COVID-19 Innovations: Ford Cars And Ohio State University Explores Using Heat Treatments To Inactivate SARS-CoV-2 In Passenger Vehicles
: Scientist from Ohio State University along with researchers from the Ford Research and Innovation Center-Michigan have in a new study explored the use of heat treatments to inactivate SARS-CoV-2 in passenger vehicles including cars, van and buses.
According to the study abstract, “Heat is an established method to inactivate coronaviruses, and there is utility in using heat to reduce viral load on common touch points in vehicles exposed to a person shedding SARS-CoV-2. As SARS-CoV-2 is a Biosafety level (BSL)-3 pathogen, real world testing of heat as a sanitation method for public and private vehicles becomes a challenge, requiring a surrogate coronavirus that can be handled safely outside of a BSL-3 facility. “
The study team used Bovine Coronavirus (BCoV) as a surrogate for SARS-CoV-2 to test the efficacy of heat-based betacoronavirus inactivation.
The study findings showed that in vitro
, a 30-minute exposure to 56°C completely inactivated BCoV in solution, and a 15-minute exposure reduced recovery of BCoV >1000-fold. When heated to 56°C for 15 minutes, the infectivity of BCoV spotted and dried on typical porous and non-porous automobile interior materials was reduced by 99 - 99.99%. When BCoV was spotted and dried on hard plastic (seat) material placed inside an out of service transit bus, 56°C heat for 30 minutes reduced BCoV infectivity 85 - 99.5%. Thus, 56°C is an accessible, rapid, and effective method to inactivate coronaviruses inside motor vehicles.
The study findings were published on a preprint server and are currently being peer reviewed. https://www.biorxiv.org/content/10.1101/2021.09.08.459486v1
It has already been known that heat exposure can effectively inactivate the SARS-CoV-2 coronavirus, the causative agent of coronavirus disease 2019 (COVID-19), similar to other viruses.
Hence common touchpoints in private and public vehicles can receive heat treatment as a form of sanitization to kill heat-sensitive viruses, such as SARS-CoV-2.
The study was part of FORD cars’ COVID-19 Innovations
initiative to find more solutions to aid the control of the pandemic.
Such forms of sanitization can be performed routinely with general cleaning or as a sanitization protocol following exposure from an infected person.
The SARS-CoV-2 virus is persistent in dust in indoor settings by environmental surveillance. Several studies have demonstrated that atmospheric air and surfaces of public vehicles are commonly contaminated with SARS-CoV-2 particles.
The study team investigated if heat inactivation treatment was a viable form of sanitization for high-touch materials commonly located on public and private transport vehicles.
Due to SARS-CoV-2 having a classification of Biosafety level (BSL) 3, it cannot be tested in field studies, so the study team decided to use Bovine Coronavirus (BCoV) as a substitute.
In a past study, BCoV has been utilized as a substitute for Middle Eastern Respiratory Syndrom
e (MERS) and SARS, both of which are of the Coronaviridae
family, as are SARS-CoV-2 and BCoV.
The vehicle surfaces deemed highpoint included gear shift knob, door handles, turn and wiper levers, steering wheel, buttons and touchscreens, grab handles, armrests, seat upholstery, belts, cup holders, seat adjustments, console bins, and seat backs.
The vehicle surfaces selected for the experiment comprised various materials, so one cm2
sample of each material was used for the procedure. In triplicate, each sample piece was placed into a single well of a 12-well dish.
The study team performed six experiments, and throughout these procedures, an average of 2.7x106
units of BCoV-Mebus was added to each sample as a single drop. The samples containing the virus were placed in a humidity-controlled incubator set to 55% relative humidity and 56°C.
Furthermore the hard plastic obtained from the seats was cut into one cm2
coupons, placed into single wells of a 12-well dish, and had an average of 2x106
added via single drops. These samples were placed inside a bus in various locations, and via a gas heater, the bus was heated to 56°C.
In order to test the effectiveness of 56°C on BCoV infectivity, the study team incubated a solution of 3.64x105
units of BCoV in MEM for 0, 15, 20, 30, and 60 minutes.
The study findings showed that when compared to unheated samples of BCoV, virus samples that had been heated at 56°C for 15 minutes showed reduced infectivity by over 1000-fold. The authors could not retrieve any viable infectious BCoV from the samples heated for 30 or 60 minutes.
Interestingly the study findings from the samples placed on the bus varied with the position in which they were situated. The samples placed towards the front of the bus showed a reduction in virus content by 99.5%, and the samples from the middle and towards the back of the bus displayed a reduction in virus content by 85%
The study findings show that 56°C of heat is an inexpensive, effective, and efficient method that could be utilized to sanitize common touchpoints on privately and publicly used vehicles. Due to heat being widely available in vehicles, relatively safe, and practical, it should be a method that is considered for virus inactivation for enclosed spaces in vehicles.
Ford cars are development platforms whereby these study findings can be incorporated into their vehicles, service centers, community car repair centers and fuel replenishing centers.
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