Not all COVID-19 pandemic waves are alike

Domingo, Pere; Pomar, Virgina; Mur, Isabel; Castellví, Ivan; Corominas, Héctor; de Benito, Natividad

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 < 0.001), had fewer comorbidities (379/852, 44.5% vs. 1237/2479, 49.9%, P = 0.007), and a shorter interval between onset of symptoms-diagnosis (median: 3 [5] vs. 4 [5] days, P < 0.001). All-cause in-hospital mortality significantly decreased both for the whole population (24/852, 2.8% vs. 218/2479, 8.8%, P < 0.001) and hospitalized patients (20/302, 6.6% vs. 206/1570, 13.1%, P = 0.012). At adjusted logistic regression analysis, predictors of in-hospital mortality were older age (per year, adjusted odds ratio [aOR] 1.079, 95% CI: 1.063-1.094), male sex (aOR 1.476, 95% CI: 1.079-2.018), having comorbidities (aOR 1.414, 95% CI: 0.934-2.141), ICU admission (aOR 3.812, 95% CI: 1.875-7.751), mechanical ventilation (aOR 2.076, 95% CI: 0.968-4.454), and COVID-19 during surge one (with respect to surge two) (aOR 2.176, CI: 95% 1.286-3.680). 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.