An evaluation of the risk of airborne transmission of COVID-19 on an inter-city train carriage.

Experiments were conducted in an UK inter-city train carriage with the aim of evaluating the risk of infection to the SARS-CoV-2 virus via airborne transmission. The experiments included in-service CO2 measurements and the measurement of salt aerosol concentrations released within the carriage. Computational fluid dynamics simulations of the carriage airflow were also used to visualise the airflow patterns, and the efficacy of the HVAC filter material was tested in a laboratory. Assuming an infectious person is present, the risk of infection for a 1-h train journey was estimated to be 6 times lower than for a full day in a well-ventilated office, or 10-12 times lower than a full day in a poorly ventilated office. While the absolute risk for a typical journey is likely low, in the case where a particularly infectious individual is on-board, there is the potential for a number of secondary infections to occur during a 1-h journey. Every effort should therefore be made to minimize the risk of airborne infection within these carriages. Recommendations are also given for the use of CO2 sensors for the evaluation of the risk of airborne transmission on train carriages.

Discontinuation of Antihypertensive Medications on the Outcome of Hospitalized Patients With Severe Acute Respiratory Syndrome-Coronavirus 2.

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The dynamics in applied COVID-19 pharmacotherapy and the influence of national guidance in The Netherlands: a quantitative and qualitative study.

OBJECTIVE: At the beginning of the COVID-19 pandemic in the Netherlands, the Dutch Working Party on Antibiotic Policy constructed an advisory document about off-label drug treatment options that was regularly updated with new scientific findings. The aim of this study is to describe the dynamics in applied COVID-19 pharmacotherapy during the first 100 days of the pandemic and to assess how the national advisory document influenced local hospital policies. METHODS: A multicentre observational cohort study was conducted in six hospitals in the Netherlands. Patients with confirmed COVID-19 admitted between 27 February and 7 June 2020 were studied. Drug prescription data were collected and percentages of patients receiving a specific treatment were calculated. These percentages were plotted together with release dates of the national advisory document. Semi-structured in-depth interviews with hospital pharmacists and infectious diseases specialists were conducted to gain insight into the development and implementation of pharmacotherapy treatment protocols in hospitals. RESULTS: Data from 1511 patients (60% men, mean age 66 years) were analysed. From mid-March (hydroxy)chloroquine was being prescribed in all six hospitals to approximately 70% of patients at admission. Frequencies of other off-label treatments were below 2%. In the week of 6 April 2020, the first hospital discontinued prescribing (hydroxy)chloroquine and the last hospital discontinued in the week of 4 May 2020 (total range -19 to +10 days after the national advisory document advised against its use (1 May 2020)). All interviewees (n=6) stated that the hospitals based their policies mainly on the national advisory document but also assessed scientific literature themselves. Order panels were constructed to support prescribing. CONCLUSION: Dutch hospitals opted en masse for (hydroxy)chloroquine as COVID-19 therapy at the start of the pandemic, although the time until the therapy was no longer prescribed differed by several weeks. The fact that hospitals defined pharmacotherapy regimens based on their own assessment of the scientific literature besides the national advisory document can explain this variation.

Numerical study of COVID-19 spatial-temporal spreading in London.

A recent study reported that an aerosolized virus (COVID-19) can survive in the air for a few hours. It is highly possible that people get infected with the disease by breathing and contact with items contaminated by the aerosolized virus. However, the aerosolized virus transmission and trajectories in various meteorological environments remain unclear. This paper has investigated the movement of aerosolized viruses from a high concentration source across a dense urban area. The case study looks at the highly air polluted areas of London: University College Hospital (UCH) and King's Cross and St Pancras International Station (KCSPI). We explored the spread and decay of COVID-19 released from the hospital and railway stations with the prescribed meteorological conditions. The study has three key findings: the primary result is that the concentration of viruses decreases rapidly by a factor of 2-3 near the sources although the virus may travel from meters up to hundreds of meters from the source location for certain meteorological conditions. The secondary finding shows viruses released into the atmosphere from entry and exit points at KCSPI remain trapped within a small radial distance of < 50 m. This strengthens the case for the use of face coverings to reduce the infection rate. The final finding shows that there are different levels of risk at various door locations for UCH; depending on which door is used there can be a higher concentration of COVID-19. Although our results are based on London, since the fundamental knowledge processes are the same, our study can be further extended to other locations (especially the highly air polluted areas) in the world.

Seasonal variation in airborne infection risk in schools due to changes in ventilation inferred from monitored carbon dioxide.

The year 2020 has seen the world gripped by the effects of the COVID-19 pandemic. It is not the first time, nor will it be last, that our increasingly globalized world has been significantly affected by the emergence of a new disease. In much of the Northern Hemisphere, the academic year begins in September, and for many countries, September 2020 marked the return to full schooling after some period of enforced closure due to COVID-19. In this paper, we focus on the airborne spread of disease and investigate the likelihood of transmission in school environments. It is crucial to understand the risk airborne infection from COVID-19 might pose to pupils, teachers, and their wider social groups. We use monitored CO2 data from 45 classrooms in 11 different schools from within the UK to estimate the likelihood of infection occurring within classrooms regularly attended by the same staff and pupils. We determine estimates of the number of secondary infections arising via the airborne route over pre/asymptomatic periods on a rolling basis. Results show that, assuming relatively quiet desk-based work, the number of secondary infections is likely to remain reassuringly below unity; however, it can vary widely between classrooms of the same school even when the same ventilation system is present. Crucially, the data highlight significant variation with the seasons with January being nearly twice as risky as July. We show that such seasonal variations in risk due to changes in ventilation rates are robust and our results hold for wide variations in disease parameterizations, suggesting our results may be applied to a number of different airborne diseases.

Celebrating George K. Batchelor's Centenary

Mark Hallworth. Reproduced with Permission.