Purpose: This study investigated the virucidal efficacy of two commercial disinfectants containing a combination of hydrogen peroxide (5-10%), acids and surfactants, at the recommended use dilution (1:16) against human norovirus GII.4 Sydney and the cultivable surrogate, Tulane virus (TuV).
Methods: The products were tested against the viruses using suspension and carrier (stainless steel coupons) assays according to the American Society for Testing and Materials protocols E1052-11 and E1053-11, respectively, with and without an additional organic load. Log10 inactivation was determined based on reduction in genomic copies (GC; RT-qPCR preceded by RNase treatment) for human norovirus, and mammalian cell culture infectivity assay for TuV. The impact of rubbing or removal of virus in conjunction with application of the disinfectants was not evaluated in this study.
Results: In suspension assays testing both products, human norovirus GII.4 Sydney titer was decreased by 4.3 ± 0.3 log10 after 20 min, with negligible impact from organic load (p>0.05). The disinfectant efficacy decreased (p<0.05) when tested by surface assay, with an average reduction of 2.6 ± 0.1 log10 GC after 20 min in the absence of organic load; after addition of organic load, <1.0 log10 inactivation was achieved. Both products fully inactivated infectious TuV (5.5 log10 reduction) after 5 min on stainless steel surfaces when no organic load was added; however, after addition of organic load, 30 min was required to achieve a >4 log10 reduction.
Significance: Given adequate contact time, both disinfectants were capable of inactivating norovirus, but did not achieve the U.S. EPA standard of ≥4-log10 reduction for products claiming virucidal activity. To achieve maximum efficacy for human norovirus decontamination, these disinfectants would best be applied after surface pre-cleaning.