Retrospective Cohort Study of COVID-19 in Patients of the Brazilian Public Health System with SARS-CoV-2 Omicron Variant Infection

Thiago B Murari; Larissa Moraes Dos Santos Fonseca; Hernane B de B Pereira; Aloísio S Nascimento Filho; Hugo Saba; Fulvio A Scorza; Antônio-Carlos G de Almeida; Ethel L N Maciel; José F F Mendes; Tarcísio M Rocha Filho; John R David; Roberto Badaró; Bruna Aparecida Souza Machado; Marcelo A Moret

doi:10.3390/vaccines10091504

Retrospective Cohort Study of COVID-19 in Patients of the Brazilian Public Health System with SARS-CoV-2 Omicron Variant Infection

Vaccines (Basel). 2022 Sep 9;10(9):1504. doi: 10.3390/vaccines10091504.

Authors

Thiago B Murari¹, Larissa Moraes Dos Santos Fonseca^{1

2}, Hernane B de B Pereira^{1

3}, Aloísio S Nascimento Filho¹, Hugo Saba^{1

3}, Fulvio A Scorza⁴, Antônio-Carlos G de Almeida⁵, Ethel L N Maciel⁶, José F F Mendes⁷, Tarcísio M Rocha Filho⁸, John R David^{9

10}, Roberto Badaró^{1

2}, Bruna Aparecida Souza Machado^{1

2}, Marcelo A Moret^{1

3}

Affiliations

¹ Modelagem Computacional, University Center SENAI/CIMATEC, Salvador 41650-010, BA, Brazil.
² SENAI Institute of Innovation (ISI) in Health Advanced Systems, University Center SENAI/CIMATEC, Salvador 41650-010, BA, Brazil.
³ Departamento de Ciências Exatas e da Terra, Universidade do Estado da Bahia, Salvador 41150-000, BA, Brazil.
⁴ Disciplina de Neurociência, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo 04021-001, SP, Brazil.
⁵ Departamento de Engenharia de Biossistemas, Universidade Federal de São João del-Rei (UFSJ), São João del-Rei 36307-352, MG, Brazil.
⁶ Laboratório de Epidemiologia, Universidade Federal do Espírito Santo, Vitória 29075-910, ES, Brazil.
⁷ Departamento de Física and I3N, Universidade de Aveiro, 3880 Aveiro, Portugal.
⁸ International Center for Condensed Matter Physics and Instituto de Física, Universidade de Brasília, Brasília 70910-900, DF, Brazil.
⁹ Faculty of Public Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA.
¹⁰ Department of Immunology and Infectious Diseases, Harvard Medical School, Boston, MA 02115, USA.

Abstract

Several vaccines against COVID-19 are now available, based on different techniques and made by different laboratories spread around the world. With the roll out of the vaccination process in an advanced stage in many countries, the reduced risk of hospitalization due to the Omicron variant relative to the Delta variant infection, despite the higher transmission risk of Omicron, may lead to a misinterpretation of the results, as infection by Omicron is associated with a significant reduction in severe outcomes and shorter hospitalization time than the Delta variant. We compared the in-hospital mortality due to the Omicron (Jan-Mar 2022) with Gamma (Jan 2021) and Delta (Oct-Dec 2021) variants of patients in the Brazilian public health system. This study also discusses the decrease in booster vaccine effectiveness in patients hospitalized due to the Omicron variant compared with the Delta variant. Without a remodeling of vaccines for new variants, booster doses may be necessary with a shorter time interval.

Keywords: COVID-19; booster; vaccine effectiveness.

Grants and funding

This research was funded by Brazilian National Council for Scientific and Technological Development—CNPq grant numbers 306041/2021-9 (B.A.S.M.), 305842/2017-0 (T.M.R.F.), 313423/2019-9 (H.S.) and 305291/2018-1 (M.A.M.).