The SARS-CoV-2 variant of concern (VOC) gamma (P.1) has increased transmissibility and resulted in elevated hospitalization and mortality rates in Brazil. We investigated the clinical course of COVID-19 caused by gamma and non-VOCs at a reference hospital in Brazil in a retrospective cohort study with nonelderly hospitalized patients from two periods, before and after the emergence of gamma. Cohort 1 included patients from both periods whose samples would be eligible for whole-genome sequencing (WGS). Cohort 2 was composed of randomly selected patients from Cohort 1 whose samples were submitted to WGS. A total of 433 patients: 259 from the first and 174 from the second period. Baseline characteristics were similar, except for a higher incidence of severe distress respiratory syndrome at admission in patients from the second period. Patients from the second period had significantly higher incidence rates of advanced respiratory support (adjusted hazard ratio [aHR]: 2.04; 95% confidence interval [CI], 1.60–2.59), invasive ventilatory support (aHR: 2.72; 95% CI: 2.05–3.62), and 28-day mortality from the onset of symptoms (aHR: 2.62; 95% CI: 1.46–4.72). A total of 86 (43 gamma and 43 nongamma) patients composed Cohort 2. Patients with confirmed gamma VOC infections had higher advanced ventilatory support and mortality rates than non–gamma-infected patients. Our study suggests that nonelderly patients hospitalized for COVID-19 in the second period (used as a proxy of gamma infection) had a more severe clinical course. This might have contributed to higher hospitalization and death rates observed in the second wave in Brazil.
Address correspondence Alexandre P. Zavascki, Infectious Diseases Service, Hospital de Clínicas de Porto Alegre, 2350 Ramiro Barcelos St., Porto Alegre, RS, 90.035-903, Brazil. E-mail address: firstname.lastname@example.org
Financial support: This study was funded by “Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul—FAPERGS” (Project numbers 20/2551-0000265-9 and 16/2551-0000242-8).
Disclosures: A. P. Z. received a research grant from Pfizer unrelated to this work. A. P. Z., A. L. B. and A. F. M. are research fellows of the National Council for Scientific and Technological Development (CNPq), Ministry of Science and Technology, Brazil.
Authors’ addresses: Alexandre P. Zavascki, Internal Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, E-mail: email@example.com. Tarsila Vieceli, Serviço de Infectologia, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil, E-mail: firstname.lastname@example.org. Priscila Lamb Wink, Fabiana Caroline Zempulski Volpato, Julia Biz Willig, Francielle Liz Monteiro, and Charles Francisco Ferreira, LABRESIS, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil, E-mails: email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, and email@example.com. Beatriz Arns, Programa de Pós-Graduação em Ciências Médicas, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, E-mail: firstname.lastname@example.org. Guilherme Oliveira Magalhães and Matheus Niches Costa, Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, E-mails: email@example.com and firstname.lastname@example.org. Andreza Francisco Martins, Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil, E-mail: email@example.com. Afonso Luís Barth, Universidade Federal do Rio Grande do Sul, Faculdade de Farmácia, Porto Alegre, Brazil, E-mail: firstname.lastname@example.org.