The transmission of SARS-CoV-2 is likely to occur through a number of routes, including contact with contaminated surfaces. Many studies have used RT-PCR analysis to detect SARS-CoV-2 RNA on surfaces but seldom has viable virus been detected. This paper investigates the viability over time of SARS-CoV-2 dried onto a range of materials and compares viability of the virus to RNA copies recovered, and whether virus viability is concentration dependant. Viable virus persisted for the longest time on surgical mask material and stainless steel with a 99.9% reduction in viability by 122 and 114 hours respectively. Viability of SARS-CoV-2 reduced the fastest on a polyester shirt, with a 99.9% reduction within 2.5 hours. Viability on the bank note was reduced second fastest, with 99.9% reduction in 75 hours. RNA on all the surfaces exhibited a one log reduction in genome copy recovery over 21 days. The findings show that SARS-CoV-2 is most stable on non-porous hydrophobic surfaces. RNA is highly stable when dried on surfaces with only one log reduction in recovery over three weeks. In comparison, SARS-CoV-2 viability reduced more rapidly, but this loss in viability was found to be independent of starting concentration. Expected levels of SARS-CoV-2 viable environmental surface contamination would lead to undetectable levels within two days. Therefore, when RNA is detected on surfaces it does not directly indicate presence of viable virus even at high CT values. Importance This study shows the impact of material type on the viability of SARS-CoV-2 on surfaces. It demonstrates that the decay rate of viable SARS-CoV-2 is independent of starting concentration. However, RNA shows high stability on surfaces over extended periods. This has implications for interpretation of surface sampling results using RT-PCR to determine the possibility of viable virus from a surface, where RT-PCR is not an appropriate technique to determine viable virus. Unless sampled immediately after contamination it is difficult to align RNA copy numbers to quantity of viable virus on a surface.

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Understanding how Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is spread within the hospital setting is essential if staff are to be adequately protected, effective infection control measures are to be implemented and nosocomial transmission is to be prevented. The presence of SARS-CoV-2 in the air and on environmental surfaces around hospitalised patients, with and without respiratory symptoms, was investigated. Environmental sampling was carried out within eight hospitals in England during the first wave of the COVID-19 outbreak. Samples were analysed using reverse transcription polymerase chain reaction (RT-PCR) and virus isolation assays. SARS-CoV-2 RNA was detected on 30 (8.9%) of 336 environmental surfaces. Ct values ranged from 28.8 to 39.1 equating to 2.2 x 105 to 59 genomic copies/swab. Concomitant bacterial counts were low, suggesting the cleaning performed by nursing and domestic staff across all eight hospitals was effective. SARS-CoV-2 RNA was detected in four of 55 air samples taken < 1 m from four different patients. In all cases, the concentration of viral RNA was low and ranged from < 10 to 460 genomic copies per m3 of air. Infectious virus was not recovered from any of the PCR positive samples analysed. Effective cleaning can reduce the risk of fomite (contact) transmission but some surface types may facilitate the survival, persistence and/or dispersal of SARS-CoV-2. The presence of low or undetectable concentrations of viral RNA in the air supports current guidance on the use of specific PPE ensembles for aerosol and non-aerosol generating procedures.

The survival of newer variants of SARS-CoV-2 on a representative surface has been compared to the established UK circulating isolate to determine whether enhanced environmental stability could play a part in their increased transmissibility. Stainless steel coupons were inoculated with liquid cultures of the three variants, with coupons recovered over seven days and processed for recoverable viable virus using plaque assay. After drying, there was no significant difference in inactivation rates between variants, indicating that there is no increased environmental persistence from the new variants.

BackgroundAn unprecedented outbreak of monkeypox virus (MPXV) infections in non-endemic countries has been recognised since 12 May 2022. More than 6000 cases have been identified globally with more than 1500 in the UK by July 2022. Transmission of MPXV is believed to be predominantly through direct contact with lesions or infected body fluids, with possible involvement of fomites and large respiratory droplets. Importantly, a case of monkeypox in a UK healthcare worker in 2018 was suspected to be due to virus exposure while changing bedding.MethodsWe investigated environmental contamination with MPXV from infected patients admitted to isolation rooms in the UK, to inform infection prevention and control measures. Surface swabs of high-touch areas in isolation rooms, of healthcare worker personal protective equipment (PPE) in doffing areas, and from air samples collected before and during bedding change were analysed using MPXV qPCR to assess contamination levels. Virus isolation was performed to confirm presence of infectious virus in key positive samples.FindingsWe identified widespread surface contamination (66 positive out of 73 samples) in occupied patient rooms (MPXV DNA Ct values 24·7-38·6), on healthcare worker personal protective equipment after use, and in doffing areas (Ct 26·3-34·3). Five out of fifteen air samples taken were positive. Significantly, three of four air samples collected during a bed linen change in one patient’s room were positive (Ct 32·7-35·8). Replication-competent virus was identified in two of four samples selected for viral isolation, including from air samples collected during the bed linen change.InterpretationThese data demonstrate significant contamination in isolation facilities and potential for aerosolisation of MPXV during specific activities. PPE contamination was observed after clinical contact and changing of bed linen. Additionally, contamination of hard surfaces in doffing areas supports the importance of cleaning protocols, PPE use and doffing procedures.FundingNo funding source for this study

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Human transmission is believed to occur primarily through direct transfer of infectious droplets or aerosols. However, fomite transmission through contact with contaminated surfaces may also play an important role.