Preface IANAD. I suggest that sniffles (rhinorrhea) as well as duration of flu like symptoms (elevated temp, cough) as differentials for your diagnosis tool.

Preface IANAD. I suggest that sniffles (rhinorrhea) as well as duration of flu like symptoms (elevated temp, cough) as differentials for your diagnosis tool. Covid-19 is marked by less rhinorrhea and longer duration illness than flu i.e. time before it is severe enough to require hospitalization. You can see the rhinorrhea in the aggregate data in Table 1 https://www.nejm.org/doi/full/10.1056/NEJMoa2002032 https://www.nejm.org/doi/full/10.1056/NEJMoa2002032 You can see the rather long illness period in Figure 2D https://www.nejm.org/doi/full/10.1056/NEJMoa2001316 https://www.nejm.org/doi/full/10.1056/NEJMoa2001316 Flu is typically 4days (3-7 according to CDC https://www.cdc.gov/flu/professionals/acip/clinical.htm https://www.cdc.gov/flu/professionals/acip/clinical.htm) whereas this illness just last and lasts (both anecdotally from the NEJM paper) Apologies if I haven't captured better refs... One other rather interesting comparison is: https://drive.google.com/file/d/1DqfSnlaW6N3GBc5YKyBOCGPfdqOsqk1G/view https://drive.google.com/file/d/1DqfSnlaW6N3GBc5YKyBOCGPfdqO... page 26. This may help also develop other differentials that your tool can use. Good luck.