evidence: COVID-19 vs. flu: Similarities and differences [...] COVID-19 appears to be contagious for a longer time and to spread more quickly than the flu. With COVID-19, you may be more likely to experience loss of taste or smell. Severe illness is more frequent with COVID-19 than with the flu. Compared with historical flu cases, COVID-19 may cause more hospital stays and death for people age 18 and older, even those who have no other health challenges.