Exaggerated risk of transmission of COVID-19 by fomites
Authors: Emanuel Goldman
Journal: The Lancet Infectious Diseases (2020)

A clinically significant risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission by fomites (inanimate surfaces or objects) has been assumed on the basis of studies that have little resemblance to real-life scenarios. The longest survival (6 days) of severe acute respiratory syndrome coronavirus (SARS-CoV) on surfaces was done by placing a very large initial virus titre sample (107 infectious virus particles) on the surface being tested.1Rabenau HF Cinatl J Morgenstern B Bauer G Preiser W Doerr HW Stability and inactivation of SARS coronavirus.Med Microbiol Immunol. 2005; 194: 1-6Crossref PubMed Scopus (428) Google Scholar Another study that claimed survival of 4 days used a similarly large sample (106 infectious virus particles) on the surface.2Duan SM Zhao XS Wen RF Huang JJ Pi GH Zhang SX Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation.Biomed Environ Sci. 2003; 16: 246-255PubMed Google Scholar A report by van Doremalen and colleagues found survival of both SARS-CoV and SARS-CoV-2 of up to 2 days (on surfaces) and 3 days (in aerosols generated in the laboratory), but again with a large inoculum (105–107 infectious virus particles per mL in aerosols, 104 infectious virus particles on surfaces).3van Doremalen N Bushmaker T Morris DH et al.Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1.N Engl J Med. 2020; 382: 1564-1567Crossref PubMed Scopus (6695) Google Scholar Yet another study found long survival (5 days) of human coronavirus 229E on surfaces with what I would still consider a substantially large viral load (103 plaque-forming units) in a cell lysate.4Warnes SL Little ZR Keevil CW Human coronavirus 229E remains infectious on common touch surface materials.mBio. 2015; 6: e01697-e01715Crossref PubMed Scopus (375) Google Scholar However, using a cell lysate rather than purified or semipurified virus might enable initial viral proliferation or protection from the effects of the sample drying out. None of these studies present scenarios akin to real-life situations. Although I did not find measurements of coronavirus quantities in aerosol droplets from patients, the amount of influenza virus RNA in aerosols has been measured, with a concentration equivalent to 10–100 viral particles in a droplet, with even fewer infectious influenza virus particles capable of growth in a plaque assay.5Lindsley WG Blachere FM Thewlis RE et al.Measurements of airborne influenza virus in aerosol particles from human coughs.PLoS One. 2010; 5e15100Crossref PubMed Scopus (328) Google Scholar By contrast, one study found human coronavirus 229E to survive for only 3–6 h (depending on the surface tested), and human coronavirus OC43 to survive for 1 h, after drying on various surfaces including aluminum, sterile latex surgical gloves, and sterile sponges.6Sizun J Yu MW Talbot PJ Survival of human coronaviruses 229E and OC43 in suspension and after drying on surfaces: a possible source of hospital-acquired infections.J Hosp Infect. 2000; 46: 55-60Summary Full Text PDF PubMed Scopus (217) Google Scholar In a study in which the authors tried to mimic actual conditions in which a surface might be contaminated by a patient, no viable SARS-CoV was detected on surfaces.7Dowell SF Simmerman JM Erdman DD et al.Severe acute respiratory syndrome coronavirus on hospital surfaces.Clin Infect Dis. 2004; 39: 652-657Crossref PubMed Scopus (154) Google Scholar A 2020 literature review8Kampf G Todt D Pfaender S Steinmann E Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents.J Hosp Infect. 2020; 104: 246-251Summary Full Text Full Text PDF PubMed Scopus (2518) Google Scholar included most of the studies I have cited here (and others), but adds no new research, and in my view, does not critically evaluate previously published studies. I am not disputing the findings of these studies, only the applicability to real life. For example, in the studies that used a sample of 107, 106, and 104 particles of infectious virus on a small surface area,1Rabenau HF Cinatl J Morgenstern B Bauer G Preiser W Doerr HW Stability and inactivation of SARS coronavirus.Med Microbiol Immunol. 2005; 194: 1-6Crossref PubMed Scopus (428) Google Scholar, 2Duan SM Zhao XS Wen RF Huang JJ Pi GH Zhang SX Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation.Biomed Environ Sci. 2003; 16: 246-255PubMed Google Scholar, 3van Doremalen N Bushmaker T Morris DH et al.Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1.N Engl J Med. 2020; 382: 1564-1567Crossref PubMed Scopus (6695) Google Scholar these concentrations are a lot higher than those in droplets in real-life situations, with the amount of virus actually deposited on surfaces likely to be several orders of magnitude smaller.5Lindsley WG Blachere FM Thewlis RE et al.Measurements of airborne influenza virus in aerosol particles from human coughs.PLoS One. 2010; 5e15100Crossref PubMed Scopus (328) Google Scholar Hence, a real-life situation is better represented in the work of Dowell and colleagues7Dowell SF Simmerman JM Erdman DD et al.Severe acute respiratory syndrome coronavirus on hospital surfaces.Clin Infect Dis. 2004; 39: 652-657Crossref PubMed Scopus (154) Google Scholar in which no viable virus was found on fomites. In my opinion, the chance of transmission through inanimate surfaces is very small, and only in instances where an infected person coughs or sneezes on the surface, and someone else touches that surface soon after the cough or sneeze (within 1–2 h). I do not disagree with erring on the side of caution, but this can go to extremes not justified by the data. Although periodically disinfecting surfaces and use of gloves are reasonable precautions especially in hospitals, I believe that fomites that have not been in contact with an infected carrier for many hours do not pose a measurable risk of transmission in non-hospital settings. A more balanced perspective is needed to curb excesses that become counterproductive. This online publication has been corrected. The corrected version first appeared at thelancet.com/infection on July 30, 2020 This online publication has been corrected. The corrected version first appeared at thelancet.com/infection on July 30, 2020 I declare no competing interests. Correction to Lancet Infect Dis 2020; 20: 892–93Goldman E. Exaggerated risk of transmission of COVID-19 by fomites. Lancet Infect Dis 2020; 20: 892–93—In this Comment, the third sentence of the third paragraph should have said "By contrast, one study found human coronavirus 229E to survive for only 3–6 h (depending on the surface tested)…". This correction has been made to the online version as of July 30, 2020. Full-Text PDF Low risk of SARS-CoV-2 transmission by fomites in real-life conditionsWe read with interest the Comment by Emanuel Goldman1 highlighting experiments done under controlled laboratory conditions that suggest persistence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on inanimate surfaces for days, with potential implications for viral transmission.2 Yet, at the same time, Goldman laments the absence of real-life studies investigating the infectious potential of SARS-CoV-2 on contaminated inanimate material and patient fomites, particularly in high-risk hospital wards. Full-Text PDF