
Not true, disinfectants like Parvocide can be used to kill parvovirus, it was developed specifically to kill parvovirus. The six months period dates back to 1978 when there was no virus specific disinfectant. Parvocide was rapidly developed & has been updated on a regular basis to take into account the various mutations of the virus.
My late friend's who ran a boarding kennels for more than 50 years, was one of the first to use it, they only had one case of Parvo in the kennels & that developed a week into the dog's 14 day stay, the dog was immediately isolated & barrier nursed. The Parvo never spread through the kennels as it did in the local RSPCA kennels which lost 3/4s of the dog's.