What They Say
The US Centers for Disease Control have published new guidance on the use of touch screens that reports that there is less than a 1 in 10,000 chance of getting an infection from each touch on a surface. On non-porous surfaces, the virus will decay slowly, with a 99% reduction after three days, even without any cleaning and regardless of the type of cleaning.
Cleaning can reduce the risk of transmission, although there are no reported studies of surfaces cleaned with soap or detergent without a disinfectant for Covid, although other microbes are typically reduced by 90% to 99.9%. Cleaning, though, can damage the surface of the virus. To ‘substantially’ inactivate the virus, a disinfectant needs to be used. The report said that:
“…there is little scientific support for routine use of disinfectants in community settings, whether indoor or outdoor, to prevent SARS-CoV-2 transmission…”
However, the advice said that routine cleaning performed effectively with soap or detergent, at least once per day, can substantially reduce virus levels on surfaces, where there hasn’t been a suspected or confirmed case indoors.
Concentrations of infectious virus 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. Hand hygiene should also reduce the risk of transmission from contaminated surfaces.
What We Think
While the 1 in 10,000 chance has been widely reported, I couldn’t help noting that this was ‘per contact’. In other words, a relatively complex set of interactions would reduce that probability. That is to say, if a process, such as buying a train ticket or making a full fast food order took 10 touches, the probability reduces to 1 in 1,000.
However, it is good news that a daily cleaning regimen would go a long way to reduce the probability of transmission. (BR)
