COVID-19: using chest CT of major trauma patients to monitor and evaluate the second wave in London and the development of routine monitoring in practice.

AIM: To follow-up previous work evaluating incidental findings of COVID-19 signs on computed tomography (CT) images of major trauma patients to include the second wave prior to any major effects from vaccines. MATERIALS AND METHODS: The study population included all patients admitted following major trauma between 1 January 2020 and 28 February 2021 with CT including the lungs (n=1776). Major trauma patients admitted pre-COVID-19 from alternate months from January 2019 to November 2019 comprised a control group (n=837). The assessing radiologists were blinded to the time period and used double reading in consensus to determine if the patient had signs of COVID-19. Lung appearances were classified as no evidence of COVID-19, minor signs, or major signs. RESULTS: The method successfully tracked the second wave of the COVID-19 pandemic in London. The estimated population affected by the disease based on those with major signs was similar to estimates of the proportion of the population in London with antibodies (around 30% by end February 2021) and the total of major and minor signs produced a much higher figure of 68%, which may include all those with both antibody and just T-cell responses. CONCLUSIONS: Incidental findings on CT from major trauma patients may provide a novel and sensitive way of tracking the virus. It is recommended that all major trauma units include a simple question on signs of COVID-19 to provide an early warning system for further waves.

COVID-19: using chest CT of major trauma patients to monitor and evaluate the effect of lockdown and the importance of household size.

AIM: To use theory and practice to show how disease progression and regression can be described pre- and post-lockdown using an attack-sustain-decline-respite (ASDR) model and investigate how pre-lockdown disease prevalence and household size impacts on the effectiveness of lockdown. MATERIALS AND METHODS: Computed tomography (CT) scans from major trauma patients (considered as a random population sample) from the radiology department of St George's University Hospitals NHS Trust, London, have been used to explore COVID-19 disease at the population level. RESULTS: At lockdown on 23 March 2020 in the catchment area of St George's University Hospitals NHS Trust, an earlier paper showed that there was a high prevalence of disease of >20%. With further follow-up and at the end of lockdown, it have been now estimated that around 57% of the population had been affected, which was similar to that predicted from a simple model based on average household size and prevalence at lockdown. With an average household size of around three persons, there was a 2-week sustain period and a 5-week decline period before the prevalence of the disease returned to background levels. CONCLUSIONS: The present results suggest that the effect of lockdown is dependent on the disease prevalence at the start of lockdown and the average household size. It may therefore be important to lockdown early in an area with a high average household size. This paper is the second in a series of papers to show how radiology measurements of major trauma patients can be used to help monitor the spread of the COVID-19 pandemic.

COVID-19: could CT provide the best population level biomarker? Incidental COVID-19 in major trauma patients suggests higher than predicted rates of infection in London.

AIM: To evaluate incidental findings in major trauma patients, and to explore whether computed tomography (CT) could be used to assess prevalence and estimate disease spread in the general population. MATERIALS AND METHODS: The study population included all patients admitted following major trauma between 1 January 2020 and 30 April 2020 with CT including the lungs (n=523). Major trauma patients admitted pre-COVID-19 from 1-31 January and 1-31 March 2019 comprised a control group (n=252). The assessing radiologists, blinded to the time period, used double reading with consensus to determine if the patient had CT signs of COVID-19. Lung appearances were classified as no evidence of COVID-19; minor signs; or major signs. The proportion of patients with incidental COVID-19 changes was recorded over the study period, and the percentage of the population who had been affected by COVID-19 by the end of April 2020 estimated. RESULTS: CT appearances consistent with COVID-19 began to exceed a background pre-COVID rate in the second week of February and did not decline until 2 weeks after lockdown. By the end of April 2020, approximately 45% of the population had been infected. CONCLUSIONS: CT of major trauma patients can be used to monitor the spread of COVID-19. This novel technique could be used retrospectively or prospectively anywhere where trauma scans are available, to monitor the disease in the local population.