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Volume 15, Number 12—December 2009

Dispatch

Estimates of the Prevalence of Pandemic (H1N1) 2009, United States, April–July 2009

Carrie ReedComments to Author , Frederick J. Angulo, David L. Swerdlow, Marc Lipsitch, Martin I. Meltzer, Daniel Jernigan, and Lyn Finelli
Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (C. Reed, F.J. Angulo, D.L. Swerdlow, M.I. Meltzer, D. Jernigan, L. Finelli); Harvard School of Public Health, Boston, Massachusetts, USA (M. Lipsitch)

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Table 2

Estimates of pandemic (H1N1) 2009–related cases and rates of illness and hospitalization by age distribution of confirmed case-patients, United States, April–July 2009

Parameter Estimated no. case-patients
Estimated rate/100,000*
Median 90% range Median 90% range
Total no. case-patients by age group, y† 3,052,768 1,831,115–5,720,928 997 598–1,868
0–4 397,033 238,149–744,045 1,870 1,122–3,505
5–24 1,820,284 1,091,845–3,411,237 2,196 1,317–4,115
25–49 612,862 367,608–1,148,511 577 346–1,081
50–64 180,297 108,146–337,879 319 192–599
>65
42,292
25,368–79,256

107
64–201
No. hospitalized case-patients by age group, y 13,764 9,278–21,305 4.5 3.0–7.0
0–4 2,768 1,866–4,285 13.0 8.8–20.2
5–24 4,991 3,364–7,725 6.0 4.1–9.3
25–49 3,440 2,319–5,324 3.2 2.2–5.0
50–64 1,912 1,289–2,959 3.4 2.3–5.2
>65
654
441–1,012

1.7
1.1–2.6
Multiplier
Hospitalized 2.7 1.7–4.5
Nonhospitalized 79 47–148
Through May 12 33 23–49
After May 12 84 50–163

*United States Population Estimates, 2009.
†Age distributions from line list and aggregate reports of laboratory-confirmed cases and hospitalizations to the Centers for Disease Control and Prevention through July 23, 2009.

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