Adjusted VE in Children in the United States, by Season, as Reported by the CDC, US Influenza VE Network
| Influenza Type and Age Group . | 2017–2018 H3N2 and B/Yamagata, VE% (95% CI) . | 2018–2019 H1N1 and H3N2, VE% (95% CI) . | 2019–2020 B/Victoria and H1N1, VE% (95% CI) . |
|---|---|---|---|
| Influenza A and B | |||
| Overall all ages | 38 (31 to 43) | 29 (21 to 35) | 39 (32 to 44) |
| 6 mo to 8 y | 68 (55 to 77) | 48 (37 to 58) | 34 (19 to 46) |
| 9–17 y | 32 (16 to 44) | 7 (−20 to 28) | 40 (22 to 53) |
| Influenza A(H1N1)pdm09 | |||
| Overall all ages | 62 (50 to 71) | 44 (37 to 51) | 30 (21 to 39) |
| 6 mo to 8 y | 87 (71 to 95) | 59 (47 to 69) | 23 (−3 to 42) |
| 9–17 y | 70 (46 to 67) | 24 (−18 to 51) | 29 (−7 to 52) |
| Influenza A(H3N2) | |||
| Overall all ages | 22 (12 to 31) | 9 (−4 to 20) | NA |
| 6 mo to 8 y | 54 (33 to 69) | 24 (1 to 42) | NA |
| 9–17 y | 18 (−6 to 36) | 3 (−30 to 28) | NA |
| Influenza B/Victoria | |||
| Overall all ages | 76 (45 to 89) | Not reported | 45 (37 to 52) |
| 6 mo to 8 y | Not reported | Not reported | 39 (20 to 54) |
| 9–17 y | Note reported | Not reported | 43 (23 to 58) |
| Influenza B/Yamagata | |||
| Overall all ages | 48 (39 to 55) | Not reported | NA |
| 6 mo to 8 y | 77 (49 to 90) | Not reported | NA |
| 9–17 y | 28 (1 to 48) | Not reported | NA |
| Influenza Type and Age Group . | 2017–2018 H3N2 and B/Yamagata, VE% (95% CI) . | 2018–2019 H1N1 and H3N2, VE% (95% CI) . | 2019–2020 B/Victoria and H1N1, VE% (95% CI) . |
|---|---|---|---|
| Influenza A and B | |||
| Overall all ages | 38 (31 to 43) | 29 (21 to 35) | 39 (32 to 44) |
| 6 mo to 8 y | 68 (55 to 77) | 48 (37 to 58) | 34 (19 to 46) |
| 9–17 y | 32 (16 to 44) | 7 (−20 to 28) | 40 (22 to 53) |
| Influenza A(H1N1)pdm09 | |||
| Overall all ages | 62 (50 to 71) | 44 (37 to 51) | 30 (21 to 39) |
| 6 mo to 8 y | 87 (71 to 95) | 59 (47 to 69) | 23 (−3 to 42) |
| 9–17 y | 70 (46 to 67) | 24 (−18 to 51) | 29 (−7 to 52) |
| Influenza A(H3N2) | |||
| Overall all ages | 22 (12 to 31) | 9 (−4 to 20) | NA |
| 6 mo to 8 y | 54 (33 to 69) | 24 (1 to 42) | NA |
| 9–17 y | 18 (−6 to 36) | 3 (−30 to 28) | NA |
| Influenza B/Victoria | |||
| Overall all ages | 76 (45 to 89) | Not reported | 45 (37 to 52) |
| 6 mo to 8 y | Not reported | Not reported | 39 (20 to 54) |
| 9–17 y | Note reported | Not reported | 43 (23 to 58) |
| Influenza B/Yamagata | |||
| Overall all ages | 48 (39 to 55) | Not reported | NA |
| 6 mo to 8 y | 77 (49 to 90) | Not reported | NA |
| 9–17 y | 28 (1 to 48) | Not reported | NA |
VE is estimated as 100% × (1 − odds ratio [ratio of the odds of being vaccinated among outpatients with influenza-positive test results on the CDC’s real-time reverse transcriptase–polymerase chain reaction to the odds of being vaccinated among outpatients with influenza-negative test results]); odds ratios were estimated by using logistic regression. Adjusted for study site, age group, sex, race and/or ethnicity, self-rated general health, number of days from illness onset to enrollment, and month of illness using logistic regression. NA, not applicable.