Volume 15, Number 12—December 2009
Estimates of the Prevalence of Pandemic (H1N1) 2009, United States, April–July 2009
|Parameter||Observed value||Source||Ranges included in the model, %
|A||Proportion of persons with influenza who seek medical care, %||42||2007 BRFSS, 9 states†||42–58||100|
|52–55||2009 ILI survey, 10 states†|
|49–58||Delaware university survey|
|52||Chicago community survey|
|B||Proportion of persons seeking care with a specimen collected, %||25||2007 BRFSS, 9 states†||19–34||40–75|
|22–28||2009 ILI survey, 10 states†|
|19–34||Delaware university survey|
|C||Proportion of specimens collected that are sent for confirmatory testing, %||26 (through May 3)||Delaware university survey||20–30 (through May 12); 5–15 (after May 12)||50–90|
|D||Test detects influenza||Published studies||90–100||90–100|
||Proportion of confirmed cases reported to CDC
|No. reported cases||43,677||Reports to CDC through July 23, 2009||4,759 (through May 12); 33,909 (after May 12)||5,009|
*BFRSS, Behavioral Risk Factor Surveillance Survey; ILI, Influenza-like illness; CDC, Centers for Disease Control and Prevention. States include California, Colorado, Connecticut, Georgia, Maryland, Minnesota, New Mexico, New York, Oregon, and Tennessee.
†Parameter estimates and sources are described in further detail in the Technical Appendix.