Clinical and social determinants of COVID-19 lethality and ICU admission across variant waves in the Brazilian Amazon.

Authors

Maria Gabriela Almeida Rodrigues, Patrícia Carvalho Silva Balieiro, Alexandre Vilhena Silva-Neto, Fernando Almeida-Val, Patrícia Takako Endo, Vanderson de Souza Sampaio

Published in

International journal of epidemiology. Volume 55. Issue 5. Aug 18, 2026.

Abstract

The state of Amazonas, located in the Brazilian Amazon, was disproportionately affected during the first waves of the COVID-19 pandemic.
We conducted a population-based cohort study including all confirmed COVID-19 cases (2020-2) in the state of Amazonas, located in northern Brazil, linking data from three surveillance systems with cases of influenza-like illness (ILI) and severe acute respiratory syndrome (SARS). Outcomes included death, intensive care unit (ICU) admission, and a composite severity outcome.
Among 420 819 cases, 378 142 (89.9%) had ILI and 42 677 (10.1%) had SARS. A substantial burden of severe outcomes was observed among SARS cases, with ∼25% (n = 8910/35 909) of patients admitted to the ICU, 21.1% (n = 7229/34 323) requiring invasive mechanical ventilation, and 36.7% (n = 14 971/40 837) dying. Male sex [odds ratio (OR) = 1.23; 95% confidence interval (CI): 1.15-1.31; P < .001], age of ≥70 years (OR = 13.73; 95% CI: 11.97-15.76; P < .001), Indigenous ethnicity (OR = 2.32; 95% CI: 1.85-2.91; P < .001), dyspnea (OR = 1.99; 95% CI: 1.82-2.19; P < .001), loss of smell (OR = 1.54; 95% CI: 1.31-1.81; P < .001), and comorbidities, including chronic kidney disease (OR = 1.94; 95% CI: 1.58-2.39; P < .001), chronic respiratory disease (OR = 1.38; 95% CI: 1.08-1.77; P < .05), diabetes (OR = 1.12; 95% CI: 1.03-1.22; P < .05), obesity (OR = 1.31; 95% CI: 1.13-1.51; P < .001), and immunosuppression (OR = 1.90; 95% CI: 1.48-2.44; P < .001), were independently associated with a higher risk of death. Lethality increased significantly during the Gamma wave (OR = 3.76; 95% CI: 3.34-4.24; P < .001).
The severity of COVID-19 in Amazonas was shaped by biological, structural, and viral factors, highlighting the need for equitable strengthening of the health system.

PMID:
42753720
Bibliographic data and abstract were imported from PubMed on 18 Sep 2026.

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