evidence: Differential diagnosis - COVID-19 cannot be easily distinguished from other causes of viral respiratory infections, such as influenza, RSV, other respiratory viruses, or community-acquired pneumonia, based only on clinical grounds. [...] - The case fatality rate remains higher than seasonal influenza, especially in advanced elderly and those with multiple comorbidities transplant patients. [...] Comment: Antigen testing is now in the sensitivity range similar to influenza RIDTs. The overall sensitivity of daily antigen testing was only 47% but rose to 77% on days of fever. If people were asymptomatic, it was only 18%.