Table 6. Survival time and half-lives of various recombinant viruses on the surface of human skin*.

Subtype†	Median survival time (95% CI), h‡	Median half-life (95% CI), h‡
		4 (log10 FFU)	3 (log10 FFU)	2 (log10 FFU)
rH5N1-H5N3-NA	2.04 (1.79–2.31)	0.09 (0.08–0.10)	0.12 (0.10–0.14)	0.18 (0.15–0.21)
rH5N1-H5N3-HA	2.06 (1.77–2.37)	0.09 (0.08–0.11)	0.12 (0.10–0.14)	0.18 (0.15–0.21)
rH5N3-H5N1-NA	4.65 (3.94–5.43)	0.20 (0.17–0.25)	0.27 (0.23–0.33)	0.41 (0.35–0.49)
rH5N3-H5N1-NS	2.18 (1.83–2.55)	0.10 (0.08–0.12)	0.13 (0.11–0.16)	0.19 (0.16–0.23)
rH5N3-H5N1-M	2.22 (1.87–2.61)	0.10 (0.08–0.12)	0.13 (0.11–0.16)	0.19 (0.16–0.24)
rH5N3-H5N1-HA	2.16 (1.83–2.52)	0.09 (0.07–0.11)	0.13 (0.11–0.15)	0.19 (0.16–0.23)

*FFU, focus-forming unit. †A/crow/Kyoto/53/04 (H5N1) recombined with the NA and HA genes of A/Duck/Hong Kong/820/80 (H5N3) are defined as rH5N1-H5N3-NA and rH5N1-H5N3-HA, respectively. In addition, A/Duck/Hong Kong/820/80 (H5N3) recombined into the NA, NS, M, and HA genes of A/crow/Kyoto/53/04 (H5N1) was defined as rH5N3-H5N1-NA, rH5N3-H5N1-NS, rH5N3-H5N1-M, rH5N3-H5N1-HA. ‡The elapsed time was used as the explanatory variable (x-axis), and the logarithmic virus titer was used as the explained variable (y-axis). A linear regression analysis with logarithmic link function was performed for each virus to create a curve of regression (Appendix Figure 4). Since the detection limit of each influenza virus titer was 10¹ FFUs, the X value (when the Y value of the regression curve was 1.0) was used as the survival time. §The half-life of each virus was calculated from the slope of each regression curve when the amount of virus remaining on the surface was 2, 3, or 4 log₁₀ FFUs.