Regarding the second field study for reading COVID-19 antigen RDTs, we found that all tests used and digitized using the TiraSpot app (ie, 58 negative and 30 positive) were correctly interpreted by the proposed system (Table 1, part 3), demonstrating that the system can also be applied for reading 2-band (ie, control and test) and 3-band (ie, IgG, IgM, and control) tests. Here, CD40LG is linked to COVID-19.