We compared clinical symptoms, laboratory findings, radiographic signs and 
outcomes of COVID-19 and influenza to identify unique features. Depending on the 
heterogeneity test, we used either random or fixed-effect models to analyse the 
appropriateness of the pooled results. Overall, 540 articles included in this 
study; 75,164 cases of COVID-19 (157 studies), 113,818 influenza type A (251 
studies) and 9266 influenza type B patients (47 studies) were included. Runny 
nose, dyspnoea, sore throat and rhinorrhoea were less frequent symptoms in 
COVID-19 cases (14%, 15%, 11.5% and 9.5%, respectively) in comparison to 
influenza type A (70%, 45.5%, 49% and 44.5%, respectively) and type B (74%, 33%, 
38% and 49%, respectively). Most of the patients with COVID-19 had abnormal 
chest radiology (84%, p < 0.001) in comparison to influenza type A (57%, p < 
0.001) and B (33%, p < 0.001). The incubation period in COVID-19 (6.4 days 
estimated) was longer than influenza type A (3.4 days). Likewise, the duration 
of hospitalization in COVID-19 patients (14 days) was longer than influenza type 
A (6.5 days) and influenza type B (6.7 days). Case fatality rate of hospitalized 
patients in COVID-19 (6.5%, p < 0.001), influenza type A (6%, p < 0.001) and 
influenza type B was 3%(p < 0.001). The results showed that COVID-19 and 
influenza had many differences in clinical manifestations and radiographic 
findings. Due to the lack of effective medication or vaccine for COVID-19, 
timely detection of this viral infection and distinguishing from influenza are 
very important.