Infectivity duration of HCoV-OC43, a surrogate for SARS-CoV-2, in artificial bodily fluids on stainless steel simulating common nonporous surfaces

We investigated the infectivity and persistence of SARS-CoV-2 on environmental surfaces by enlisting human beta-coronavirus OC43 as a surrogate. This study evaluated its stability on nonporous stainless steel surfaces under two absolute humidity (AH) conditions when embedded in three mucin concentrations to mimic natural contamination with bodily fluids commonly occurring in healthcare environments.Stainless steel coupons were inoculated with OC43 in artificial saliva with mucin concentrations of 0%, 0.3%, and 3% (wt/vol) and held in a controlled environmental chamber at AH 14.4 g/m³ (26°C/57% relative humidity [RH]) and 3.04 g/m³ (18°C/20% RH) for up to 22 days. Three coupons at specific time points were selected, and each coupon eluate was serially diluted and incubated on HRT-18G cells in 96-well plates for 7 days. Cytopathic effect (CPE) in infected cells was microscopically scored for remaining infectious titer using the TCID₅₀ method. Select CPE-negative wells were further assayed by RT-qPCR to confirm the presence of replicative virus and ensure viral infectivity.OC43 remained infectious up to 14, 3, and 2 days in high, low, and no mucin, respectively, at AH 14.4 g/m³ (26°C/57% RH). However, at AH 3.04 g/m³ (18°C/20% RH), OC43 remained infectious in all matrix types throughout the 22-day test.Our study demonstrates that mucin content in surface contaminants enhances OC43 stability on stainless steel surfaces at higher AH, while the protective effect of mucin is negligible at lower AH. Overall, our findings implicate that virus contamination on nonporous surfaces could present prolonged risk exposure to SARS-CoV-2 if left unmitigated.IMPORTANCEThis study will lead to a greater understanding of the impact of bodily fluids on survival and transmission risk of coronaviruses from fomites and is critical for developing effective infection control strategies.