How Long Does the Novel Coronavirus Live on Surfaces

If you’re trapped at home like me, 

washing your hands for 20 seconds several times a day, 

and only occasionally going out to 

grab essential supplies in non-panic levels,

you’re doing your part to slow the virus’s spread,
and your actions will save lives.
You’re also probably like me and looking
at all the doorknobs in your house like

they’re out to get you.
So let’s address how long the virus can linger on surfaces（停留在表面）, 

and what you should be wiping down 

to keep yourself and others as safe as possible.
First off, let’s just say that the scientific
literature on the subject is pretty limited.
The novel coronavirus is just that: 
novel, new.
Its full name is SARS-CoV-2, and like all sequels(续集), 

it's worse than the original.
It’s taken the world by storm, and even though
it is a very pressing threat, scientific research
moves at a much slower pace.
It takes time to study it, have the results
peer reviewed（同行评审） and confirmed, and then published.
So some of this information is still in the pre-print phase, 

and may be changed or tweaked（调整）,
but I promise you it is much more rigorously（严格的） tested
than a lot of the information that’s flying
around on Facebook or Twitter.
One study from the National Institutes of Health 

that at the time we wrote this was
available in pre-print, examined how long the
virus can remain viable(能独立生存的) on a few common “fomites(传染媒介),”
or materials which can transmit the infection.
The fomites that were tested were copper,
stainless steel, cardboard, and one of the
most common plastics called polypropylene（聚丙烯）,
which is used to package food, for tote（大提包） bags,
and in many kitchen items.
The researchers found copper was the toughest
for the virus to survive on; four hours after
exposure they couldn’t find any that were
viable, or capable of infecting a person.
Cardboard was the next toughest for the virus,
with none found viable after 24 hours.
Stainless steel and plastic were much more
accommodating, with viable examples detected
even 72 hours after exposure.
But let’s mix in a little good news with the bad.
Just because there were viable viruses doesn’t
mean their concentration wasn’t dropping.
In fact the concentration dropped quite a bit, 

and it did so faster on the steel than on the plastic.
That’s because most viruses degrade outside
a living host, so while you can still get
infected by contacting a contaminated（受污染的） surface
days after the virus was deposited there,
it’s not as risky as within the first few
hours of contamination.
The study also examined how long the virus
can remain viable when suspended in aerosols（气雾剂; 气溶胶）.
The experiment lasted three hours, and the
virus remained viable the entire time, with
not much of a drop in concentration.
However, and I cannot stress this enough:
that does not mean the virus is “airborne（空气传播的）,”
like the virus that causes measles（麻疹）.
The researchers aerosolized this virus artificially
by spraying it into a mist and keeping it
aloft inside a special rotating（转动） drum.
In contrast, when an infected person exhales
or coughs, the virus is typically carried
in larger droplets, which do not stay suspended
in the air as long.
If droplets land on a person or a fomite,
then yes... that’s a problem.
But from what we know, the virus doesn’t
transmit like measles, which can stay infectious
in the air for half an hour or more.
Now, these are all results from tightly-controlled
laboratory settings.
In the real world, it’s possible the UV
light from sunshine disinfects surfaces faster.
It’s also possible that even though your
package was in transit for over 24 hours,
it was just sneezed on before it was left
at your door.
So don’t take these as hard and fast rules（可靠的规则、严格的制度）,
but more guidelines.
Hopefully what this information really does
is help make clear why you’ve been asked
to wash your hands frequently and avoid touching
your face and going out.
SARS-CoV-2 spreads most effectively from person to person.
If you touch surfaces you fear can be contaminated,
avoid touching your face because you can infect
yourself through your mouth, nose, and eyes.
Washing your hands thoroughly with soap destroys the virus.
As a bonus, soap micelles（微胶粒，微粒） also envelope the
fragments of viruses and carry them away,
which is what makes soap more effective than 

hand sanitizer（手部消毒剂;）.
Hand sanitizer and alcohol wipes are still
effective if they’re over 60% alcohol, so
go ahead and wipe down frequently touched
surfaces like door knobs, remotes, and light
switches daily.
And don't forget your phone, which touches
your hands and face a lot, 
so that should be wiped down often.
And most importantly: do not panic.
At a time like this, 
good information saves lives.
Stay safe, stay smart, and do your part.