Mention Covid-19 testing and it’s hard not to revisit the debate over rapid versus PCR tests or conjure images of long lines of people waiting for nasal swabs as demand outpaced supplies. Early days of testing focused on the short-term need to make a definitive diagnosis prior to the ramping up of vaccine production and distribution to subjugate the spread.
Testing has come a long way since those early days. Saliva and other less invasive methods are now available for widescale use at home and the office without medical supervision or prescription. Good accurate testing continues to be used as it is needed to allow the public to engage with their families, workplaces and community with confidence and for state and national leaders to understand whether vaccinations are effective and if the new mutant variants are continuing to spread.
Health experts around the globe suggest that we need to switch the purpose of testing from purely diagnostic to helping us mitigate spread and get back to “normal.” One of the best ways to do this is to make the tests easy to do at home or work without sacrificing accuracy.
We agree with epidemiologists at the Johns Hopkins Coronavirus Resource Center Dr. Jennifer Nuzzo and Emily Pond’s recent New York Times opinion piece, “As more contagious coronavirus variants emerge and lockdown measures are relaxed, the nation needs to intensify, not scale back, nationwide testing efforts.”
Unfortunately, the U.S. is moving in the wrong direction on testing. According to new research from Johns Hopkins Coronavirus Resource Center, the number of daily tests has declined 35 percent since mid-January.
Our safe return to work, school and travel requires a long-term and consistent testing protocol. On March 17, Centers for Disease Control updates for colleges, school leaders and employers suggested that they develop approaches that include regular and bulk testing of students and workers and periodic testing at regular intervals.
An April 3 flight from New Delhi to Hong Kong is an example of how we’re only as safe as the most careless testing, tracing and quarantine protocols allow. After all passengers were required to provide proof of negative tests, four passengers tested positive on arrival and within two weeks a third of the passengers tested positive. While it is possible that some passengers on the plane got infected in the country after their preflight virus test, this cluster reinforces the need for reliable and accurate tests. This also underscores how easy it is to transmit the virus on airplanes – and the workplace is no different.
At the peak, more than 300 COVID-19 tests and sample collection devices were authorized by FDA under emergency use authorizations. Today over 200 COVID-19 tests are on FDA’s removal lists while other tests remain on the market but have been flagged by FDA for potential inaccurate results. This is happening because the majority of tests target the E-gene, ORF1a, Orf 1b and RdRP parts of the viral RNA. These viral sequences are rapidly mutating. Tests that target this region fail and generate what are called “false negatives.” The virus is present but is not being detected by the test. This could be as high as 25 percent according to our preliminary research.
Of more concern is the current focus on rapid tests and antigen or antibody tests as the primary approach and the false sense of security people derive from them. These tests have low sensitivities for detecting the virus especially at low viral loads. Accuracy rates below 50% are common. Such tests are being used more often because people perceive that they are cheaper and easier to use. Frankly, the ability for these tests to detect the virus is no better than a coin toss since the accurate detection of those who are virus-free is artificially inflated. It is inarguable that a negative test has limited to no value. The CDC even recommends confirming negative results using a gold-standard PCR test which means companies would need to do double the amount of testing! Sticking with a PRC test right away is the way to go for accuracy and cost-effectiveness.
For all of the challenges at play, there are some areas of progress where we can direct our efforts and ensure long-term results. Here are a few we’ve identified:
- Normalizing of frequent, accurate (gold standard PCR) testing in businesses, schools and communities will suppress the localized spread of new variants and allow “normal” to return faster and with confidence.
- Know the test validity and demand fast, accurate and reliable tests and results.
- Broader testing will naturally pricing as economies of scale come into play.
Rapid, cheap approaches to testing are largely unreliable. The long-term approach to COVID-19 testing is ready now – and the sooner we roll out accurate solutions, the better for all.
Mark Kidd is the scientific and laboratory director of Wren Laboratories, a genomics biotech company in Branford.