Forty percent of U.S. Covid-19 tests come back too late to be clinically meaningful, data show

Published by CNBC.COM

Summary generated on August 16, 2020

    The results still hadn't been returned.

    She was tested July 1, and her results didn't come back until July 24.

    Health experts say two days or less is optimal for returning Covid-19 test results to make them useful for stopping transmission.

    If test results take more than three days, people are unlikely to self-quarantine and getting in touch with the people they interact with during that time - potentially spreading virus - can be difficult.

    "It's really clear that if tests take more than 48 hours, you've lost the window for contact tracing," Dr. Ashish Jha, professor of global health at Harvard University, said in an interview.

    "I think, basically, beyond 72 hours, the test is close to useless."

    A survey run by CNBC in partnership with Dynata, a global data and survey firm, suggests almost 40% of Americans had to wait more than three days for their results, rendering them - by Jha's definition - useless.

    Others, like Arizona and West Virginia, were closer to four and a half days, on average.

    Indiana's average test turnaround time was more than five days.

    Jha said the variation is evidence of a fragmented testing strategy in the U.S. "It would take a national testing strategy to make sure that, if there's excess capacity in Massachusetts, but long lines in Florida, that Massachusetts could help Florida out," Jha said.

    "Largely we have not had a national testing strategy. The strategy out of the White House has been for every state to figure this out on their own."

    Admiral Brett Giroir, the Trump administration's Covid-19 testing czar, told NBC's Andrea Mitchell this week that results that take seven to 14 days are outliers.

    "In general, if you do need a test - you fall in the categories of needing a test, even for public health tracing - you're going to get that result within 48 to 36 hours," he said.

    Not everyone needs tests, Giroir said, and the national testing approach is "Strategic testing, not shotgun testing," which he said has reversed the outbreaks in that region.

    Testing in both states is also down, by 42% in Florida and 41% in Arizona.

    The net result in Florida is that the positivity rate - the percentage of all tests that turn out to be positive - has remained around 18% since early July.

    In Texas, testing is down by half, prompting questions about whether cases are truly declining as much as the numbers would indicate, or if the decreased testing is obscuring the true picture.

    Overall, the Dynata data show that testing turnaround times have declined in the U.S. since March, from more than four days, on average, to now just less than three and a half.

    "The fact that six, seven months into a pandemic, we can't do a simple diagnostic test is unbelievable," he said.

    "The rest of the world is mostly looking at us with a state of disbelief that America can't run simple lab tests on an infectious disease that we've known about for seven months."