Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

Volume 15, Number 3—March 2009


Meeting the Challenge of Influenza Pandemic Preparedness in Developing Countries

David S. FedsonComments to Author 
Author affiliation: University of Virginia, Charlottesville, Virginia, USA (retired)

Main Article

Table 4

Sample size requirements for a randomized controlled trial of treatment to reduce deaths in a pandemic caused by a subtype H5N1-like influenza*

Case-fatality rate, %
Reduction in no. deaths, % Total sample size (power)
Untreated Treated 80% 90% 95%
50 37.5 25 530 690 850
50 25 50 140 170 210
50 12.5 75 60 80 90

*1:1 randomization of persons to the 2 treatment groups, α = 0.05 (2-sided), χ2 test (continuity corrected). The example shown assumes a case-fatality rate of 50%, which is similar to what has been seen for patients infected with influenza virus A (H5N1). If a new pandemic virus is associated with a lower case-fatality rate, sample sizes required to show similar reductions in case-fatality rates would have to be larger.

Main Article