Exaggerated risk of transmission of COVID-19 by fomites - The Lancet Infectious Diseases
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.1
Another study that claimed survival of 4 days used a similarly large sample (106 infectious virus particles) on the surface.2
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).3
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.4
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.