SARS-CoV-2 infection in patients with inflammatory bowel disease: comparison between the first and second pandemic waves
Authors: Bezzio Cristina , Vernero Marta , Costa Stefania , Armuzzi Alessandro , Fiorino Gionata , Ardizzone Sandro , Roselli Jenny , Carparelli Sonia , Orlando Ambrogio , Caprioli Flavio Andrea , Castiglione Fabiana , Viganò Chiara , Ribaldone Davide G. , Zingone Fabiana , Monterubbianesi Rita , Imperatore Nicola , Festa Stefano , Daperno Marco , Scucchi Ludovica , Ferronato Antonio , Pastorelli Luca , Alimenti Eleonora , Balestrieri Paola , Ricci Chiara , Cappello Maria , Felice Carla , Coppini Francesca , Alvisi Patrizia , Di Luna Imma , Gerardi Viviana , Variola Angela , Mazzuoli Silvia , Lenti Marco Vincenzo , Saibeni Simone ,   the Italian Group for the Study of Inflammatory Bowel Disease (IG-IBD)’s COVID-19 Study Group, Pugliese Daniela , Furfaro Federica , Maconi Giovanni , Milla Monica , Bossa Fabrizio , Giuliano Alessandra , Piazza Nicole , Manes Gianpiero , Sartini Alessandro , Buda Andrea , Micheli Federica , Ciardo Valeria , Casella Giovanni , Viscido Angelo , Bodini Giorgia , Casini Valentina , Soriano Alessandra , Amato Arnaldo , Grossi Laurino , Onali Sara , Rottoli Matteo , Spagnuolo Rocco , Baroni Stefania , Cortelezzi Claudio , Baldoni Monia , Vernero Marta , Scaldaferri Franco , Maconi Giovanni , Guarino Alessia , Palermo Andrea , D’Incà Renata , Scribano Maria Lia , Biancone Livia , Carrozza Lucio , Ascolani Marta , Costa Francesco , Di Sabatino Antonio , Zammarchi Irene , Gottin Matteo , Conforti Francesco Simone 
Published: July 2023

Abstract
Background
In Italy, the incidence of SARS-CoV-2 infection peaked in April and November 2020, defining two pandemic waves of coronavirus disease 2019 (COVID-19). This study compared the characteristics and outcomes of patients with inflammatory bowel disease (IBD) and SARS-CoV-2 infections between pandemic waves.

Methods
Observational longitudinal study of IBD patients with SARS-CoV-2 infection. Patients with established diagnoses of IBD and of SARS-CoV-2 infection were consecutively enrolled in two periods: (i) first wave, from 1 March 2020 to 31 May 2020; and (ii) second wave, from 15 September to 15 December 2020.

Results
We enrolled 937 IBD patients (219 in the first wave, 718 in the second wave). Patients of the first wave were older (mean ± SD: 46.3 ± 16.2 vs. 44.1 ± 15.4 years, p = 0.06), more likely to have ulcerative colitis (58.0% vs. 44.4%, p < 0.001) and comorbidities (48.9% vs. 38.9%; p < 0.01), and more frequently residing in Northern Italy (73.1% vs. 46.0%, p < 0.001) than patients of the second wave. There were no significant differences between pandemic waves in sex (male: 54.3% vs. 53.3%, p = 0.82) or frequency of active IBD (44.3% vs. 39.0%, p = 0.18). The rates of negative outcomes were significantly higher in the first than second wave: pneumonia (27.8% vs. 11.7%, p < 0.001), hospital admission (27.4% vs. 9.7%, p < 0.001), ventilatory support (11.9% vs. 5.4%, p < 0.003) and death (5.5% vs. 1.8%, p < 0.007).

Conclusion
Between the first and second SARS-CoV-2 pandemic waves, demographic, clinical and geographical features of IBD patients were different as were the symptoms and outcomes of infection. These differences are likely due to the different epidemiological situations and diagnostic possibilities between the two waves.