It will take something on the order of 200 million COVID-19 screening tests per month, as opposed to the 25 million being performed currently, to safely reopen the U.S., estimates a new report
from Duke University. Because of their low costs, scalability and speed, antigen tests may play a crucial role in meeting this unprecedented level of demand, particularly in nursing home, educational and workplace settings. However, if antigen testing is to be the answer, there is one significant problem that will need to be addressed: lack of reliable and consistent test data reporting.
The Promise of Antigen Testing
What the country and world need right now are point-of-care tests that can deliver accurate results at cost-effective prices that can be utilized to screen asymptomatic populations. Molecular tests using reverse transcription-polymerase chain reaction (RT PCR) to detect RNA material from the SARS-CoV-2 virus performed at an offsite laboratory are accurate but too slow and expensive to satisfy the need for screening services. Blood-based serology tests that detect SARS-CoV-2 antibodies are better suited for widespread and rapid screening, but lack the specificity and sensitivity of RT PCR assays.
Antigen tests that detect viruses indirectly by identifying the presence of antigens or toxins a virus produces that cause the body to produce antibodies are relatively inexpensive to produce and generate results rapidly at the point of care. And while its relative lack of sensitivity creates the risk of false negatives and need for confirmatory testing, antigen testing may still be appropriate for applications like screening health care workers and other high-risk groups and triaging patients during peak outbreak periods.
Moreover, developers and manufacturers of rapid antigen tests have declared that they are ready and able to meet demand for increased testing in the coming months. On Aug. 26, the U.S. Food and Drug Administration (FDA) announced that it had granted Emergency Use Authorization to Abbott Laboratories’ BinaxNow COVID-19 Ag Card, a SARS-CoV-2 antigen test that does not require an analyzer to read the results. The $5 test provides results in 15 minutes from a nasal swab that is twirled on a test card with a testing reagent added. The results can be read directly from the card, like a pregnancy test, with one line indicating a negative result and two lines indicating a positive result. Other heavyweights like Roche, Quidel and LumiraDx have or soon plan to launch rapid and scalable SARS-CoV antigen tests that can be delivered on a bulk basis.
The Potential Stumbling Block
The cloud to the antigen testing silver lining is the lack of an adequate data reporting infrastructure to support it. The same features that make antigen testing so scalable also complicate reporting of test data to public health authorities. By contrast, testing laboratories have the equipment, skills and experience to report data electronically. Accordingly, more than 20 states either do not release or have incomplete data on rapid antigen testing, according to a new report
from Kaiser Health News (KHN). After surveying the states on how they collect and report antigen test results, KHN found that:
- 21 states and the District of Columbia do not report all antigen test results;
- 15 states and D.C. do not count positive results from antigen tests as COVID cases;
- Two states do not require antigen test providers to report results;
- Five states require only positive results to be reported; and
- Nearly half of states believe their antigen test results are underreported.
This resulting lack of data bedevils the efforts of public health officials and policy makers charged with monitoring the scope of the pandemic and making crucial decisions about reopening schools and other forms of public activity. It also artificially deflates the number of COVID-19 cases, potentially creating the dangerously false impression that the infection rate is declining when the virus is actually spreading on a continued or even accelerated rate. And as utilization of antigen testing continues to expand, this blind spot will only continue to grow.
States that Don’t Report Antigen Test Results or Don’t Count Antigen Positives as COVID-19 Cases
California, Colorado, District of Columbia, Georgia, Illinois, Maryland, Minnesota, Missouri, Montana, New Hampshire, New Jersey, North Carolina, North Dakota, Ohio, Pennsylvania, South Dakota, Tennessee, Texas, Vermont, Virginia, Washington, Wisconsin, Wyoming
: Kaiser Health News
What Counts as a COVID-19 Case
Part of the problems with antigen test reporting is that under U.S. Centers for Disease Control and Prevention (CDC) guidance, a case must be determined from a RT PCR test to be considered a “confirmed” case of COVID-19. Positive antigen tests are considered “probable” COVID-19 cases because the tests are less accurate. In early August, the CDC revised its guidelines to allow a positive antigen test to count as a probable case without assessing whether the person has COVID-19 symptoms or close contact with a person confirmed as having the virus.
This asterisk placed by the CDC on antigen positives has led to a disconnect among state reporting rules, with some states requiring reporting of only “confirmed” COVID-19 cases while others require reporting of both “confirmed” and “probable” cases.
Reporting of test data will be crucial to contain the spread of COVID-19 and make scientifically sound decisions about the pace and scope of reopening. In recognition of this, the U.S. Centers for Medicare Services recently imposed draconian new testing requirements on skilled nursing facilities and stepped up the penalties for violations of existing reporting rules for hospital and other laboratories. As the use of rapid antigen testing proliferates, policy makers at both the federal and state levels will have to confront and resolve the problems that are currently preventing full, consistent, and accurate reporting of antigen test results.