SARS-Co-V2 and Fomite Contamination and Clinical Risk : Real-World vs . Controlled Environments
By Kelly M . Pyrek
Any current conversation regarding surface cleaning and disinfection in healthcare facilities is taking place within the context of the potential / presumed presence of SARS-CoV-2 and its transmission route ( s ). Pathogens of importance in the healthcare environment are dissected for their etiology , mechanisms for spread , and interventions to halt infection , and for the virus that is responsible for COVID-19 , a quick review of viral persistence on fomites is in order .
As Boone and Gerba ( 2007 ) remind us , “ The potential for a virus to be spread via contaminated fomite depends first on the ability of the virus to maintain infectivity while on the fomite surface . Viruses are obligate parasites ; therefore , the level of viral infectivity on a fomite can only decrease over time . Several studies have demonstrated that viruses can remain infective on surfaces for different time periods . The length of time a virus remains viable depends on a number of complex variables . Viral survival may increase or decrease with the number of microbes present on a surface . Increasing amounts of microbes can protect viruses from desiccation and disinfection , but deleterious effects may also result from microbial proteases and fungal enzymes . Typically , viral presence on fomites may decrease with surface cleanliness and increase with surface usage . However , some cleaning products or disinfectants are ineffective against viruses and can result in viral spread or cross-contamination of surfaces . Easily measured and predictable factors that influence viral survival on surfaces include fomite properties , initial viral titer , virus strain , temperature , humidity , and suspending medium . Intrinsic factors , like fomite properties , virus strain , and viral inoculation titer , consistently impact the total virus survival end point ( hours , days ) … Extrinsic environmental factors , such as temperature , humidity , and surrounding viral medium , have a varying effect
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... there are numerous factors that impact viral persistence on fomites , particularly in the real-world healthcare environment , as opposed to far more controlled laboratory and other study environments . on viral decay rate , depending on the viral strain .”
In short , there are numerous factors that impact viral persistence on fomites , particularly in the real-world healthcare environment , as opposed to far more controlled laboratory and other study environments . As Meyerowitz , et al . ( 2020 ) note , “ Transmission of severe acute respiratory syndrome coronavirus 2 ( SARS-CoV-2 ), which causes coronavirus disease 2019 ( COVID-19 ), requires that a minimum but as yet unknown dose of replication-competent virus be delivered to a vulnerable anatomical site in a susceptible host . A combination of viral , host , and environmental characteristics affect transmission .”
The COVID-19 pandemic has placed new emphasis on environmental hygiene , with the assumption that transmission of SARS-CoV-2 by fomites is a significant clinical risk . One researcher , however , believes this assumption is flawed — especially if based on studies that have little resemblance to real-life scenarios .
While Goldman ( 2020 ) does not dispute the findings of this body of research , he asserts that they have very little applicability to the real world ; for example , he points to one study in which “ the authors tried to mimic actual conditions in which a surface might be contaminated by a patient , but no viable SARS-CoV was detected on surfaces .”