Surface Survival of SARS-CoV-2

Seriously, how long can this thing survive on surfaces?

In an earlier post, I referenced some preliminary research suggesting that SARS-CoV-2, the virus that causes COVID-19, can live in the air and on surfaces between several hours and several days. This work, originally released as a pre-print and recently finalized and published in the New England Journal of Medicine, found the virus is viable for up to 4 hours on copper, 24 hours on cardboard, 48 hours on stainless steel, 72 hours on plastics, and is also detectable in the air for 3 hours. 

A lot of posts present this information out of context and headlines can make it sound frightening, “SARS-CoV-2 Lives on Plastic for 72 Hours!!!” However, what’s more important is the amount of virus that’s still alive. It’s <0.1% of what the investigators started with. So, infection is theoretically possible but extremely unlikely at the levels they saw after a few days. 

Another important thing to mention lies in the experimental design of the aerosol component of the study. It has some caveats. They found that the virus can be detected in the air for 3 hours in the lab. However, in nature, respiratory droplets fall to the ground at a faster speed than the aerosols generated in their experiments. This is because the lab-generated aerosols are smaller (<5 μm) than what is produced from a cough or sneeze, so they remain in the air at face-height longer than the natural, heavier particles. It’s not a perfect comparison (though science rarely is, we just do our best). The size of these particles can affect how they move through the air and how they impact a surface. 

So, at the end of the day you’re more likely to become infected through the air if you’re next to an infected person versus a contaminated surface. Make sure you clean surfaces with disinfectant or soap – they work because they disturb the oily external layer of the virus keeping it from infecting your cells. 

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