Table 4.
Number of patients with severe acute respiratory infections per influenza test result status, crude and adjusted influenza vaccine effectiveness among children aged 6 months-5 years, REVELAC-i multicenter case-control in nine Latin American countries, 2013 (n = 966).
| Influenza type | Vaccine effectiveness |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Influenza positive |
Influenza negative |
Unadjusted |
Adjustede |
|||||||
| n vaccinated | Total | (%) | n vaccinated | total | (%) | (%) | (95%CI) | (%) | (95%CI) | |
| Influenza A and B | ||||||||||
| Any vaccine dose in 2013a | 104 | 246 | (42) | 391 | 720 | (54) | 30 | 4–49 | 30 | 1–51 |
| Unvaccinated in 2013 | Reference | Reference | ||||||||
| At least one dose in 2013b | 91 | 208 | (44) | 326 | 615 | (53) | 30 | 1–50 | 32 | −14; 47 |
| Partially vaccinatedc | 51 | 168 | (30) | 138 | 427 | (32) | 6 | −43; 39 | 0 | −68; 35 |
| Fully vaccinatedd | 45 | 162 | (28) | 210 | 499 | (42) | 46 | 17–65 | 47 | 14–71 |
| Unvaccinated in 2012 and 2013 | Reference | Reference | ||||||||
| Influenza A(H1N1)pdm09 | ||||||||||
| Any vaccine dose in 2013a | 55 | 115 | (48) | 391 | 720 | (54) | 31 | −8; 56 | 31 | −15; 59 |
| Unvaccinated in 2013 | Reference | Reference | ||||||||
| At least one dose in 2013b | 46 | 101 | (45) | 326 | 615 | (53) | 35 | −7; 60 | 35 | −30; 57 |
| Partially vaccinatedc | 23 | 78 | (29) | 138 | 427 | (32) | 3 | −76; 47 | −13 | −121; 43 |
| Fully vaccinatedd | 24 | 79 | (30) | 210 | 499 | (42) | 60 | 27–79 | 58 | 16–79 |
| Unvaccinated in 2012 and 2013 | Reference | Reference | ||||||||
| Influenza A(H3N2) | ||||||||||
| Any vaccine dose in 2013a | 21 | 56 | (37) | 391 | 720 | (54) | 20 | −46; 56 | 27 | −19; 67 |
| Unvaccinated in 2013 | Reference | Reference | ||||||||
| At least one dose in 2013b | 21 | 50 | −42 | 326 | 615 | −53 | 10 | −70; 52 | 23 | −51; 61 |
| Partially vaccinatedc | 16 | 45 | (36) | 138 | 427 | (32) | −21 | −143; 40 | 0 | −128; 52 |
| Fully vaccinatedd | 5 | 34 | (15) | 210 | 499 | (42) | 52 | −36; 83 | 65 | −9; 89 |
| Unvaccinated in 2012 and 2013 | Reference | Reference | ||||||||
| Influenza B | ||||||||||
| Any vaccine dose in 2013a | 21 | 36 | (58) | 391 | 720 | (54) | −27 | −193; 45 | ||
| Unvaccinated in 2013 | Reference | NA | ||||||||
| At least one dose in 2013b | 18 | 33 | (54) | 326 | 615 | (53) | −18 | −178; 50 | ||
| Partially vaccinatedc | 11 | 26 | (42) | 138 | 445 | (31) | NA | NA | ||
| Fully vaccinatedd | 10 | 25 | (40) | 210 | 499 | (42) | 3 | −150; 63 | NA | |
| Unvaccinated in 2012 and 2013 | Reference | Reference | ||||||||
Abbreviations: 95%CI=95% confidence interval. NA: not available, VE could not be estimated due to low sample size.
Defined as having received ≥1 dose of influenza vaccine ≥14 days before illness onset. The vaccinated group may include fully and partially vaccinated children. The reference group includes only unvaccinated in 2013 and thus may include children vaccinated in 2012. This VE estimate corresponds to the complete cases analysis based on the availability of current vaccination status and date, not on the availability of the number of doses for the current vaccination or on the prior vaccination status).
Defined as having received ≥1 dose of influenza vaccine ≥14 days before illness onset. The reference group includes only children unvaccinated in both years. This category sums up the two categories below: partially and fully vaccinated. For this complete cases analysis, subjects with missing information on vaccine doses and prior vaccination were excluded.
Defined as having received “no doses in 2012 and 1 dose in 2013”.
Defined as having received 2 doses in 2013 or 1 dose in 2013 and ≥1 dose in 2012.
Adjusted for the month of illness onset, presence of at least one preexisting condition, and age (years).