Selection of a SARS-CoV-2 Surrogate for Use in Surface Disinfection Efficacy Studies with Chlorine and Antimicrobial Surfaces

Initial recommendations for surface disinfection to prevent SARS-CoV-2 transmission were developed using previous evidence from potential surrogates. To the best of our knowledge, no appropriate surrogate for SARS-CoV-2 has been identified or confirmed for chlorine and antimicrobial surface disinfection. We completed a study to evaluate the efficacy of two hypothesized antimicrobial surfaces, and four chlorine solutions on nonporous and porous surfaces, against SARS-CoV-2 and three potential SARS-CoV-2 surrogates [coronavirus mouse hepatitis virus (MHV) and bacteriophages Phi6 and MS2], to identify a BSL-1 or BSL-2 virus to use in future studies. We found SARS-CoV-2 can be reduced >4 log 10 on porous and nonporous surfaces within 30 s upon exposure to 0.5% NaOCl. The results indicate coronavirus MHV-GFP is inactivated faster than SARS-CoV-2 (MHV-GFP ≥ 6.08 log 10 ; SARS-CoV-2 = 0.66 log 10 at 30 s with 0.05% NaOCl on steel) and MS2 is inactivated more slowly. Phi6 is inactivated like SARS-CoV-2, and we propose Phi6 as a slightly conservative surrogate for SARS-CoV-2 chlorine disinfection. Additionally, disinfection of bacteriophages on wood was challenging, and exposure to antimicrobial surfaces had no disinfection efficacy as tested. We recommend using 0.5% chlorine on surfaces for a minimum of 30 s of contact to disinfect SARS-CoV-2 and recommend additional research on Phi6 disinfection with varied surfaces and conditions.