Washington After struggling to ramp up coronavirus testing, the United States can now screen several million people every day, thanks to a growing supply of rapid tests. But prosperity comes with a new challenge: keeping track of results.
All U.S. test sites are required by law to report their results, both positive and negative, to public health agencies. But state health officials say many rapid tests go unreported, which means some new cases of COVID-19 may not be counted.
Experts say the situation could get worse. The federal government is shipping more than 100 million of the latest rapid tests to states for use in public schools, assisted living centers, and other new testing sites.
“Certainly, schools do not have the capacity to report these tests,” said Dr. Geoffrey Engel of the State Council and regional epidemiologists. “If it does at all, it is probably too paperless, very slow, and patchy.”
Early in the outbreak, nearly all US testing relied on genetic testing that could only be developed in high-tech laboratories. Even in the best of circumstances, people had to wait two to three days for results. Experts have pushed for more rapid “point-of-care” tests that can be performed in doctors’ offices, clinics and other locations to quickly find infected people, place them in quarantine and stop the spread of the disease.
Starting in the summer, cheaper, 15-minute tests – which detect the presence of viral proteins called antigens on the nasal swab – are available. Early versions still need to be addressed with portable readers. The millions of new tests from Abbott Laboratories now coming out to the states are easier to use: they are the size of a credit card and can be developed with a few drops of a chemical solution.
Federal health officials say about half of the nation’s daily testing capacity now consists of rapid tests.
Hospitals and large laboratories provide their results electronically to state health departments, but there is no standardized way to report the rapid tests that are often performed elsewhere. State officials were often unable to track where these tests were shipped and whether results were being reported.
In Minnesota, officials set up a special team to try to get more test data from nursing homes, schools, and other newer testing sites, to be inundated with faxes and paper files.
“It’s definitely a challenge because we now have to do many more things manually than we used to do ER reporting,” said Christine Eresman, of the Minnesota Department of Health.
Even before Abbott’s latest quick test hit the market last month, the downgrade was a concern.
Competitors Quidel and Becton Dickinson have shipped more than 35 million rapid tests since June. But this massive influx of testing did not show up in the national test numbers, which often ranged from 750,000 to 950,000 tests per day for several months.
Besides counting new cases, COVID-19 test numbers are used to compute a key metric when an outbreak occurs: the percentage of people who test positive for COVID-19. The World Health Organization recommends countries test enough people to push their positivity below 5%. The United States has been hovering mostly around or below this rate since mid-September, a point that President Donald Trump and his top aides have promoted to say the nation has crossed the corner when the outbreak occurs. The number has decreased from a peak of 22% in April.
But some disease-tracking professionals are skeptical. Engel said his group members believed they weren’t getting all the results.
He said, “So it may be a wrong result.”
One of the challenges facing accurate counting: Countries have vastly different approaches. Some states bundle all kinds of tests together in one report, others don’t schedule rapid antigen tests at all and some don’t publicize their system. Because antigen tests are more prone to false negatives and sometimes require retesting, most health experts say they should be recorded and analyzed separately. Currently, only 10 countries are doing this and publishing results online, according to the COVID Tracking Project.
The federal government assigns tests to states based on their population, rather than helping them develop a strategy based on the size and severity of their outbreak.
“That’s just lazy,” said Dr. Michael Mina of Harvard University. “Most countries will not have the expertise to know how to use it appropriately.”
Instead, Mina said the federal government should direct limited supplies to major hotspots across the country, reducing infections in the hardest hit communities. Maintaining tighter control will also ensure that test results are reported quickly.
Johns Hopkins University researcher Gigi Grunvale agrees that health officials need to think carefully about where and when the tests will be published. Ultimately, test-tracking methods will catch up.
“I think having the tools to determine if someone is contagious is a higher priority,” she said.
Associated Press data journalist Nikki Forster contributed to this story
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