Epidemiological Characterization of the 2024 Brazilian Dengue Epidemic: A Multi-Source Analysis Using SINAN, SIH, and InfoDengue

Version 1.2. Supersedes v.01 (21 May 2026). Brazil recorded its largest dengue epidemic in 2024. This preprint characterises the epidemic using three national surveillance systems — SINAN individual notification records, SIH hospital admission data, and InfoDengue municipal alert data — and reports indicators verified against the primary databases. Brazil notified 10,466,079 dengue cases in 2024 (InfoDengue, dengue-specific). SINAN confirmed 6,016,263 cases, including 8,834 severe dengue and 101,426 with warning signs, with 6,338 deaths (crude case fatality 0.105%). SIH recorded 154,888 unique SUS hospital admissions under ICD-10 A90/A91, with 2,429 in-hospital deaths, mean length of stay 3.34 days, and R$78,272,472 in direct SUS reimbursement. DENV-1 was dominant (68.54% of 189,618 DENV-positive typed specimens), already down from 86.92% in 2023, while DENV-2 rose to 30.49%. DENV-3 re-emerged at 0.95% of DENV-positive specimens — a genuine signal, but too small a share to have driven the 2024 epidemic. The annual mean national Rt was 1.248; the national case-weighted Rt reached 1.262 at peak week SE12. The epidemic affected 5,548 municipalities. Corrections in this version relative to v.01: the 2024 hospitalisation figure of 247,000 was a query-scope error — a multi-year ICD-10 A90 aggregate mislabelled as a single-year figure — and is corrected to 154,888 unique admissions; the statement that Rt peaked at 1.248 in epidemiological week 8 conflated the annual mean with a weekly peak and was not reproducible from the InfoDengue model; the characterisation of DENV-3 re-emergence as a driver of the 2024 epidemic is withdrawn, together with the associated estimate of 50 million unexposed Brazilians born after 2008; abstract severity counts are corrected to 8,834 and 101,426. A conflict-of-interest declaration has been added.