SARS Wars: The aerosols versus the fomites

Abstract

Early in the pandemic, there was great worry about SARS-CoV-2, the causative agent of COVID-19, spreading via fomites, that is inanimate surfaces and objects. People were disinfecting their mail, their groceries, and everything else, in the mistaken belief that this was the way to prevent transmission of the virus. In July 2020, I published online a Comment in Lancet Infectious Diseases challenging this presumption. The title of the Comment was "Exaggerated risk of transmission of COVID-19 by fomites". The crux of the argument was that the concentrations of virus used were way too high in experiments showing long survival of the virus on surfaces. Since the virus decays with a defined half-life, the more you start with, the more half-lives you have to go through before reaching an endpoint of less than one infectious virus particle on the surface. In other words, the experiments that were the basis for concern about fomite transmission of COVID-19 were unrelated to real-world conditions. It turns out to be even worse than I originally thought. Experiments recently published in Applied and Environmental Microbiology show that an enveloped virus, bacteriophage Phi6, protects itself from environmental decay at higher virus concentrations. Phi6 has been suggested for use as a non-pathogenic surrogate for SARS-CoV-2, which is also an enveloped virus. Therefore, the design flaw in experiments measuring surface survival of SARS-CoV-2 is not just that too much inoculum requires more half-lives to go through -- the larger inoculums extend the half-lives as well. The Lancet ID Comment was picked up by the press. A columnist from the Atlantic coined the term "hygiene theater" in an interview about the Lancet ID Comment. Other research corroborated the assertions in the Comment, and finally, Nature posted an editorial citing the Lancet ID Comment, calling on Public Health agencies to emphasize aerosols and stop warning about fomites. Nevertheless, publications continue to appear promoting fomite transmission as a risk. This article describes why these publications should not raise concern over the possibility of fomite transmission in the real world.