Clinical features of COVID-19 and influenza: a comparative study on Nord Franche-Comte cluster

Abstract

Clinical descriptions about influenza-like illnesses (ILI) in COVID-19 seem non-specific. We aimed to compare the clinical features of COVID-19 and influenza. We retrospectively investigated the clinical features and outcomes of confirmed cases of COVID-19 and influenza in Nord Franche-Comté Hospital between February 26th and March 14th 2020. We used SARS-CoV-2 RT-PCR and influenza virus A/B RT-PCR in respiratory samples to confirm the diagnosis. We included 124 patients. The mean age was 59 (±19 [19-98]) years with 69% female. 70 patients with COVID-19 and 54 patients with influenza A/B. Regarding age, sex and comorbidities, no differences were found between the two groups except a lower Charlson index in COVID-19 group (2 [±2.5] vs 3 [±2.4],p = 0.003). Anosmia (53% vs 17%,p < 0.001), dysgeusia (49% vs 20%,p = 0.001), diarrhea (40% vs 20%,p = 0.021), frontal headache (26% vs 9%,p = 0.021) and bilateral cracklings sounds (24% vs 9%,p = 0.034) were statistically more frequent in COVID-19. Sputum production (52% vs 29%,p = 0.010), dyspnea (59% vs 34%,p = 0.007), sore throat (44% vs 20%,p = 0.006), conjunctival hyperhemia (30% vs 4%,p < 0.001), tearing (24% vs 6%,p = 0.004), vomiting (22% vs 3%,p = 0.001) and rhonchi sounds (17% vs 1%,p = 0.002) were more frequent with influenza infection. We described several clinical differences which can help the clinicians during the co-circulation of influenza and SARS-CoV-2.

Keywords: COVID- 19; Clinical feature; Influenza; Influenza-like-illness; SARS-CoV-2.

Fig. 1

Timeline of COVID-19 and influenza A/B after onset of illness.