Coronavirus has become a household name over the past two years. Diagnostic tests have seemed to assist early identification and isolation of infected individuals affected by coronavirus, thereby curbing the spread of the disease. Although RT-PCR has been the gold-standard for diagnostic testing, its high turnaround time for results has led to several alternate biosensing technologies being employed for rapid Covid-19 screening. Electrochemical biosensors, being one of those technologies, has the advantage of being miniaturized for point-of-use, and producing rapid and highly sensitive results. Often, these alternate techniques involve the detection of an antigen (eg. spike protein) instead of the nucleic acid material. This leads to a compromise in the detection accuracy while improving the detection time and eliminating the need for amplification. Understanding the working principle of rapid antigen tests is essential for improving the accuracy. In this study, we shed light towards the interaction of coronavirus with our Ultra-Fast Covid-19 Diagnostic Sensor (UFC-19). UFC-19 is a nickel based electrochemical sensor that interacts with SARS-CoV-2 at very short times to produce current responses in a particular analysis window. Chronoamperometry is used for electrochemically characterizing the interaction between the electrocatalyst and hydrogen occupancies on spike protein. This reaction seems to occur at very short time span (~1 ms) as a result of local pH changes at the electrical double layer. UFC-19 can screen for coronavirus in saliva or water and can distinguish coronavirus current response from other viruses like HIV, Influenza or bacteria like E. coli. Although the response is specific to corona viruses, it is not specific to SARS-CoV-2. Hence, it is of utmost importance to selectively distinguish SARS-CoV-2 from other coronaviruses such as SARS-CoV, MERS-CoV or Human-CoV. The kinetics of these coronaviruses are studied using a rotating disk electrode to differentiate how their spike proteins diffuse and interact at the double layer causing pH change. There seems to be a correlation between the dissociation constants, pH changes and diffusion coefficients of the different corona viruses from our preliminary studies. Diffusion coefficients of these corona viruses could provide a possible insight into rate at which the interaction occurs leading a pathway for selective SARS-CoV-2 detection. This insight is key to engineer and improve the accuracy of UFC-19 for SARS-CoV-2 detection and to further extend this technology for other pathogenic organisms.