Since July, the administration had been rushing out the machines from manufacturers Becton, Dickinson and Company and Quidel to more than 14,000 facilities around the country in an attempt to identify outbreaks faster and stem the tide of the virus, which has taken a particular toll on the elderly, especially those in nursing homes and other assisted living facilities.
“We have a real crisis around testing,” said Dr. Michael Osterholm, an epidemiologist and director of the Center for Infectious Disease Research and Policy at the University of Minnesota. “We don’t have the capacity to supply every facility with … the more reliable and accurate tests and the tests we do have are not accurate and unreliable.”
The machines process cheaper-to-produce kits known as antigen tests — which can yield results in 15 minutes. While other diagnostic tests for COVID-19 like PCR tests look for genetic material from the virus, antigen tests look for molecules on the surface of the virus, diagnosing an active coronavirus infection faster than molecular tests.
Although they are not perfect, many experts view these tests as an important component in the effort to fight COVID-19. The rapid turnaround time means they can be used in bulk to screen dozens of people in quick succession, with any potentially positive cases later confirmed with a more accurate PCR test. These are the tests, for instance, that the White House requires everyone to take before they enter the complex.
“Antigen tests may be a better screening tool than a diagnostic tool,” said Dr. Mark Abdelmalek, an ABC News medical contributor. “It is a helpful way to screen many at risk people, especially if done frequently. Antigen tests may not be the best at telling you who has COVID, but they can be very helpful for telling you who is likely to transmit COVID.”
Abdelmalek added that while antigen tests may not be as sensitive as molecular tests, they play a role in controlling the pandemic because of their ease, speed and potentially lower cost. The idea behind sending them to nursing homes, he said, was so rapid tests could serve as an early warning system, even though they might not find every case.
High rates of false positives in some cases
Some states are reporting that these tests, which have produced a rate of false negative results as high as 50%, according to an article published by the American Association for the Advancement of Science, are now also yielding false positives, an outcome of deeper concern to state health officials.
This was the case last week in Nevada, where health officials announced they would discontinue the use of antigen tests provided by the Centers for Medicare & Medicaid Services after state data reported that 60% of a sample from 60 positive antigen tests from 12 facilities of positives were false.
Days after announcing the halt, Nevada health officials grudgingly reversed course under pressure from the federal government, directing nursing homes to restart their use of the rapid coronavirus tests on Friday.
“We are very disappointed by the letter received today from the [Adm. Brett] Girior,” the federal health official who oversaw the distribution of testing equipment to nursing homes, said Dr. Ihsan Azzam, Nevada’s chief medical officer in a statement to health care providers.
“If this laboratory data discrepancy had been reported to Dr. Girior, we would hope he would have taken the same action as Nevada to protect our vulnerable population and ensure no further harm occurred while we further conducted our investigation,” Azzam said. “We too want more testing with rapid turnaround in Nevada, but the results of those tests must be accurate as they affect clinical care.”
On a call with reporters on Friday, Giroir said that all tests will have false positives.
“These are expected and appropriate, especially for screening tests when used in populations with a low prevalence of infection,” Giroir told reporters. “Bottom line, the recommendations in the Nevada letter are unjustified and not scientifically valid.”
Others sound the alarm
Nevada has not been alone in sounding alarms about the federal testing kits. Several states told ABC News they are also reevaluating the antigen testing equipment, with many of them saying they are providing nursing facilities with more accurate molecular tests, known as PCR (polymerase chain reaction) tests, that can take two to three days to process, assuming no backlog.
According to the FDA, PCR tests were designed to minimize false positives.
Andrea Wojcik, a spokesperson for the Office of Health and Risk Communication in Delaware told ABC News that results from antigen tests showed a “concerning percentage of false positives. He said the state is following recommendations from the Centers for Disease Control and Prevention (CDC) to make sure any positive test result using antigen testing in a long-term care facility will be supplemented with a follow-up PCR test and sent for priority processing at the state laboratory.
A spokesperson for the health department in Pennsylvania said they too have experienced “a small subset of tests where false positivity was a concern in our long-term care facilities.” And in Oregon, the department of health says it is re-evaluating testing guidance regarding the antigen testing kits “given the reports of false positive results nationally and planning internal validation studies.”
”We are also investigating any reports of false positive results in Oregon,” said Dr. Melissa Sutton, the medical director of respiratory viral pathogens at the Oregon Health Authority.
Other states are also relying on their own system using the more accurate PCR tests to screen nursing homes for the virus. Av Harris, a spokesperson for the Connecticut Department of Public Health told ABC News the state is only using PCR tests in long-term care facilities. The state began testing nursing homes with the PCR tests before the antigen tests were sent to states by the federal government.
“Since June, Connecticut set up a state-funded comprehensive nursing home testing program for residents and staff that uses PCR tests with locally based labs who can guarantee timely processing of samples for quicker results with no backlog,” Harris said.
State officials from Arkansas, New Jersey Wisconsin and Minnesota told ABC News they are also primarily using routine PCR tests in long-term care facilities.
“This approach avoids many of the challenges associated with antigen testing,” said Elizabeth Goodsitt, a spokesperson for the Wisconsin Department of Health Services.
Doug Schultz, a spokesperson for the Minnesota Department of Health said that “if a long term facility is able to meet their testing needs with PCR testing, that is generally recommended.”
Five states including California and Arizona told ABC News that they do not have reports of widespread problems with false results from antigen testing machines.
False positives were a surprise
When the Food and Drug Administration (FDA) authorized the rapid testing equipment from BD and Quidel, it acknowledged there was a higher chance of false negatives but did not mention false positives.
But in July, the FDA sent a letter to health care providers, alerting them of an increased risk of false positive results from the BD testing kits. The agency recommended confirming the initial result with an alternate type of authorized test.
“The FDA is aware of reports of false positive antigen tests in nursing homes,” said a spokesperson for the FDA on Tuesday. “We will continue to monitor and evaluate these reports and other available information about device safety and performance.”
The letter noted that in one study, the manufacturer found approximately 3% of results were false positive results. BD, the trade name of the New Jersey-based medical supplier Becton, Dickinson and Company, has said they have “full confidence” in their testing equipment.
“We believe the test is performing as intended in Nevada – rapidly detecting true positives to help reduce the risk of an outbreak among some of the nation’s most vulnerable individuals,” said Kristen Cardillo, BD’s vice president of global communication.
A spokesperson for Quidel told ABC News in a statement that “complaints of discordance are extremely rare.” “
“We activate Quidel’s rigorous Quality Control Management System and conduct a thorough analysis to determine the root cause of the alleged discordance,” the statement stated. “Once our investigation is complete, we address any issues identified — such as inadequate training and improper handling. We have yet to see a problem with the test product to date.”
The false positives from antigen tests have raised concerns among health experts, who worry nursing homes will see an increase in infected residents.
“A positive test triggers action in these facilities,” said Emily Gurley, an epidemiologist and contact tracing expert at the Johns Hopkins Bloomberg School of Public Health. “The staff member must isolate and quarantine all of their contacts. If the person is truly positive, these are prudent steps. If the test was a false positive, these actions are unnecessary disruptions and burdens.”
Similarly, Geoffrey Baird, the acting laboratory-medicine chair at the University of Washington told ABC News that many facilities use testing to “co-locate” infected patients.
“If you mistakenly identify a non-infected person as infected, you would put a non-infected person in contact with infected people, potentially infecting them or worse,” Baird said.
“Long-term care facilities need to know if residents have COVID-19 or not and these tests are just too unreliable,” said Dr. Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota. “If you can’t trust the results, it’s a real challenge.”