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Volume 19, Number 3—March 2013

Research

Effects of Vaccine Program against Pandemic Influenza A(H1N1) Virus, United States, 2009–2010

Rebekah H. Borse1, Sundar S. Shrestha, Anthony E. Fiore, Charisma Y. Atkins, James A. Singleton, Carolyn Furlow, and Martin I. MeltzerComments to Author 
Author affiliations: Author affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Main Article

Table 6

Sensitivity analysis showing number of clinical cases prevented by vaccination against influenza A(H1N1)pdm09 virus for different scenarios of vaccine distribution*

Subgroup Base case estimate
 (range)† Scenario
1: even distribution over time (range)‡ 2: distribution based on population proportion (range)§ 3: 2008 distribution (range)¶ 4: ACIP priority subgroups (range)#
6 mo–9 y 81,518
 (52,081–100,349) 131,170 
(90,932–164,352) 57,511
 (39,869–72,060) 65,093
 (45,125–81,559) 186,041
 (128,970–233,103)
10–24 y (10–17 all, 18–24 NP) 300,724
 (212,953–420,991) 279,715
 (196,606–392,577) 310,656
 (218,355–436,003) 249,981
 (175,708–350,847) 396,725
 (278,851–556,801)
Pregnant, 18–64 y 71,601
 (53,084–97,884) 44,486
 (31,726–60,936) 30,506
 (21,756–41,787) 14,809
 (10,561–20,285) 63,096
 (44,998–86,427)
HR, 25–64 y 164,958
 (116,575–228,593) 168,521
 (119,243–233,197) 183,417
 (129,784–253,810) 73,157
 (51,765–101,234) 239,017
 (169,125–330,749)
HCW, 25–64 y 123,427
 (87,287–177,144) 100,229
 (69,407–144,610) 82,764
 (57,313–119,413) 41,099
 (28,460–59,297) 142,157 
(98,441–205,104)
Contact with <6 mo 29,063
 (19,904–43,129) 28,861
 (19,686–42,794) 37,583
 (25,634–55,726) 151,525 
(103,351–224,675) 40,935
 (27,920–60,696)
25–64 y (all others) 163,327
 (107,305–248,548) 197,372 
(133,316–297,625) 366,354
 (247,455–552,439) 278,226
 (187,928–419,547) 0
>65 y
94,538 
(63,719–142,293)
99,116
 (67,121–148,741)
103,402
 (70,023–155,172)
197,547 
(133,778–296,454)
0
Total
1,029,157
 (712,908–1,458,930)
1,049,470
 (728,037–1,484,834)
1,172,194
 (810,188–1,686,411)
1,071,437
 (736,676–1,553,899)
1,067,971 (748,306–1,472,881)

Assumed % distribution by week**
6 mo–9 y, 1st dose†† 20 20 9 10 28
6 mo–9 y, 2nd dose 10 10 4 5 14
10–24 y (10–17 all, 18–24 NP) 18 18 20 16 25
Pregnant, 18–64 y 3 3 2 1 4
HR, 25–64 y 10 10 11 5 15
HCW, 25–64 y 7 7 6 3 10
Contact with <6 mo 2 2 3 12 3
25–64 y (all others) 17 17 32 24 0
>65 y 12 12 13 24 0

*Data reflect calculations made in scenarios 1 –4. ACIP, Advisory Committee on Immunization Practices; NP, not pregnant; HR, high risk; HCW, health care worker; contact, household contacts and caregivers of children <6 mo of age.
†Total number of doses administered to each population subgroup (Table 2).
‡For each population subgroup, this scenario assumes that the group received the same proportion of the total number of doses; the proportions were applied to the total number of doses administered each week (Table 2, Appendix).
§ It was assumed that the distribution of vaccines was proportional to the population.
¶Distribution of vaccine was based on estimates of estimated 2008 seasonal vaccine uptake (17,38).
#Distribution of vaccine was based exclusively on ACIP priority groupings. The proportion of doses administered was based on the proportion of doses administered to persons in each of the subgroups during the A(H1N1)pdm09 virus vaccination program, while excluding the non ACIP subgroups.
**In scenarios 1–4, the epidemiologic curve was based on the estimated A(H1N1)pdm09 vaccination curve, for which no vaccination program was assumed (Figure 1). We also assumed that the total number of vaccines administered each week remained exactly the same as outlined in Table 2, Appendix.
††For scenarios 1–4, we assumed that the 6 mo– 9 y age group required 2 doses and that a 4 wk delay was required between the first and second dose. We also assumed that no children 6 mo–9 years of age could have received their second dose until the fifth week of the vaccination program. Therefore, any doses during the first 4 wk that would have been proportioned as a second dose were added as a first dose.

Main Article

1Current affiliation: Merck & Co., Inc., Lansdale, Pennsylvania, USA.

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