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. 2012 Jul 25;55(7):951–959. doi: 10.1093/cid/cis574

Table 3.

Percent Vaccinated by Case/Control Status and Crude and Adjusted Vaccine Effectivenessa by Age Group and Vaccine

Age Group Influenza Positive (Cases)
 Influenza Negative (Controls)
 Unadjusted
 Adjusted
No. Vaccinated/Total % Vaccinated No. Vaccinated/Total % Vaccinated VE % 95% CI VE %b 95% CI
Any seasonal vaccine
 All ages 317/1028 31 1958/3684 53 61 55–66 60 54–66
 6 months–2 years 47/93 51 465/675 69 54 29–70 58 31–74
 3–8 years 79/269 29 438/756 58 70 59–78 69 56–77
 9–49 years 104/479 22 534/1425 37 54 41–64 51 36–62
 50–64 years 47/124 38 263/470 56 52 29–68 51 25–68
 ≥65 years 40/63 63 258/358 72 33 −18 to 62 36 −22 to 66
Inactivated seasonal vaccine
 All ages 269/980c 27 1730/3456d 50 62 56–68 62 55–68
 2–8 years 66/283 23 443/833 53 73 64–80 71 58–78
 9–49 years 91/466 20 477/1368 35 55 42–65 52 37–64
 ≥50 years 79/179 44 491/798 62 51 32–64 47 24–63
Live attenuated seasonal vaccine
 2–49 years 31/623e 5 162/1443f 11 59 39–72 65 46–77
 2–8 years 22/239 9 128/518 25 69 50–81 71 50–83
 9–49 years 9/384 2 34/925 4 37 −33 to 70 42 −28 to 74

Abbreviations: CI, confidence interval; VE, vaccine effectiveness.

a Vaccinated subjects are defined by last dose of the vaccine received ≥14 days before symptom onset.

b For all ages models: adjusted for study site, age in years, age group, race, insurance, enrollment site, and high-risk condition. For age-specific models: adjusted for study site, age in years, race, insurance, enrollment site, and high-risk condition.

c Excluded subjects with live attenuated vaccine (n = 31) and unknown vaccine type (n = 17) prior to illness onset date.

d Excluded subjects with live attenuated vaccine (n = 162) and unknown vaccine type (n = 66) prior to illness onset date.

e Excluded subjects aged <2 years or >49 years (n = 240) and those with inactivated vaccine (n = 157) and unknown vaccine type (n = 8) prior to illness onset date.

f Excluded subjects aged <2 years or >49 years (n = 1295) and those with inactivated vaccine (n = 920) and unknown vaccine type (n = 26) prior to illness onset date.