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COVID-19 transmission following outpatient endoscopy during pandemic acceleration phase involving SARS-CoV-2 VOC 202012/01 variant in UK
  1. Bu'Hussain Hayee1,
  2. The SCOTS II Project group,
  3. Pradeep Bhandari2,
  4. Colin J Rees3,
  5. Ian Penman4
    1. 1 Gastroenterology, King's College Hospital NHS Foundation Trust, London, UK
    2. 2 Gastroenterology, Queen Alexandra Hospital, Portsmouth, Portsmouth, UK
    3. 3 Gastroenterology, South Tyneside NHS Foundation Trust, South Shields, South Tyneside, UK
    4. 4 Centre for Liver & Digestive Disorders, Royal Infirmary of Edinburgh, Edinburgh, UK
    1. Correspondence to Dr Bu'Hussain Hayee, Gastroenterology, King's College Hospital NHS Foundation Trust, London, London, UK; b.hayee{at}

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    Infection prevention and control (IPC) measures put in place during the first phases of the COVID-19 pandemic were effective in reducing endoscopy-related transmission while allowing recovery of activity.

    In late 2020 a novel, more infectious, SARS-CoV-2 variant (VOC 202012/01) was associated with a second ’surge' or acceleration phase in the UK. We sought to measure whether pre-existing IPC guidance would be sufficient to prevent transmission in this scenario. Prospective data were collected from eight UK centres for n=2440 procedures. Pre-endoscopy, nine (0.37%) asymptomatic patients were positive for SARS-CoV-2 by nasopharyngeal swab (NPS) testing and their procedures deferred. Post endoscopy, 30 (1.27%) developed symptoms suspicious for COVID-19, with 15 (0.65%) testing positive on NPS. Three (0.12%) cases were attributed to potential transmission from endoscopy attendance. All 15 patients recovered fully requiring only community treatment.

    Although we report cases potentially transmitted by endoscopy attendance in this latest study, the risk of COVID-19 transmission following outpatient endoscopy remains very low. Thus, IPC measures developed in earlier pandemic phases appear robust, but our data emphasise the need for vigilance and strict adherence to these measures in order to optimally protect both patients and staff.

    In more detail

    The effects of the COVID-19 pandemic continue to extend beyond direct care of affected patients,1 particularly impacting outpatient diagnostics including GI endoscopy. Considerable concerns remain around the potential impact on detection of, and survival from, significant disease such as cancer.2 3 In mid-2020, a pandemic deceleration phase4 in the UK led to a period of intense ‘restart and recovery’ activity in endoscopy to mitigate the effects of delayed or cancelled procedures. This was supported by professional society guidance on the development of ‘COVID-minimised’ or ‘green’ pathways with NPS testing of patients before their attendance for the procedure.5–7 Activity was limited by the impact on endoscopy staff and resources, but additionally by patient concerns regarding the risk of transmission by attending hospital; a complex and multifactorial challenge.8 9 A multicentre study of COVID-19 transmission following outpatient endoscopy in the deceleration phase (when community infection rates were low) demonstrated that, with appropriate IPC measures in place,5 10 there were no recorded cases of transmission in over 6200 patients.11

    In early December 2020, the effect of a new SARS-Cov-2 variant (termed VOC 202012/01) was associated with an acceleration phase in southeast England.12 13 Pre-existing IPC measures had been developed to facilitate safe endoscopy during a pandemic deceleration or recovery phase (with relatively low rates of community infection).7 These comprised telephone screening for COVID-19 symptoms; pre-procedure NPS testing (even in asymptomatic individuals); separation of pathways according to perceived or actual transmission risk and the potential for aerosol generation. Furthermore, a variety of testing strategies, with varying levels of accuracy, have been employed across hospitals in the UK and internationally.14–16 Despite these concerns, the negative predictive value (NPV), even of an imperfect test, was felt to be sufficiently high to rely on NPS as a cornerstone of the ‘green’ pathway.7 As NPV is dependent on prevalence, we sought to determine whether IPC measures were sufficient to prevent COVID-19 transmission during an acceleration pandemic phase, with rising prevalence as well as a more infectious viral variant.

    This multicentre prospective study collected data from consecutive outpatients attending for elective diagnostic or therapeutic endoscopy from eight centres across southeast England. No patient identifiable data were collected, no treatment decisions were affected and no identifiable data were analysed or transferred. Review by the Research Governance committee at the lead author’s institution confirmed that ethical approval was not required. Participating centres were invited to submit data for the 3-week period 14–31 December 2020 inclusive, based on the identification of an acceleration phase as above, with rising community incidence in the areas served by those hospitals (at least 800 cases per 100 000 population per week; figure 1; compared with <10 per 100 000 in August 202013 17). These were three London tertiary care hospitals, two London secondary care hospitals and three secondary care hospitals in southeast England (the county of Kent adjacent to London).

    Figure 1

    Rolling-rate of new cases in the regions served by the hospitals participating in this study (as of 15 December 2020). Downloaded with permission from Ref. 13. Rates are per 100 000 population.

    All centres prospectively completed an anonymised database of patients including procedure type, responses to preprocedure criteria,7 preprocedural NPS result, source of referral and dates for all activities. All centres conducted patient follow-up by telephone consultation at 7 and 14 days after the procedure to check for symptoms of COVID-19. If symptoms were reported, all patients who had not already been tested based on their development of symptoms underwent NPS testing according to local or national protocols and the results were recorded. In all cases, regardless of NPS result, the outcome of symptoms was noted and, in cases testing positive for SARS-CoV-2, a root-cause analysis was performed by the reporting hospital to determine the most likely source of transmission. The mean incubation period for COVID-19 is understood to be around 5 days.18–20 In order to be attributed to transmission in the endoscopy unit, therefore, patients must have developed symptoms within 10 days of attendance and have no other more likely source of transmission identified on direct questioning by the local care team.

    Data were collected from n=2440 (48.8% female) patients undergoing diagnostic or therapeutic endoscopy (n=966 (39.6%) upper endoscopy; figure 2).

    Figure 2

    Proportions of procedures performed.

    Before endoscopy, 9/2449 (0.37%) asymptomatic patients were positive for SARS-CoV-2 and had their procedures deferred. These nine patients were not included in further analysis. After endoscopy, 30/2440 (1.27%) developed symptoms suspicious for COVID-19, with 16 (0.65%) testing positive on NPS. All cases recovered without the need for hospital admission. After analysis, there were three (0.12%) cases where no other likely source of transmission was identified, other than the attendance for endoscopy (table 1). There were no cases of transmission to staff members as a direct result of these cases. It was not possible to calculate overall rates of infection in staff as the number of staff in units was highly variable with significant rotation due to secondment or redeployment, but there were only six confirmed cases in staff members across all participating sites. Rates of staff absence varied considerably, with three hospitals (two tertiary and one secondary care) reporting no absence due to COVID-19 in the 3-week period of the study. One hospital reported absence of nearly 75% of its endoscopy staff due to two infected staff members (from community transmission), mandating isolation for the others while testing was performed. This was primarily due to uncertainty around adherence to IPC measures in a break room. No COVID-19 cases in either patients or staff required hospitalisation or additional treatment and all resolved without further event.

    Table 1

    Analysis of COVID-19 cases confirmed by nasopharyngeal swab (NPS) after symptom onset


    This multicentre prospective study of 2440 patients undertaken during a pandemic acceleration phase of a more infectious SARS-Cov-2 variant provides reassurance that GI endoscopy is associated with a very low risk of transmission for both patients and staff.

    While asymptomatic positive rates are higher than the previous study,11 the rate remains low, at less than 0.5%. The risk of acquiring COVID-19 from endoscopy continues to remain very low. However, it is important to acknowledge that this rate is not zero. This serves to emphasise the need for vigilance and strict adherence to the principle of a COVID-minimised pathway.

    The risk of missed or delayed cancer diagnosis would appear to significantly outweigh the risks of COVID-19 transmission. We believe these data should be of continued reassurance to healthcare providers and patients alike, facilitating the provision of much-needed endoscopy services.

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    • Collaborators The SCOTS II Project group comprises: Vivienne Sayer, Mayur Kumar, Kath Lynch Princess Royal University Hospital, Orpington, Kent; Ben Warner, Olaolu Olabintan Darenth Valley Hospital, Dartford, Kent; Imogen Sutherland, Gabor Sipos Medway Maritime Hospital, Gillingham, Kent; Zacharias Tsiamoulos Queen Elizabeth QM Hospital, Margate, Kent; Shraddha Gulati, Mehul Patel King’s College Hospital, London; Ed Seward, Rawen Kader University College London Hospital, London; Sergio Coda, Sas Banerjee Barking and Havering NHS Trust, London; Adam Humphries, Sarah Marshall, Angad Dhillon, Romanov Nable St Mark’s Hospital, London.

    • Contributors All named authors contributed to the initiation, analysis and writing of this article.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

    • Provenance and peer review Not commissioned; internally peer reviewed.