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WATCH: Your questions about COVID-19 testing, answered

As states across the country wrestle with how to reopen after closures brought on by the coronavirus, testing will be a key part of monitoring the spread of COVID-19. But a number of questions remain about how many tests are available, and to whom, along with the differences between testing for the virus and testing for antibodies.

Watch the live Q&A in the liveplayer above.

Dr. Joshua Sharfstein, vice dean at Johns Hopkins University’s Bloomberg School of Public Health and former deputy commissioner for the Food and Drug Administration, and the PBS NewsHour’s William Brangham answered a few questions from viewers on COVID-19 testing.

How accurate are the current tests?

As testing for COVID-19 becomes more available, many are wondering if the tests can accurately and efficiently detect the virus. Sharfstein said the situation is complicated.

Right now, tests have the best success detecting the virus five to six days after infection and after symptoms have begun to show. That’s because the virus has grown enough within the body to be easily discovered in a test sample, either from saliva or blood.

Before that time, there’s a higher chance the test will come back with a false negative.

“You could test negative even if you have it,” he said.

In many cases, people want to get tested immediately after potential exposure, but Sharfstein said a test that early will likely yield inaccurate results.

All tests, however, are not assuredly accurate, even after the post-symptom period, which is why Sharfstein recommends everyone should adhere to the two week self-quarantine period if there’s a chance, or suspicion, that they’re infected.

What’s the cause of the U.S. testing shortage?

The U.S. is behind in testing because of a failure in the CDC’s early efforts, according to Sharfstein.

“We were late in getting started on testing,” he said.

He explained the CDC’s initial effort to create a testing method failed because of contamination within their labs, which meant more time was needed to create a working testing method and distribute it among health care providers. Once distributed, public health workers needed to set up the tests to ensure they produced valid results.

Alongside this failure, Sharfstein said there’s a shortage of supplies needed to actually perform the different tests.

“We’re probably, by different estimates, maybe about half or even a third, of where we would like to be,” he said.

That said, Sharfstein also emphasized that tests are just one part of curbing the pandemic. While testing is vital, learning how the virus spreads and ways to limit exposure will be key to minimizing the pandemic. Contact tracing and isolating people with known or possible exposure are also critical to boxing in the virus.

“Testing alone is not disease control,” he said.

Who can get tested?

Early in the pandemic, it was reported that NBA players were getting tested for the virus, despite not having any symptoms. At the same time, Americans in some areas of the country said they could not get a test, causing many to question whether testing was being distributed equitably across economic and racial lines.

“We built this testing system on top of a health care system that has all these different biases built in to it,” Sharfstein said.

READ MORE: Exclusive: Warren, Pressley and other lawmakers demand answers from White House on COVID-19 racial disparities

Existing unequal distributions, such as who can pay for insurance and who has physical access to medical care, may affect where testing and virus care will go.

Sharfstein noted that local officials are in the process of alleviating these disparities using mobile testing centers and community testing sites.

READ MORE: ‘The worst is yet to come.’ How COVID-19 could wipe out many rural hospitals

He also noted that Congress has set aside money to ensure that anyone looking to take a test will not be charged, regardless of whether they have insurance. However, Sharfstein said that if you don’t get tested during a visit, you may still be charged for the appointment.

While it would be ideal to have a consistent place to simply walk in and receive a virus test, “that isn’t a reality in the United States.”

When should you seek out a test?

For many Americans, the essential question is when they should actually get tested for COVID-19. Sharfstein laid out multiple scenarios.

If you are experiencing known coronavirus symptoms — including shortness of breath, fever and headaches, you should seek medical care and get tested as soon as possible.

“People who are struggling to breath even a little bit should be seen” by a doctor, he said.

While testing has gradually become more accurate and available in the U.S., many may still experience symptoms, even after they’ve tested negative. That’s why Sharfstein again emphasized the importance of self-quarantine while waiting for a result, or even after the test comes back negative.

“Even if it’s not COVID-19, staying away from others will protect them from infection,” he said.

A consistent anxiety surrounding the coronavirus pandemic is what to do if you think you’re asymptomatic, especially after potential exposure to someone you know who has tested positive.

“The truth is, it’s very hard to know, if you have no symptoms,” he said.

At that point, the best course of action is still to self-quarantine, especially since tests aren’t dependable before symptoms appear. It’s also important, if possible, to stay in touch with your doctor about your symptoms.