Table 5. Field effectiveness of pandemic vaccines, by case definition, age group and study period.

	Age group	FVE (%)	95% CI
ILI, epidemic period
Vaccinated for ≤3 weeks or at an unknown date are considered unvaccinated	6 m–4 y	12	(−47–53)
	5–14	53	(1–82)
	15–64	77	(51–92)
	≥65	100	–
	All ages	52	(30–69)
Vaccinated for ≤3 weeks are considered unvaccinated. Vaccinated at an unknown date are considered vaccinated.	6 m–4 y	5	(−57–47)
	5–14	18	(−47–60)
	15–64	68	(38–86)
	≥65	100	–
	All ages	38	(13–58)
All vaccinees are considered vaccinated, regardless of the injection date	6 m–4 y	53	(36–66)
	5–14	59	(46–70)
	15–64	49	(33–62)
	≥65	30	(−124–88)
	All ages	54	(45–61)
ILI, post-epidemic period
Vaccinated for ≤3 weeks or at an unknown date are considered unvaccinated	6 m–4 y	65	(14–90)
	5–14	28	(−45–70)
	15–64	11	(−38–47)
	≥65	100	–
	All ages	33	(4–55)
Vaccinated for ≤3 weeks are considered unvaccinated. Vaccinated at an unknown date are considered vaccinated.	6 m–4 y	56	(−2–85)
	5–14	28	(−45–70)
	15–64	11	(−38–47)
	≥65	100	–
	All ages	31	(1–53)
All vaccinees are considered vaccinated, regardless of the injection date	6 m–4 y	56	(−2–85)
	5–14	5	(−78–56)
	15–64	6	(−44–43)
	≥65	100	–
	All ages	24	(−7–47)
Laboratory-confirmed influenza
Vaccinated for ≤3 weeks or at an unknown date are considered unvaccinated	6 m–4 y	100	–
	5–14	72	(−28–98)
	15–64	74	(−15–99)
	All ages	86	(56–98)
Vaccinated for ≤3 weeks are considered unvaccinated. Vaccinated at an unknown date are considered vaccinated.	6 m–4 y	69	(1–95)
	5–14	72	(−28–98)
	15–64	48	(−64–91)
	All ages	64	(21–87)
All vaccinees are considered vaccinated, regardless of the injection date	6 m–4 y	44	(4–70)
	5–14	44	(−4–73)
	15–64	69	(19–92)
	All ages	49	(25–67)