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Volume 32, Number 4—April 2026
Research
Dengue Incidence, Seroprevalence, and Expansion Factors from Active Surveillance, Brazil, 2016–2021
, Morgan A. Marks, Elizabeth M. Anderson, Alejandra Esteves-Jaramillo, Germán Áñez, José A. Sousa Moreira, and Fernanda Castro Boulos
Table 1
Baseline demographics for participants enrolled in large phase 3 efficacy trial of a dengue vaccine, Brazil, 2016–2021*
| Characteristic | Vaccine recipients | Placebo recipients |
|---|---|---|
| Total participants |
10,259 |
5,976 |
| Sex | ||
| F | 5,555 (54.1) | 3,216 (53.8) |
| M |
4,704 (45.9) |
2,760 (46.2) |
| Age group, y | ||
| 2–6 | 3,337 (32.5) | 1,679 (28.1) |
| 7–17 | 3,376 (32.9) | 1,771 (29.6) |
| 18–59 |
3,546 (34.6) |
2,526 (42.3) |
| Median age, y (range) |
11 (2–59) |
14 (2–59) |
| Race | ||
| Pardo† | 7,017 (68.4) | 4,036 (67.5) |
| White | 2,410 (23.5) | 1,402 (23.5) |
| Black | 655 (6.4) | 408 (6.8) |
| Asian | 149 (1.5) | 114 (1.9) |
| Indigenous or other |
28 (0.3) |
16 (0.3) |
| Prior exposure to DENV, any serotype‡ | ||
| Y | 5,009 (48.8) | 3,041 (50.9) |
| N | 4,855 (47.3) | 2,700 (45.2) |
| Unknown or missing§ |
395 (3.9) |
235 (3.9) |
| History of yellow fever vaccination | ||
| Y | 10,259 (100) | 5,976 (100) |
| N | 0 | 0 |
*Values are no. (%) except as indicated. Participants were from the DEN-03-IB trial of a live attenuated tetravalent dengue vaccine, Butantan-DV. DENV, dengue virus. †Multiracial Brazilian. ‡Prior exposure to DENV is defined as baseline 60% virus reduction neutralization test titer to any of the 4 DENV serotypes above the assay limit of detection. §Unknown result indicates missing test result, not consented sample, or participants who were not tested for DENV-3. Missing result indicates nonconsented participants for serology testing or participants who were not tested for other reasons.
1Preliminary results from this study were presented at the American Society for Tropical Medicine and Hygiene annual meeting; November 13–17, 2024, New Orleans, Louisiana, USA.