Thread by @WIRED

There are a lot of questions health workers have about #COVID19. Who’s sick? How bad? How fast will the disease spread?

In the United States, no one has good answers, for one simple but terrifying reason: There aren’t enough tests. Here's why: 1/ wired.trib.al/FNGJOfk

First: The testing technology actually exists and is relatively simple. But for the first few months of the pandemic, there was a test kit shortage in the US. Health workers couldn’t test everyone who thought they might have #Covid19. 2/

On March 13, the first two commercial tests for #Covid19 received approval from the FDA. The companies plan to rapidly produce millions of these tests. But there still won't be enough of them to immediately meet the testing need. 3/

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As of Monday, the United States only had the ability to process about 37,000 tests per day. (That’s for a nation that has some 330 million people.) 4/

So how’d we get here? When federal health authorities declared #Covid19 a public health emergency in January, it triggered rules requiring any tests to pass the FDA’s “emergency use approval” process, raising the bar for tests developed and run inside a single laboratory. 5/

The effect was that the nation’s labs could only run tests using CDC’s kits. They couldn’t order their own primers and probes, even if they were identical to the CDC's.

Then a big problem happened: the CDC’s kits turned out to be flawed. And there was no plan B. 6/

Incredibly, the US didn’t switch to a test developed for the World Health Organization that's currently in use in more than 120 countries. It may have been bureaucracy—getting the test approved for use in the US may have taken too long. Some suspect it may be politics. 7/

On February 29, facing mounting pressure to expand testing capacity, the FDA changed its regulations to allow certified clinical labs to develop and begin using their own tests to detect #COVID19 without prior approval. 8/

Under the new policy, FDA review will still be required, but labs will have two weeks to send data to the FDA after internally validating the tests. In the meantime, they can start using their diagnostics to test patient samples. 9/

But where regulatory barriers have been removed, logistical ones have arisen. 10/

If scientists want to detect a virus like SARS-CoV-2, they first have to turn its genome, which is made of single-stranded RNA, into DNA. The CDC’s protocol recommends an RNA extraction kit sold by Qiagen. But ... those kits are now on backorder. 11/

So what does all this all mean for you? Whether or not you can get tested for Covid-19 will depend largely on where you live and how quickly health workers in your area can be supplied with test kits. 12/

So in the meantime, practice social distancing. Avoid large gatherings and wash your hands. Help your elderly neighbor stock up on supplies. Anything you can do for the most vulnerable is going to be part of the real fight against the disease. 13/ wired.trib.al/FNGJOfk