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1.
Preprint in English | bioRxiv | ID: ppbiorxiv-512011

ABSTRACT

The virucidal activity of a quaternary ammonium compound (QAC)-based antimicrobial coating used by the UK rail industry during the COVID-19 pandemic was evaluated using the bacteriophage {phi}6 as a surrogate for SARS-CoV-2. Immediately after application and in the absence of interfering substance, the product showed efficacy (>3 log10 reduction) on some materials typically used in rail carriages (stainless steel, high pressure laminate and plastic), variable efficacy on glass and no efficacy (<3 log10 reduction) on a train armrest made of Terluran 22. If, after application of the product, the surfaces remained undisturbed, the antimicrobial coating retained its efficacy for at least 28 days on all materials where it was effective immediately after application. However, regardless of the material coated or time since application, the presence of organic debris (fetal bovine serum) significantly reduced the viricidal activity of the coating. Wiping the surface with a wetted cloth after organic debris deposition was not sufficient to restore efficacy. We conclude that the product is likely to be of limited effectiveness in a busy multi-user environment such as public transport. ImportanceThis study evaluated the performance of a commercially available antimicrobial coating used by the transport industry in the UK during the COVID-19 pandemic. While the product initially showed efficacy against {phi}6 when applied to some materials, when organic debris was subsequently deposited, the efficacy was severely diminished and could not be recovered through wiping (cleaning) the surface. This highlights the importance of including relevant materials and conditions when evaluating antimicrobial coatings in the laboratory. Further efforts are required to identify suitable infection prevention and control practices for the transport industry.

2.
Preprint in English | medRxiv | ID: ppmedrxiv-21265208

ABSTRACT

ObjectiveTo evaluate the potential for long-distance (over two metres) airborne transmission of SARS-CoV-2 in indoor community settings and investigate factors which may impact this transmission. DesignSystematic review and narrative synthesis. Data sourceMEDLINE, Embase, medRxiv, Arxiv and WHO COVID-19 Research Database for studies published from 27 July 2020 to 21 April 2021; existing relevant rapid systematic reviews for studies published between 1 January to 27 July 2020. Eligibility criteria for study selectionObservational studies that included a thorough epidemiological assessment of routes of transmission and which reported on the likelihood of airborne transmission of SARS-CoV-2 at a distance greater than two metres in indoor community settings. Data extraction and synthesisData extraction was completed by one reviewer and independently checked by a second reviewer. Primary outcomes were COVID-19 infections via airborne transmission over distances greater than two metres and any factors that may have modified transmission risk. Included studies were rated using a quality criteria checklist (QCC) for primary research and certainty of key outcomes was determined using GRADE. Narrative synthesis was themed by setting. ResultsOf the 3,780 articles screened for inclusion, 15 publications reporting on 13 epidemiological investigations were included (three high, six medium and four low quality). Airborne transmission at distances greater than two metres was likely to have occurred for some or all transmission events in 12 studies and was unclear in one study (GRADE: very low certainty). In all studies, one or more factors plausibly increased the likelihood of long-distance airborne transmission occurring, particularly insufficient air replacement (GRADE: very low certainty), recirculating air flow (GRADE: very low certainty) and singing (GRADE: very low certainty). In nine studies, the primary cases were reported as being asymptomatic, presymptomatic or around symptom onset at the time of transmission. ConclusionThis rapid systematic review found evidence of long-distance airborne transmission of SARS-CoV-2 in indoor community settings and identified factors that likely contributed to this transmission in all included studies. These results strengthen the need for adequate mitigation measures in indoor community settings, particularly adequate ventilation with fresh air, and caution required with the use of recirculating air flow systems. Systematic review registrationPROSPERO CRD42021236762

3.
Preprint in English | medRxiv | ID: ppmedrxiv-20191411

ABSTRACT

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.

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