Table 2.
Overall influenza vaccine effectiveness (all vaccines combined*) during the 2018–2019 and 2019–2020 influenza seasons.
| Group | Influenza Positive % | Influenza Negative % | Vaccine Effectiveness |
|
|---|---|---|---|---|
| Unadjusted % (95% CI) |
Adjusted** % (95% CI) |
|||
| Overall | 14 | 22 | 40 (30, 49) | 37 (27, 46) |
| Influenza A | 17 | 22 | 26 (13, 38) | 31 (17, 42) |
| Influenza B | 9 | 22 | 63 (51, 72) | 52 (36, 64) |
| Age 18–49 years | 12 | 20 | 48 (37, 57) | 46 (35, 56) |
| Age 50–64 years | 24 | 26 | 13 (−13, 34) | 13 (−14, 34) |
| Female sex | 17 | 24 | 37 (24, 47) | 33 (19, 44) |
| Male sex | 11 | 18 | 46 (29, 59) | 46 (28, 59) |
| High-risk condition† | 22 | 30 | 34 (19, 47) | 33 (18, 46) |
| No high-risk condition | 10 | 16 | 44 (29, 55) | 42 (26, 54) |
| 2018–2019 season | 19 | 29 | 40 (20, 55) | 41 (21, 56) |
| 2019–2020 season | 13 | 20 | 41 (30, 51) | 36 (23, 47) |
Bold indicates non-overlapping intervals. *Vaccinated: Recombinant and Standard dose egg-based vaccines (Afluria, Fluarix, FluLaval, SD Fluzone, and FlucelVax).
**Multivariable logistic regression model adjusted for age, race, sex, season, and high-risk conditions, except that the stratified variable is not included as an adjustment in its own analysis.
†High-risk conditions include chronic cardiovascular, respiratory disease, among others. See Appendix 1.