A post-occupancy study of ventilation effectiveness from high-resolution CO2 monitoring at live theatre events to mitigate airborne transmission of SARS-CoV-2.

Mass-gathering events were closed around the world in 2020 to minimise the spread of the SARS-CoV-2 virus. Emerging research on the transmission of SARS-CoV-2 emphasised the importance of sufficient ventilation. This paper presents the results of an indoor air quality (IAQ) monitoring study over 82 events in seven mechanically ventilated auditoria to support the UK government Events Research Programme. Indoor carbon dioxide concentration was measured at high resolution before, during, and after occupancy to allow for assessment of the ventilation systems. Generally, good indoor air quality was measured in all auditoria, with average IAQ found to be excellent or very good for 70% of spaces. In some auditoria, spatial variation in IAQ was identified, indicating poor mixing of the air. In addition, surface and air samples were taken and analysed for the presence of bacteria by culture and SARS-CoV-2 using RT-qPCR in one venue. SARS-CoV-2 RNA was detected on a small number of surfaces at very low copy numbers, which are unlikely to pose an infection risk. Under the ventilation strategies and occupancy levels investigated, it is likely that most theatres pose a low risk of long-range transmission of COVID-19.

An investigation into the presence of pathogens on inanimate surfaces in the hospital environment

BackgroundThe hospital environment is understood to play an important role in the transmission of nosocomial pathogens, with inanimate surfaces facilitating pathogen movement and persistence in the environment. The majority of studies of surface contamination have been carried out in outbreak conditions or on high-dependency wards. Current surface cleaning guidance only requires surfaces to be visually clean. Microbiological standards for cleanliness have been proposed, however they are not widely adopted, and little implementation guidance is available. Evidence-based surface sampling protocols are required for the transmission risk surfaces pose to be adequately quantified and addressed.MethodsEnvironmental surface samples will be collected in a number of in- and outpatient settings, staff, and public areas, such as waiting rooms. This will be done before and after cleaning. Pathogens associated with nosocomial infection (e.g., ESKAPE pathogens, Clostridioides difficile and Candida auris) will be identified through culture methods and MALDI-ToF mass spectrometry. Antimicrobial susceptibility profiles of isolates will be determined following EUCAST protocols. Real-time PCR will be utilized to identify viral pathogens (including norovirus, adenovirus, influenza and SARS-CoV-2) present. Following this, samples will be collected for community composition sequencing, allowing for non-culturable microorganisms to be identified. Whole genome sequencing will be performed on any pathogens of interest isolated during this investigation.Results and ConclusionFewer microorganisms are expected to be isolated after cleaning than prior, and samples from in-patient environments will have higher proportions of pathogens. The hospital microbiome has rarely been investigated outside of outbreak conditions. This study presents a novel, systematic approach to assess the microorganisms present in the hospital environment, and how they are impacted by current cleaning measures. This will build a comprehensive picture of the hospital microflora and provide an evidence base for the development of surface sampling protocols, helping inform clinical risk assessments and subsequently improving patient outcomes.