The sensitivity of this duplex real - time RT - PCR assay was 0 . 02 TCID 50 ( 50 % tissue culture infective dose ) for H5N1 and 0 . 2 TCID 50 for the pandemic H1N1 , which was the same as that of each single - target RT - PCR for pandemic H1N1 and even more sensitive for H5N