ABSTRACT
In every pandemic, it is critical to test as many people as possible and keep track of the number of new cases of infection. Therefore, there is a need for novel, fast and unambiguous testing methods. In this study, we designed a sandwich-type voltammetric immunosensor based on unlabeled- and labeled with a redox probe antibodies against virus spike protein for fast and ultrasensitive detection of SARS-CoV-2. The process of the preparation of the sensor layer included chemisorption of cysteamine layer and covalent anchoring of antibody specific for the S1 subunit of the S protein. The source of the voltametric signal was the antibody labeled with the redox probe, which was introduced onto biosensor surface only after the recognition of the virus. This easy-to-handle immunosensor was characterized by a wide analytical range (2.0·10-7 to 0.20 mg·L-1) and low detection limit (8.0·10-8 mg·L-1 ≡ 0.08 pg·mL-1 ≡ 4 virions·µL-1). The utility of the designed device was also evidenced by the detection of SARS-CoV-2 in the clinical samples. Moreover, the main advantage and a huge novelty of the developed device, compared to those already existing, is the moment of generating the analytical signal of the redox probe that appears only after the virus recognition. Thus, our diagnostic innovation may considerably contribute to controlling the COVID-19 pandemic. The as-developed immunosensor may well offer a novel alternative approach for viral detection that could complement or even replace the existing methods.
ABSTRACT
BACKGROUND: The COVID-19 pandemic has sped up the implementation of telehealth solutions in medicine. A few symptom checkers dedicated for COVID-19 have been described, but it remains unclear whether and how they can affect patients and health systems. OBJECTIVE: This paper demonstrates our experiences with the COVID-19 risk assessment (CRA) tool. We tried to determine who the user of the web-based COVID-19 triage app is and compare this group with patients in the infectious diseases ward's admission room to evaluate who could benefit from implementing the COVID-19 online symptom checker as a remote triage solution. METHODS: We analyzed the answers of 248,862 people interacting with an online World Health Organization-based triage tool for assessing the probability of SARS-CoV-2 infection. These users filled in an online questionnaire between April 7 and August 6, 2020. Based on the presented symptoms, risk factors, and demographics, the tool assessed whether the user's answers were suggestive of COVID-19 and recommended appropriate action. Subsequently, we compared the sociodemographic and clinical characteristics of tool users with patients admitted to the Infectious Diseases Admission Room of J. Gromkowski Hospital in Wroclaw. RESULTS: The CRA tool tended to be used by asymptomatic or oligosymptomatic individuals (171,226 [68.80%] of all users). Most users were young (162,432 [65.27%] were below 40 years of age) and without comorbidities. Only 77,645 (31.20%) of the self-assessment app users were suspected of COVID-19 based on their reported symptoms. On the contrary, most admission room patients were symptomatic-symptoms such as fever, cough, and dyspnea were prevalent in both COVID-19-positive and COVID-19-negative patients. COVID-19-suspected patients in the CRA tool group presented similar COVID-19 symptoms as those who presented to the admission room. These were cough (25,062/40,007 [62.64%] in the CRA tool group vs 138/232 [59.48%] in the admission room group), fever (23,123/40,007 [57.80%] in the CRA tool group vs 146/232 [62.93%] in the admission room group), and shortness of breath (15,157/40,007 [37.89%] in the CRA tool group vs 87/232 [37.50%] in the admission room group). CONCLUSIONS: The comparison between the symptomatology of the users interacting with the CRA tool and those visiting the admission room revealed 2 major patient groups who could have benefited from the implementation of the self-assessment app in preclinical triage settings. The primary users of the CRA tool were young, oligosymptomatic individuals looking for screening for COVID-19 and reassurance early in the COVID-19 pandemic. The other group were users presenting the typical symptoms suggestive of COVID-19 at that time. The CRA tool recognized these individuals as potentially COVID-19 positive and directed them to the proper level of care. These use cases fulfil the idea of preclinical triage; however, the accuracy and influence on health care must be examined in the clinical setting.
ABSTRACT
During the COVID-19 pandemic, we have been confronted with faces covered by surgical-like masks. This raises a question about how our brains process this kind of visual information. Thus, the aims of the current study were twofold: (1) to investigate the role of attention in the processing of different types of faces with masks, and (2) to test whether such partial information about faces is treated similarly to fully visible faces. Participants were tasked with the simple detection of self-, close-other's, and unknown faces with and without a mask; this task relies on attentional processes. Event-related potential (ERP) findings revealed a similar impact of surgical-like masks for all faces: the amplitudes of early (P100) and late (P300, LPP) attention-related components were higher for faces with masks than for fully visible faces. Amplitudes of N170 were similar for covered and fully visible faces, and sources of brain activity were located in the fusiform gyri in both cases. Linear Discriminant Analysis (LDA) revealed that irrespective of whether the algorithm was trained to discriminate three types of faces either with or without masks, it was able to effectively discriminate faces that were not presented in the training phase.