One QMRA study also evaluated the effectiveness of prevention measures that reduce the risk of fomite transmission and found that hand hygiene could substantially reduce the risk of SARS- CoV-2 transmission from contaminated surfaces , while surface disinfection once- or twiceper-day had little impact on reducing estimated risks .
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● The efficiency of transference of virus particles from fomite surfaces to hands and from hands to mucous membranes on the face ( nose , mouth , eyes )
● The dose of virus needed to cause infection through the mucous membrane route
As the CDC ( 2021 ) explains , “ Because of the many factors affecting the efficiency of environmental transmission , the relative risk of fomite transmission of SARS-CoV-2 is considered low compared with direct contact , droplet transmission , or airborne transmission . However , it is not clear what proportion of SARS-CoV-2 infections are acquired through surface transmission . There have been few reports of COVID-19 cases potentially attributed to fomite transmission . Infections can often be attributed to multiple transmission pathways . Fomite transmission is difficult to prove definitively , in part because respiratory transmission from asymptomatic people cannot be ruled out . Case reports indicate that SARS-CoV-2 is transmitted between people by touching surfaces an ill person has recently coughed or sneezed on , and then directly touching the mouth , nose , or eyes . Hand hygiene is a barrier to fomite transmission and has been associated with lower risk of infection .”
The CDC ( 2021 ) adds , “ Quantitative microbial risk assessment ( QMRA ) studies have been conducted to understand and characterize the relative risk of SARS-CoV-2 fomite transmission and evaluate the need for and effectiveness of prevention measures to reduce risk . Findings of these studies suggest that the risk of SARS-CoV-2 infection via the fomite transmission route is low , and generally less than 1 in 10,000 , which means that each contact with a contaminated surface has less than a 1 in 10,000 chance of causing an infection . Some studies estimated exposure risks primarily using outdoor environmental SARS-CoV-2 RNA quantification data . They noted that their QMRA estimates are subject to uncertainty that can be reduced with additional data to improve the accuracy and precision of information that is entered into the models . Concentrations of infectious SARS-CoV-2 on outdoor surfaces could be expected to be lower than indoor surfaces because of air dilution and movement , as well as harsher environmental conditions , such as sunlight . One QMRA study also evaluated the effectiveness of prevention measures that reduce the risk of fomite transmission and found that hand hygiene could substantially reduce the risk of SARS-CoV-2 transmission from contaminated surfaces , while surface disinfection once or twice per-day had little impact on reducing estimated risks .”
Goldman emphasizes , “ What is not sufficiently appreciated is that the virus is fragile and does not remain viable for very long outside of an infected person . Ordinary routine hygiene and cleanliness , and ordinary routine handwashing , is more than enough to eliminate even any possible miniscule risk of transmission by other routes than breathing .”
The temptation to conflate issues is irresistible by some in the mainstream media .
As Barber ( 2020 ) explains , “ It ’ s tempting to piece those two elements together : If the virus is on the surfaces around us , and it also lasts for a long time in lab settings , naturally we should vigorously disinfect . But that doesn ’ t necessarily reflect what ’ s happening . In a study published in Clinical Microbiology and Infection , researchers in Israel tried to piece it all together . They conducted lab studies , leaving samples out for days on various surfaces , and found they could culture the remaining virus in tissue . In other words , it remained infectious . Then they gathered samples from highly contaminated environments : COVID-19 isolation wards at a hospital , and at a hotel used for people in quarantine . The virus was abundant . But when they tried to culture those real-world samples , none were infectious . Later that month , researchers at an Italian hospital reported similar conclusions in The Lancet .”
As scientists debate the semantics around how to describe the “ airborne ” route of SARS-CoV-2 transmission , Barber ( 2020 ) acknowledges the problematic nature of what is usually conveyed in particles and droplets : “ In addition to environmental conditions , a confounding factor might be saliva , or the stuff that we often mean when we talk about droplets sticking onto surfaces . In her own research , [ Yale microbiologist Anne ] Wyllie has studied how long certain viral proteins remain intact in saliva to help determine the reliability of COVID-19 spit tests . For her purposes , stability is a good thing . But some proteins have appeared to denature more quickly than others , she notes , suggesting the virus as a whole does not remain intact and infectious . That could be because saliva tends to be less hospitable to pathogens than the synthetic substances or blood serums often used in lab-based stability studies .”
Barber ( 2020 ) adds , “ Consider , Wyllie says , the extraordinary chain of events that would need to happen to successfully spread SARS-CoV-2 on a surface . A sufficiently large amount of the virus would need to be sprayed by an infected person onto a surface . The surface would need to be the right kind of material , exposed to the right levels of light , temperature , and humidity so that the virus does not quickly degrade . Then the virus would need to be picked up — which you would most likely do with your hands . But the virus is vulnerable there . ( Enveloped viruses like SARS-CoV-2 do not fare well on porous surfaces like skin and clothing .) And then it needs to find a way inside you — usually through your nose or your eye — in a concentration big enough to get past your mucosal defenses and establish itself in your cells . The risk , Wyllie concludes , is low .”
Again , the scenario changes when considering the healthcare setting and high-touch surfaces and objects that warrant proper cleaning and disinfection – a critical way to break the chain of infection , particularly the surface / hand-carriage-to-nasal cavity route that can also be addressed through hand hygiene .
But the hygiene theater continues , particularly where socio-political debates are taking place over lockdowns and other questionable interventions ( see Escandon , et al ., 2021 relating to false COVID-19 dichotomies ). Barber ( 2020 ) quotes Princeton researcher Dylan Morris as commenting , “ I think that one thing that has been tough about this pandemic is there has been such a strong initial message that gave people the wrong intuition . For some people , and especially for institutions that were trying to reopen , liable to employees and visitors , priorities had been set based on what we knew back in the spring . It was also a way to show that they were doing something .”