THREAD: For the last few weeks there has been much speculation that the new coronavirus began as a lab accident in China. Today @emilykwong1234 and I dig into the science behind the claim:

https://www.npr.org/sections/goatsandsoda/2020/04/23/841729646/virus-researchers-cast-doubt-on-theory-of-coronavirus-lab-accident

tl;dr Scientists don't buy it.

The theory is that the virus may have accidentally leaked from a lab, namely the Wuhan Institute of Virology, which studies closely related bat viruses.

Intel agencies are investigating, according to reports like this one from @JennaMC_Laugh: https://news.yahoo.com/intelligence-officials-weigh-possibility-coronavirus-escaped-from-a-chinese-lab-194958353.html

But scientists who actually do this work have several problems with this theory, which has been promoted by Trump administration officials in recent weeks.

In fact none of the scientists interviewed by @NPR believed that a lab accident was the cause. Here's why.

First, to "release" the virus, scientists would have to find it in the wild. @DrSimonAnthony notes there are 1000s of coronaviruses circulating in bats. Most don't make people sick.

The chances that a random sample from a bat would catch such a deadly virus is relatively low.

Second, scientists are very careful when taking samples says @JonnaMazet. They where PPE including suits, gloves and masks when they take samples from bats.

They also plunge samples into liquid nitrogen as soon as they're taken, freezing any potential viruses.

Third, when researchers return to the lab, they don't work with live virus. They kill the virus samples with chemicals and work with just the genetic code.

They do keep a tiny sample of live virus in the fridge, but they're rarely able to revive it, even if they want to.

We know the Wuhan Institute follows these protocols, because U.S. scientists have been training them for years as part of the @PREDICTproject.

In fact, the institute actually helped develop these safety protocols, according to Mazet.