Not all COVID-19 pandemic waves are alike.

Abstract Objective We aimed to assess differences in patients’ profiles in the first two surges of the SARS-CoV-2 pandemic in Barcelona, Spain. Methods We prospectively collected data from all adult patients with SARS-CoV-2 infection diagnosed at the Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. All the patients were diagnosed through nasopharyngeal swab PCR. The first surge spanned from March 1 to August 13, 2020, while surge two encompasses August 14 to December 8, 2020. Results There were 2479 and 852 patients with microbiologically proved SARS-CoV-2 infection in surge one and two, respectively. Patients from surge two were significantly younger (median age: 52 [IQR: 35] vs. 59 [40] years, respectively, P 5 ] vs. 4 [ 5 ] days, P Conclusions First wave SARS-CoV-2-infected patients had a more than two-fold higher in-hospital mortality than second-wave patients. The causes are likely multifactorial.