One of the country's largest clinical laboratory operators, Quest Diagnostics (NYSE: DGX) says that by mid-May, it will have enough capacity in the U.S. to perform over 200,000 COVID-19 antibody tests per day. Management made that forecast during Wednesday's  otherwise depressing first-quarter earnings call. 

On Tuesday, Quest Diagnostics began performing tests for the antibodies produced by immune systems that are fighting off SARS-CoV-2, the coronavirus responsible for COVID-19. There's nothing necessarily wrong with antibody tests, but they aren't much use when it comes to a virus containment effort, nor for immediate diagnostic purposes. People don't usually develop the antibodies that Quest is testing for until 14 days after they have started to show symptoms. They can, however, help shed light on how widely the coronavirus has spread, and whether those who have recovered from COVID-19 have some degree of protection from reinfection.

Lab tech loading a rack of sample tubes.

Image source: Getty Images.

There's a good chance Quest Diagnostics can double the capacity for coronavirus testing in the U.S. within a few short weeks. The number of tests performed daily peaked on April 4 at 229,268. During the week ended April 21, the COVID Tracking Project recorded an average daily volume of just 153,365 tests.

Not there yet

Public health officials around the world agree that adequate testing is a prerequisite to governments being able to safely relax stay-at-home orders. Epidemiologists generally say they want to see less than 2% of COVID-19 tests coming back positive -- results at that level would suggest that everybody who should be getting tested is getting tested. If the rate of positive results is more than 10%, it's an indication that access to testing is too limited for the country to avoid another surge of outbreaks.

During the past week, around 18% of U.S. COVID-19 tests performed came back positive. Efforts by Quest and its peers will go a long way to help lower that percentage, but it's going to be a while before we can hang out again without risking each other's lives.

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