Table 2.
Characteristics of enrolled patients aged 6 months-5 years with severe acute respiratory infections (SARI) among those influenza virus positive and among those vaccinated with at least one current season dose of trivalent inactivated influenza vaccine (IIV3), multicenter case-control study in nine Latin American countries, 2013 (n = 966).
| Characteristic | Test result status |
Vaccination status |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| Influenza positive |
Influenza negative |
||||||||
| n | (%) | n | (%) | p-valuea | n vaccinatedb | Total | (%) | p-valuea | |
| Overall | 246 | (25) | 720 | (75) | 458 | 966 | (47) | ||
| Country | <0.001 | <0.001 | |||||||
| Argentina | 13 | (5.3) | 33 | (4.6) | 22 | 46 | (48) | ||
| Brazil | 92 | (37) | 244 | (34) | 199 | 336 | (59) | ||
| Central America | 62 | (25) | 104 | (14) | 27 | 166 | (16) | ||
| Chile | 38 | (15) | 176 | (24) | 122 | 214 | (57) | ||
| Colombia | 18 | (7.3) | 43 | (6.0) | 26 | 61 | (43) | ||
| Paraguay | 23 | (9.3) | 120 | (17) | 62 | 143 | (43) | ||
| Demographics | |||||||||
| Gender | 0.24 | 0.37 | |||||||
| Male | 147 | (60) | 399 | (55) | 252 | 546 | (46) | ||
| Female | 99 | (40) | 321 | (45) | 206 | 420 | (49) | ||
| Age group (months) | 0.26 | <0.001 | |||||||
| 6–11 | 115 | (47) | 334 | (46) | 21 | 90 | (4.6) | ||
| 12–23 | 102 | (41) | 325 | (45) | 264 | 427 | (58) | ||
| 24–59 | 29 | (18) | 61 | (8.5) | 173 | 449 | (38) | ||
| Clinical characteristics | |||||||||
| At least one preexisting condition | 0.02 | <0.001 | |||||||
| Yes | 89 | (39) | 211 | (30) | 114 | 300 | (38) | ||
| No | 141 | (61) | 485 | (70) | 322 | 626 | (51) | ||
| Admitted to intensive care | 0.31 | 0.014 | |||||||
| Yes | 33 | (15) | 80 | (12) | 41 | 113 | (36) | ||
| No | 191 | (85) | 581 | (88) | 375 | 772 | (49) | ||
| Deceased | 0.21 | 0.82 | |||||||
| Yes | 6 | (2.9) | 10 | (1.5) | 8 | 16 | (50) | ||
| No | 204 | (97) | 646 | (98) | 401 | 850 | (47) | ||
| Days from illness onset to specimen collection | 0.18 | 0.12 | |||||||
| 0–4 | 170 | (69) | 539 | (75) | 325 | 709 | (46) | ||
| 5–7 | 68 | (28) | 166 | (23) | 124 | 234 | (53) | ||
| 8–10 | 8 | (3.2) | 15 | (2.1) | 9 | 23 | (39) | ||
| Influenza RT-PCR result | |||||||||
| Negative | 384 | 720 | (53) | ||||||
| Positive | 104 | 246 | (42) | 0.003 | |||||
| Influenza A positive | 83 | 210 | (40) | <0.001 | |||||
| A (H1N1)pdm09 | 50 | 115 | (43) | 0.049 | |||||
| A(H3N2) | 22 | 56 | (39) | 0.043 | |||||
| Influenza B positive | 21 | 36 | (58) | 0.557 | |||||
a
We compared the proportion of patients with selected characteristics between influenza positive and influenza negative patients and the proportion of vaccinated between strata of each characteristic using the chi-square statistic test or Fisher’s exact test when sample size was small.
b
Defined as having received ≥1 dose of influenza vaccine ≥14 days before illness onset.