Table 4.
Relationship Between Days Since Vaccination With Inactivated Influenza Vaccine and Risk of a Positive Viral Test by Age, 2010–2011 to 2016–2017: Kaiser Permanente Northern California
| Days Since Vaccination (in Periods 28 Days in Length) | Age in Years, Odds Ratio (95% Confidence Interval) | |||
|---|---|---|---|---|
| Virus Type | 2 to <18 | 18 to <65 | 65 and Older | |
| Any influenza | … | Cases = 1915 | Cases = 2099 | Cases = 3994 |
| 14–41 | Reference | Reference | Reference | |
| 42–69 | 1.19 (0.78,1.83) | 1.52 (1.06,2.18) | 1.13 (0.86,1.48) | |
| 70–97 | 1.42 (0.95,2.10) | 1.73 (1.23,2.42) | 1.37 (1.06,1.76) | |
| 98–125 | 1.77 (1.20,2.60) | 1.85 (1.31,2.60) | 1.56 (1.21,2.02) | |
| 126–153 | 2.10 (1.38,3.20) | 2.18 (1.49,3.18) | 1.70 (1.29,2.25) | |
| 154+ | 1.86 (1.11,3.10) | 2.62 (1.68,4.10) | 1.92 (1.37,2.68) | |
| Respiratory syncytial virus | … | Cases = 1456 | Cases = 651 | Cases = 2042 |
| 14–41 | Reference | Reference | Reference | |
| 42–69 | 0.85 (0.58,1.24) | 1.26 (0.68,2.33) | 1.08 (0.78,1.50) | |
| 70–97 | 0.92 (0.64,1.31) | 1.48 (0.81,2.69) | 0.99 (0.72,1.35) | |
| 98–125 | 0.97 (0.66,1.42) | 1.59 (0.88,2.89) | 1.04 (0.76,1.42) | |
| 126–153 | 0.63 (0.40,0.99) | 2.10 (1.13,3.91) | 1.03 (0.74,1.43) | |
| 154+ | 0.84 (0.37,1.87) | 1.62 (0.78,3.36) | 1.35 (0.91,2.00) | |
Case positive, control test-negative analyses included only those persons who received inactivated influenza vaccination and who subsequently received a reverse-transcriptase polymerase chain reaction (PCR) test for influenza and respiratory syncytial virus (RSV) during the season in which they were vaccinated. The statistical model was a conditional logistic regression where the dependent variable was a dichotomous indicator of whether the test was positive for influenza (or RSV). The comparison group was persons who tested negative for each of the other viruses. The logistic regression was conditioned on the calendar date of the PCR test and geographic area within Northern California, and models were adjusted for age, gender, Diagnostic Cost Group, and whether patients received influenza vaccination in the prior year. Separate models were run for each outcome and age group. Results of these models need not be a weighted average of the results in Table 2 due to changes in the number of tests that are in informative strata.