Published Efficacy Field Studies of CAIV in Healthy Children

Monovalent Vaccine Studies
StudyVaccine Strain(s)Number Immunized*Number of CAIV Doses and (Titer Log10)Study SeasonComparison Group (n)Outbreak StrainEnd PointsEfficacy % (95% CI)
Feldman et al109A(H1N1)281 (6.2)1982–1983A(H3N2)A(H1N1)ILI plus PC or SCR34 (−75–76)
CAIV (16)
A(H3N2) inactivated (12)
Placebo (23)
Belshe et al110A(H3N2)521 (6.5)1982–1983A(H1N1)A(H3N2)§Febrile illness62 (7–85)
CAIV (51)A(H1N1)
Wright et al96A(H3N2)101 (6.4)1980–1981Age-matched (26)A(H3N2)Febrile illness100 (−4–100)
Monovalent and Bivalent Vaccine Study
Gruber et al95A(H3N2) or A(H3N2) and A(H1N1)931 (6.2)1991–1992A(H1N1) or placebo (88)A(H3N2)ILI plus PC67 (18–85)
Bivalent Vaccine Studies
Clover et al67A(H1N1) and A(H3N2)562 single annual doses (7.0)1986–1987TIV (54), placebo (82)A(H1N1)ILI plus PC81 (1–97)
Piedra et al106A(H1N1) and (H3N2)611, 2, or 3 single annual doses (7.0)1987–1988TIV (62), placebo (69)A(H3N2)ILI plus PC89 (35–98)
NA54None given1988–1989TIV (55), placebo (60)A(H1N1)100 (18–100)
Neuzil et al46A(H1N1) and A(H3N2)250Annual (5.7–7.3)#1986–1987 and 1988–1989TIV (277)H1N1ILI plus PC96**
2571987–1988 and 1989–1990Inactivated B (259)A(H3N2)68** (1–90)
Trivalent Studies
Belshe et al85,86A(H1N1), A(H3N2), and B10702 dose year 1†† (6.7)1996–1997Placebo (532)A(H3N2)ILI and PC95 (88–97)
B91 (79–96)
9171 dose year 2 (7.0)1997–1998Placebo (441)A(H3N2)87 (78–93)
B100 (79–100)
  • ILI indicates influenza-like illness; PC, positive culture for influenza; SCR, fourfold antibody increase; NA, not applicable.

  • * Recipients of CAIV vaccine matching the type or subtype of circulating influenza strains listed under outbreak.

  • Estimated efficacy compared with placebo recipients.

  • Compared with recipients of placebo.

  • § Outbreak was predominantly influenza A(H3N2), but 21% of isolates were A(H1N1).

  • In 3- to 9-year-old children, estimated efficacies were 81% after 2 annual doses and 46% after 1 annual dose.

  • Person-years are shown.

  • # Children younger than 3 years received a 10-fold lower dose. Therefore, children younger than 3 years received doses of 4.7 to 6.3, and those 3 years and older received doses of 5.7 to 7.3.

  • ** In recipients of annual doses.

  • †† 18% of children received only 1 dose year 1.