Public Health England has confirmed that its current recommendations for quarantining books remain in place based on a 72 hour quarantining regime. These can be found here: https://www.librariesconnected.org.uk/page/public-health-england-stateme...
This follows a study produced by OCLC which looked at stacked books and other library materials and suggested that the virus was detectable after 6 days (https://www.webjunction.org/news/webjunction/test4-results.html.)
Jenifer Smith, PHE's Deputy Medical Director, said that she had looked at the study and that it is “broadly compatible with the evidence base on which the quarantine guidance is based. In other words, there is a marked decline in the amount of virus remaining after 48 hours, falling still further after 72 hours.”
“It is important to recognise that what will determine whether or not disease is transmitted is not so much whether or not virus can be detected, but whether there is virus remaining in a state such that disease is transmitted. As it is not clear what the viable virus dose for infection is, or how closely the inoculation dose used compares to the amount of virus typically found deposited on library books, and in the absence of strong epidemiological evidence to the contrary, this study would not form a basis on which to change current guidance.”