Table 1.
Demographic and clinical characteristics of enrolled patients aged 6–24 months with influenza-associated severe acute respiratory infections (SARI), by case status and vaccination status, REVELAC-i, five South American countries, 2013–2017 (n = 2389).
| Variable | Cases n = 413 n (%) |
Controls n = 1976 n (%) |
p-value* | Vaccinated Two-dose n = 611 n (%) |
Vaccinated Single n = 445 n (%) |
Unvaccinated n = 1333 n (%) |
p-value* |
|---|---|---|---|---|---|---|---|
| Country | |||||||
| Argentina | 34 (8) | 205 (10) | <0.001 | 88 (14) | 2 (0.4) | 149 (11) | <0.001 |
| Brazil | 97 (23) | 255 (13) | 119 (19) | 107 (24) | 126 (9) | ||
| Chile | 141 (34) | 877 (44) | 309 (51) | 187 (42) | 522 (39) | ||
| Colombia | 38 (9) | 97 (5) | 74 (12) | 23 (5) | 38 (3) | ||
| Paraguay | 103 (25) | 542 (27) | 21 (3) | 126 (28) | 498 (37) | ||
| Year | |||||||
| 2013 | 165 (40) | 540 (27) | <0.001 | 201 (33) | 178 (40) | 326 (24) | <0.001 |
| 2014 | 47 (11) | 327 (17) | 156 (26) | 48 (11) | 170 (13) | ||
| 2015 | 83 (20) | 505 (26) | 121 (20) | 91 (20) | 376 (28) | ||
| 2016 | 89 (22) | 343 (17) | 81 (13) | 73 (16) | 278 (21) | ||
| 2017 | 29 (7) | 261 (13) | 52 (9) | 55 (12) | 183 (14) | ||
| Gender | |||||||
| Male | 225 (54) | 1071 (46) | 0.96 | 326 (53) | 239 (54) | 731 (55) | 0.80 |
| Female | 188 (46) | 905 (54) | 285 (47) | 206 (46) | 602 (45) | ||
| ≥one chronic condition**** | 100 (25) | 527 (27) | 0.46 | 167 (30) | 86 (20) | 374 (28) | <0.001 |
| Asthma | 6 (2) | 49 (3) | 0.32 | 15 (3) | 10 (2) | 30 (3) | 0.69 |
| Diabetes | 0 (0) | 3 (0.1) | 0.98 | 1 (0.1) | 1 (0.2) | 1 (0.1) | 0.70 |
| Respiratory disease | 14 (4) | 87 (5) | 0.51 | 37 (7) | 15 (4) | 49 (4) | 0.005 |
| Cardiovascular disease | 8 (2) | 37 (2) | 1.00 | 14 (3) | 6 (2) | 25 (2) | 0.44 |
| Liver disease | 2 (0.5) | 10 (0.5) | 1.00 | 1 (0.2) | 0 (0) | 11 (1) | 0.04 |
| Renal disease | 2 (0.5) | 11 (0.6) | 1.00 | 6 (1) | 3 (0.7) | 4 (0.3) | 0.11 |
| Immune disease | 2 (0.5) | 22 (1) | 0.38 | 8 (2) | 3 (0.7) | 13 (1) | 0.43 |
| Influenza vaccination status | |||||||
| Two-dose vaccination** | 89 (22) | 522 (26) | 0.05 | – | – | ||
| Single vaccination*** | 83 (20) | 362 (18) | 0.44 | – | – | ||
| Unvaccinated | 241 (58) | 1092 (55) | 0.27 | – | – | ||
| Positive influenza case | – | – | 89 (15) | 83 (19) | 241 (18) | 0.12 | |
| Days from illness onset to specimen collection | |||||||
| 0–2 | 169 (41) | 890 (45) | 0.006 | 277 (45) | 189 (42) | 593 (44) | 0.72 |
| 3–5 | 152 (37) | 774 (39) | 229 (37) | 173 (39) | 524 (39) | ||
| 6–10 | 92 (22) | 312 (16) | 105 (17) | 83 (19) | 216 (16) | ||
| Admitted to ICU | 47 (12) | 197 (10) | 0.40 | 51 (8) | 50 (12) | 143 (11) | 0.34 |
| Deceased | 8 (2) | 20 (1) | 0.17 | 4 (0.7) | 5 (1) | 19 (1) | 0.41 |
*
X2 test. **Received two vaccine doses in current season. ***Received one vaccine dose in current season. ****Percentages exclude missing data.