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SARS-COV-2 in endoscopy: still a long way to go
  1. Maria Valeria Matteo1,2,
  2. Ivo Boškoski1,2,
  3. Guido Costamagna1,2
  1. 1 Digestive Endoscopy Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma, Lazio, Italy
  2. 2 Centre for Endoscopic Research Therapeutics and Training (CERTT), Catholic University of Rome, Rome, Italy
  1. Correspondence to Dr Ivo Boškoski, Digestive Endoscopy Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma 00168, Italy; ivo.boskoski{at}

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We thank Chaussade et al that raised important questions regarding the potential ways of airborne transmission of microorganisms through endoscopes light source processors1 2 and their discussion on our previously published work on endoscopes used in positive and critically ill patients with SARS-CoV-2.2 Today we know that high viral loads on nasal and throat specimens characterise the early stage of COVID-19 disease, with viral load peaks during the first 7–10 days after symptoms onset and subsequent progressive decline over time.3–5 The dynamic of SARS-CoV2 infection is not yet completely understood but can be strongly influenced by clinical factors such as age, comorbidities, serological response and many other factors.5 For instance, elderly patients might have higher viral loads.5 Our analysis included 12 patients with moderate-to-severe COVID-19 disease and a mean age of 73 (53–93) years, who underwent a digestive or pulmonary endoscopic procedure after a mean time of 22.7 (IQR 9.75–32.5) days from symptoms onset or first positive PCR for SARS-CoV-2 on a nasopharyngeal swab. Notably, three patients underwent the procedure within 9 days from the diagnosis, while one patient had a positive swab 5 days after the endoscopic procedure.

Nevertheless, all swabs collected from the endoscopes immediately after the procedure were negative. Our pilot study aimed to validate the efficacy of high disinfection of endoscopes with peracetic acid (PAA) on eliminating SARS-CoV-2, based on the assumption that the endoscopes can be crucial in the transmission of SARS-CoV-2 due to the direct contact with mucosal surfaces. Surprisingly, the virus could not be detected on any part of endoscopes immediately after the procedure, regardless of the kind of procedure and scope used. Therefore, we could not validate the endoscope reprocessing with PAA, though we could postulate that the role of the endoscope as an infection vehicle is lower than we could expect. To our knowledge, no cases of direct SARS-CoV2 transmission related to infected endoscopes have been reported, even if this is difficult to verify.

Nevertheless, endoscopy in positive patients cannot be considered safe since infections are mainly related to an airborne viral transmission. The potential risk of SARS-CoV2 transmission described by Chaussade et al due to the environmental contamination derived from the circulation of air inside, from and to the light source processor is certainly not negligible. The primary aim of our study was the validation of the reprocessing method with PAA; thus, all microbiological tests were performed only on the endoscopes. However, the potential risk related to light source processor and environmental aerosolisation should be definitively further investigated, and not only for SARS-COV-2 but for all kind of micro-organisms. If a potential risk is confirmed, the development of modified ventilation systems suggested by Chaussade et al is undoubtedly advisable to reduce as much as possible the putative risk of viral spreading in the endoscopic room. The pandemic definitively opened many questions and problems, especially in endoscopy, and still, there is a long way to go before answers and solutions are given.

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  • Contributors IB: study conceptualisation, data curation and analysis; methodology, writing, reviewand editing. MVM: study conceptualisation, data curation and analysis; methodology, writing, reviewand editing. GC: study conceptualisation, data curation and analysis; methodology, writing, reviewand editing.

  • 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.

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