Cost-effectiveness analysis of universal influenza vaccination with quadrivalent inactivated vaccine in the United States

Figures & data

Table 1. Base-case health outcomes

Outcome	IIV3/LAIV3	IIV4	IIV4–IIV3/LAIV3
Number of influenza cases	19 984 438	19 954 187	–30 251
Number of hospitalizations*	212 030	208 518	–3512
Number of deaths*	30 645	29 923	–722
LYs lost	225 372	220 560	–4812
QALYs lost	171 428	167 832	–3596

* Influenza-associated hospitalizations and deaths were defined based on underlying respiratory and circulatory ICD-9 codes; IIV3, trivalent inactivated vaccine; IIV4, quadrivalent inactivated vaccine; LAIV3, trivalent live attenuated influenza vaccine; LY, life year; QALY, quality adjusted life year.

Table 2. Base-case cost outcomes

Outcome	IIV3/LAIV3	IIV4	IIV4–IIV3/LAIV3
Vaccination, $	4 820 186 421	5 272 349 339	452 162 918
MD visit for influenza, $	670 432 972	668 570 170	–1 862 802
Outpatient care, $	1 129 120 734	1 126 022 185	–3 098 549
Inpatient care, $*	6 349 791 900	6 243 737 329	–106 054 571
Antiviral, $	272 056 318	271 487 534	–568 784
Total medical costs, $	13 241 588 345	13 582 166 558	340 578 213
Caregiver work absenteeism, $	820 806 924	838 294 517	17 487 593
Work absenteeism, $	1 853 210 765	1 819 848 042	–33 362 723
Lifetime lost productivity, $	9 854 058 873	9 651 268 534	–202 790 340
Total non-medical costs, $	12 528 076 562	12 309 411 093	–218 665 470
Total costs, $	25 769 664 907	25 891 577 650	121 912 743

* Influenza-associated hospitalizations and deaths were defined based on underlying respiratory and circulatory ICD-9 codes; IIV3, trivalent inactivated vaccine; IIV4, quadrivalent inactivated vaccine; LAIV3, trivalent live attenuated influenza vaccine; MD, medical doctor.

Table 3. Alternative scenario cost-effectiveness analyses

Analysis	Strategy	Total		Incremental		ICER, $/QALY gained
		Cost, $millions	QALYs lost, thousands	Additional cost, $millions	QALYs gained, thousands
High match (76.5%; 2006/2007 season)^5	IIV3/LAIV3	15 817	170	-	-	Ref
	IIV4	16 240	168	423	1.7	256 690
Low match (18.7%; 2005/2006 season)^5	IIV3/LAIV3	16 031	174	-	-	Ref
	IIV4	16 245	168	214	5.8	37 045
High circulation (34.3%) low match (16.6%; 2008/2009 season)^5	IIV4	16 113	165	-	-	Ref
	IIV3/LAIV3	16 122	176	9	–10	Dominated
Low circulation of influenza B among those >65 y of age (4%, 2010–11)^10	IIV3/LAIV3	15 916	171	-	-	Ref
	IIV4	16 329	170	412	1.2	340 772
High circulation of influenza B among > 65 y (51%, 2007–2008)^10	IIV3/LAIV3	15,916	171	-	-	Ref
	IIV4	15.991	163	75	8.8	8623

ICER, incremental cost-effectiveness ratio; IIV3, trivalent inactivated vaccine; IIV4, quadrivalent inactivated vaccine; LAIV3, trivalent live attenuated influenza vaccine; QALY, quality adjusted life year; Ref, reference.

Figure 1. DSA tornado diagram comparing IIV4 vs. IIV3/LAIV3.

Figure 2. Scatter plot of incremental costs vs. incremental QALYs.

Figure 3. Model.

Table 4. Vaccine coverage and probability of influenza estimates

Age group, y	Vaccine coverage, %	IIV3/LAIV3 coverage among those vaccinated, %	Probability of influenza, unvaccinated, %^2
<5	47.24^29^-^31	73.27/26.73*	20.3
5–17	21.28^29^-^31	63.28/36.72*	10.2
18–49	30.5^30	93.28/6.72^34	6.6
50–64	44.5^30	100/0^†	6.6
≥65	66.6^30	100/0^†	9.0

* Calculated based on: National Immunization Survey data estimating that 17% of children received at least one trivalent seasonal LAIV3 in the past 12 mo (CDC, personal communication); and CDC data that 63.6% (0–4 y) and 46.3% (5–17 y) received IIV3 or LAIV3;^{30 †}Assumption, as LAIV3 is not indicated for adults ≥ 50 y; IIV3, trivalent inactivated vaccine; LAIV3, trivalent live attenuated influenza vaccine.

Table 5. Vaccine efficacy estimates

Age group, y	IIV3 influenza A, % (95% CI)	IIV3 influenza B vaccine-matched, % (95% CI)	IIV3 influenza B vaccine-mismatched, % (95% CI)	Overall, %
				IIV3*	IIV4*	LAIV3
<5	59 (41; 71)^7	66 (12; 94)^†	44 (8; 82)^†	58	60	83^8
5–17	61 (48; 70)^7	77 (18; 94)^†	52 (19; 72)^‡	62	64	82^7
18–49	61 (48; 70)^8	77 (18; 94)^18	52 (19; 72)^18	62	64	62^36
50–64	61 (48; 70)^8	73 (19; 99)^†	49 (12; 90)^†	61	63	NA
≥65	58 (34; 73)^35	69 (15; 99)^†	47 (9; 85)^†	58	60	NA

* Calculated based on efficacies against influenza A^7,8,35 and matched and mismatched influenza B;¹⁸ and 11-y means of the proportion of circulating virus that was influenza A (79%) and matched influenza B (50%);^{5 †}Based on extrapolation of adult efficacy estimates with the assumption that inactivated vaccine efficacy is reduced in young children and elderly, due to lack of data in the literature for these age groups; ^‡Assumed to be the same as adult efficacy estimates; ¹⁸CI, confidence interval; IIV3, trivalent inactivated vaccine; IIV4, quadrivalent inactivated vaccine; LAIV3, trivalent live attenuated influenza vaccine.

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