability of saliva and gargle samples for identifying COVID-19 positive high-risk workers and household contacts

Throughout the COVID-19 pandemic nasopharyngeal or nose and/or throat swabs (NTS) have been the primary approach for collecting patient samples for the subsequent detection of viral RNA. However, this procedure, if undertaken correctly, can be unpleasant and therefore deters individuals from providing high quality samples. To overcome these limitations other modes of sample collection have been explored. In a cohort of frontline health care workers we have compared saliva and gargle samples to gold-standard NTS. 93% of individuals preferred providing saliva or gargle samples, with little sex-dependent variation. Viral titers collected in samples were analyzed using standard methods and showed that gargle and saliva were similarly comparable for identifying COVID-19 positive individuals compared to NTS (92% sensitivity; 98% specificity). We suggest that gargle and saliva collection are viable alternatives to NTS swabs and may encourage testing to provide better disease diagnosis and population surveillance

Addressing Gaps in Immunization Rates in a Family Medicine Residency Clinic

Adult immunizations effectively reduce morbidity, mortality, and transmission rates of multiple diseases; however, outpatient providers often a struggle to convince patients to accept vaccinations. This project’s aim is to address vaccination rates in our adult population, focusing first on the influenza vaccine in year one (2016), and then on pneumococcal vaccine in year two (2017), by 1) using a strong quality improvement strategy (known as a Champion Team) and 2) implementing a clinic program consisting of provider training, improved documentation, and informative posters targeted at patients. A quality improvement strategy known as a “Champion Team” provided a strong mechanism through which we developed and implemented the interventions across both years. Specifically, the Champion Team consisted of key stakeholders (nurses, residents, physician faculty, and informatics expert) who identified, developed, and evaluated the program. Programming included an annual health care professional training session for each vaccine (early fall of 2016 and 2017 for flu, spring 2017 for pneumococcal), improved documentation strategies and nursing uptake, and informative posters in the clinic. We assayed data from our patient electronic health record to evaluate: the percentage of our patient population for whom an immunization was documented relative to the number of unique patients seen in our clinic during that time frame. This approach in year one showed a marked increase in influenza vaccination rates in our clinic. During the 2014/2015 and 2015/2016 flu seasons our clinic vaccination rates were 39.98% and 42.05% respectively. After implementation of our champion team and clinic wide program to increase rates in 2016 our vaccination rates for the 2016/2017 flu seasons was 50.88%. Pneumonia data for a full year are under analyses and will be included in this presentation. We anticipate a similar increase in rates for our pneumococcal vaccinations. Our Champion Team and clinic wide program were perceived as relatively low-effort interventions yet appeared to increase vaccinations over the course of this study. The replication of these findings across pneumonia data (pending) and, in future work, with the herpes zoster vaccine (planned for Year 3), will increase our confidence that increases in rates were attributable to these very accessible interventions