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 one to two hours )”.
As Goldman ( 2020 ) explains , “ The longest survival ( six days ) of severe acute respiratory syndrome coronavirus ( SARS-CoV ) on surfaces was done by placing a very large initial virus titer sample ( 107 infectious virus particles ) on the surface being tested . Another study that claimed survival of four days used a similarly large sample ( 106 infectious virus particles ) on the surface . A report by van Doremalen , et al . found survival of both SARS-CoV and SARS-CoV-2 of up to two days ( on surfaces ) and three 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 ). Yet another study found long survival ( five days ) of human coronavirus 229E on surfaces with a substantially large viral load ( 103 plaque-forming units ) in a cell lysate . However , using a cell lysate rather than purified or semi-purified virus might enable initial viral proliferation or protection from the effects of the sample drying out . None of these studies presents 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 . By contrast , one study found human coronavirus 229E to survive for only three to six hours ( depending on the surface tested ), and human coronavirus OC43 to survive for one hour , after drying on various surfaces including aluminum , sterile latex surgical gloves , and sterile sponges .”
The researcher also points to a recent literature review ( Kampf , et al . 2020 ) that he says does not critically evaluate previously published studies : “ For example , in the studies that used a sample of 107 , 106 , and 104 particles of infectious virus on a small surface area , 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 . Hence , a real-life situation is better represented in the work of Dowell and colleagues in which no viable virus was found on fomites .”
As Goldman ( 2020 ) notes further , “ 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 one to two hours ). 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 .”
Commenting on the points made by Goldman ( 2020 ) are Mondelli , et al . ( 2020 ), who conducted two sequential studies seeking to determine the extent , if any , of contamination of inanimate surfaces in a standard infectious disease ward of a major referral hospital , as well as whether the risk of contamination was higher in emergency rooms and sub-intensive care wards than on ordinary wards . As the researchers explained , “ Cleaning procedures were standard . A number of objects and surfaces were swabbed . Remarkably , only the continuous positive airway pressure helmet of one patient was positive for SARS-CoV-2 RNA . More importantly , attempts to culture the positive swabs on Vero E6 cells were unsuccessful , suggesting that patient fomites and surfaces are not contaminated with viable virus . Our findings suggest that environmental contamination leading to SARS-CoV-2 transmission is unlikely to occur in real-life conditions , provided that standard cleaning procedures and precautions are enforced . These data would support Goldman ’ s point that the chance of transmission through inanimate surfaces is less frequent than hitherto recognized .”
Weber and Stilianakis ( 2020 ) agree with Goldman ’ s conclusion that fomite transmission is an unlikely transmission route for enveloped respiratory viruses such as SARS-CoV-2 ( or influenza ), but they also assert that virus inactivation on human skin is “ a more likely bottleneck limiting fomite transmission risk than the quantity of virus deposited on environmental surfaces .” As Weber and Stilianakis ( 2020 ) explain , “ Fomite transmission pathways of respiratory viruses — transfer from source host to environmental surfaces by talking , coughing , or sneezing ; the subsequent transfer of virus from the surface to the hand or other body part of the recipient host ; and finally , the transfer to the recipient host ’ s mucous membranes — have been studied to a limited extend experimentally . Most such studies do not analyze the full transmission pathway but focus primarily on the detection of virus on surfaces in indoor environments .”
As we know , estimates of the viral dose transmitted from environmental surfaces to mucous membranes are analyzed by using quantitative microbial risk assessment models ( Nicas and Best , 2008 ). Because the types and frequencies of human activities and the diversity of environmental surfaces differ between settings , experts tell us that social and environmental context are critical when assessing the infection-risk-through-fomite mode of transmission . Studies conducted by Beamer , et al . ( 2015 ) and Contreras , et al . ( 2020 ) assume realistic rates of virus-shedding and deposition on surfaces , thereby addressing Goldman ( 2020 )’ s objections to the conclusions drawn from experimental studies of the inactivation of large virus inocula on surfaces .
Whereas Contreras , et al . ( 2020 ) only consider the risk of infection from fomite transmission , other quantitative microbial