Persistence of two coronaviruses and efficacy of steam vapor disinfection on two types of carpet.

Background: Coronaviruses, a group of highly transmissible and potentially pathogenic viruses, can be transmitted indirectly to humans via fomites. To date, no study has investigated their persistence on carpet fibers. Establishing persistence is essential before testing the efficacy of a disinfectant.

Methods: The persistence of BCoV and HCoV OC43 on polyethylene terephthalate (PET) and nylon carpet was first determined using infectivity and RT-qPCR assays. Then, the disinfectant efficacy of steam vapor was evaluated against both coronaviruses on nylon carpet.

Results: Immediately after inoculation of carpet coupons, 32.50% of BCoV and 3.87% of HCoV OC43 were recovered from PET carpet, compared to 34.86% of BCoV and 24.37% of HCoV OC43 recovered from nylon carpet. After incubation at room temperature for 1 h, BCoV and HCoV OC43 showed a 3.6 and > 2.8 log₁₀ TCID₅₀ reduction on PET carpet, and a 0.6 and 1.8 log₁₀ TCID₅₀ reduction on nylon carpet. Based on first-order decay kinetics, the whole gRNA of BCoV and HCoV OC43 were stable with k values of 1.19 and 0.67 h^- 1 on PET carpet and 0.86 and 0.27 h^- 1 on nylon carpet, respectively. A 15-s steam vapor treatment achieved a > 3.0 log₁₀ TCID₅₀ reduction of BCoV and > 3.2 log₁₀ TCID₅₀ reduction of HCoV OC43 on nylon carpet.

Conclusion: BCoV was more resistant to desiccation on both carpet types than HCoV OC43. Both viruses lost infectivity quicker on PET carpet than on nylon carpet. Steam vapor inactivated both coronaviruses on nylon carpet within 15 s.