Here’s what’s happening with rapid COVID-19 tests

There are three types of COVID-19 testing:

• Genetic (or molecular) tests are the most accurate and include the reverse transcription polymerase chain reaction (RT-PCR) test to identify ribonucleic acid (RNA) from saliva or a nasal swab.
• Antigen tests find specific proteins on the surface of the virus.
• Antibody tests can determine if the person had the virus, but they will not detect an active infection.

Rapid RT-PCR tests

Because the SARS-CoV-2 genome is made of RNA, you must convert it to DNA and then run a polymerase chain reaction on it.

The polymerase chain reaction (PCR) is a technique that amplifies DNA.

The enzyme that converts the genome from RNA to DNA is called “reverse transcriptase” or RT.

To test for the virus, you need to perform reverse transcriptase and then PCR, also known as an RT-PCR test, explains Dr. Geoffrey Baird, Acting President of Laboratory Medicine at the University of Washington School of Medicine. Sometimes people shorten the name of the technique to PCR, he told Healthline.

Rapid tests, also known as site-of-care tests, don’t require a lab and can be done anywhere, including at home.

Rapid molecular tests or RT-PCRs include ID NOW from Abbott, cobas from Roche, Cue COVID-19 Test from Cue Health, Xpert Xpress from Cepheid and Accula from Mesa Biotech.

“Currently, there are four rapid antigen tests and five rapid molecular tests. currently on the US market. that are approved by the Food and Drug Administration (FDA) under the Emergency Use Authorization (USA), ”said Dr. Amy Karger, medical director of the West Bank Laboratory at MHealth Fairview.

Rapid antigen tests

Rapid antigen tests look for signs that a person has antibodies to SARS-CoV-2.

These tests are much less sensitive (and accurate) than an RT-PCR test, Baird says.

These antigen tests do not indicate whether a person is in the midst of an active infection, but simply whether they had the disease in the past to the point of developing antibodies to the disease.

Quidel’s Sofia, BD’s Veritor, Abbott’s BinaxNow, and LumiraDx are rapid antigen tests.

Increasingly, medical experts are working to create rapid and accurate tests for COVID-19 that people can perform before traveling or to avoid a quarantine upon reaching a new state.

A 90-minute COVID-19 test known as CovidNudge produced by DnaNudge, a startup from Imperial College London, is already in use.

A study on the nasal swab test in The Lancet Microbe found that the RT-PCR test has a sensitivity of more than 94 percent and a specificity of 100 percent. Therefore, it was accurate, produced no false positives, and produced few false negatives.

While Baird finds the CovidNudge test interesting, he says it’s not a breakthrough. It is easy to make a PCR device and there are many on the market.

“Until they can produce millions of these cartridges a week and bring them to large-scale end users at a very low price (which no supplier in the world has ever been able to do), it alone will not solve our problems. global, ”Baird said.

Amira Roess, PhD, MPH, a professor at George Mason University in Virginia, says the CovidNudge test sounded promising. More work will be needed to see if the high sensitivity and specificity are maintained once the test is used more widely.

Recently, University of Illinois researcher Dr. Martin Burke created I-COVID, a rapid saliva-based RT-PCR test that received emergency use clearance from the FDA.

The FDA also issued an emergency use authorization for the BinaxNOW COVID-19 Ag card. It is a rapid antigen test, so it is not as accurate as an RT-PCR test.

Several tests on the horizon have received funding through the National Institutes of Health (NIH) Rapid Acceleration of Diagnostics (RADx) Program. The program aims to accelerate innovations in COVID-19 testing.

RADx presented an award to Mesa Biotech for a portable RT-PCR test that uses a single-use cartridge and can produce results in 30 minutes. Another award went to Quidel Corporation for a 15 minute test that is specified for nursing homes.

Karger says MicroGEM InternationalThe proposal for a home testing device could “significantly expand access to tests if they can be sold in pharmacies in a manner similar to over-the-counter pregnancy tests.”

Some experts argue that frequent and highly accessible testing could delay the pandemic.

But it’s unclear whether consumers would widely adopt at-home testing because they would likely have to pay out-of-pocket for the tests, Karger notes.

“We also don’t know yet whether this test will meet FDA precision standards,” Karger said of the MicroGEM test. “It is also unclear whether the company can avoid supply chain problems that have affected other manufacturers, which could impede widespread distribution and availability of testing to consumers.”

Clinical trials are currently underway with ICHORtec, a rapid test system that can detect active SARS-CoV-2 infection and antibodies in non-laboratory settings in 3 minutes.

Meanwhile, an XPRIZE contest promises to turn over millions to a winner who develops an exceptional rapid COVID-19 test.

Roess believes we will see more tests developed that use saliva and other easily collected samples.

“Several companies are trying to find ways to allow patients to collect the samples themselves, thereby minimizing the burden on the healthcare system, as well as the risk of transmission to healthcare workers who collect samples,” said Roess.

On September 22, TCA / GENETWORx Labs announced their new saliva RT-PCR test, which promises results within 48 hours of testing. It is not the first saliva test, as there are some others available.

In August, the FDA granted an emergency use authorization for the SalivaDirect test from Yale University. SalivaDirect is not a home test and must be performed in a laboratory.

Karger is excited about the new fast and inexpensive tests, but cautioned the public that the tests are generally less accurate. Most of the evidence for the efficacy of antigen testing was demonstrated under ideal conditions. Accuracy may decrease when testing is performed by non-professionals outside of a clinical setting.

That’s why we must consider that implementing largely inaccurate testing could erode public health authorities, science and medicine, Karger says.

While a lot of attention has been paid to a possible COVID-19 vaccine, getting accurate and rapid tests is key to controlling the outbreak.

Even if a COVID-19 vaccine is approved in the next few weeks, and that’s not guaranteed, it will be months before most Americans have access to that vaccine. As a result, there will still be a role for testing in the future, but the extent of that testing demand is difficult to predict, Baird explained.

Stephen Kissler, PhD, a postdoctoral fellow at Harvard’s TH Chan School of Public Health, told Healthline that the vaccine will provide one more tool to prevent the spread of the virus, but will not end the pandemic.

“To manage the spread, we will still need to use all the interventions that we have available, and rapid tests will be a key part of this,” he said. “We still need greater availability of rapid tests, but this is something that could feasibly happen in the coming months.”

As for what rapid testing will improve, Baird believes it all comes down to preventive measures and a vaccine, both of which will reduce the need for testing.

“There is no panacea on the horizon, which means a test that is simultaneously nearly free, incredibly fast, and perfectly accurate,” continued Baird.

“Testing is all we can really do now to mitigate the effect of the virus, but we cannot test our way out of this pandemic. The virus spreads due to human behavior, and changing human behavior is the only way out of it. “

Supply chain issues have become the biggest barrier to increasing test volumes, Karger adds.

“In theory, we now have many test options available, but the problem is that there are not enough reagents or materials for labs to run these methods at full capacity.”

The development of new tests, especially those that do not rely on routine laboratory supplies, is of interest, as are “multiplex” tests that can detect more than one virus, such as SARS-CoV-2, RSV, streptococci and flu at the same time, Karger added.