Rapid Antigen Tests: Why The Hype & How To Use Them?
By: Cheryl Herbert
Tags: Covid 19 Testing, Covid 19

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By Cheryl Herbert & Kyle Tretina, Ph.D

A recent study by the University of Colorado Boulder and Harvard University reinforces what many epidemiologists say is the need for more widely spread use and increased supply of rapid antigen tests to combat spread of COVID-19. The study shows that test sensitivity — the major attribute of an RT-PCR test, is secondary to frequency and turnaround time — features associated with rapid antigen tests.

RT-PCR and antigen tests are both diagnostic tests that can be used to identify an active COVID-19 infection. However, each has fundamental and distinctive differences, including pros and cons on how, why and when it’s best to use them as part of a preventative testing program.

To help you navigate the waters of RT-PCR vs. rapid antigen testing, Meenta’s scientific expert, Kyle Tretina, Ph.D., answers questions on the deservedly “hyped” rapid antigen test and its role in preventing outbreaks of COVID-19.

First and foremost, why are RT-PCR tests called the “gold standard”?

RT-PCR stands for Reverse Transcription Polymerase Chain Reaction and is the basis of a molecular test that detects genetic material — the RNA of the coronavirus. RT-PCR tests are highly sensitive, which enables them to detect the smallest traces of the virus (viral RNA) even prior to the infectious stage, and including asymptomatic patients. What also makes this test so highly touted is its low-level of false negatives. For these reasons, RT-PCR is considered the “gold standard” for detecting COVID-19.

RT-PCR has “gold medal” status as the best test to diagnose COVID-19

2. What’s the difference between RT-PCR and antigen tests?

Whereas RT-PCR tests look for genetic material of the virus, antigen tests detect certain protein molecules from the surface of the virus. Antigen tests do not have the same level of extreme sensitivity as RT-PCR. They are optimal in detecting infection when virus levels in the body are high or at peak contagious levels (typically 5–14 days after infection onset). With that said, antigen tests can detect COVID-19 quickly (10–30 min depending on the test) and are an important testing weapon to help prevent COVID-19 outbreaks.

3. How are RT-PCR tests best used?

RT-PCR tests are historically used as a diagnostic test in a clinical setting to detect disease and monitor its progression. They’re also used to diagnose genetic diseases: cancer detection and other diagnostic uses.

They’re the mainstay for confirming a COVID-19 diagnosis and play an integral role in any COVID-19 testing program — either as the primary diagnostic testing method or part of a screening or surveillance testing program. When paired with screening or surveillance testing, RT-PCR tests are often used as the follow up confirmatory diagnostic test on any positive result from other testing methods like rapid antigen or pool testing.

4. What are the downsides of using RT-PCR tests?

The drawbacks of using RT-PCR as your primary testing method are — time and money:

They’re expensive, costing around $85-$150 on average, per test. This gets costly fast if you plan to test regularly and depending on the number of people you expect to test.

Require the use of a lab to process.

Results take a few days, or longer.

Note: Meenta’s COVID-19 testing marketplace guarantees results in 24–48 hours, which is important when RT-PCR is used as part of any testing program.

5. What are the benefits of rapid antigen tests? (See Table 1 above)

Rapid antigen tests do not require a lab to process. They use what’s called, lateral flow technology. A home pregnancy test is the most visible example of this type of technology.

Results are available in 10–30 minutes which helps organizations make informed decisions more quickly and thus can prevent outbreaks faster.

More affordable with a price point of $20-$30 on average, per test.

A recent study shows sensitivity is secondary to frequency and fast turnaround time, showing how important rapid antigen testing is for controlling the pandemic.

6. What do experts say about rapid antigen tests?

Harvard University’s epidemiologist, Michael Mina, has been vocal in the media recently about the value of rapid antigen tests. As cited by the December 4, 2020 issue in New York magazine, in mid-November Mina argued that large-scale deployment of rapid antigen tests could stop the spread of COVID-19 by Christmas. He goes on to say, “it doesn’t matter if it was PCR or antigen testing — it’s the frequency that really matters. What we’ve seen is where there is frequency of testing, outbreaks just aren’t happening.”

*There are several cited examples where this has been seen in countries like, Slovakia. Citizens were asked to get tested every weekend for three weekends. After a few weeks of people doing so, incident levels dropped by 50 percent.

*Source: New York magazine, December 4, 2020.

7. If frequency is more important, does test sensitivity really matter?

Yes, sensitivity absolutely matters. However, the recent UC Boulder and Harvard study suggests that it is simply somewhat less important than other factors like frequency of testing and turnaround time. Sensitivity is also more important for individuals with very low levels of virus i.e. during very early stages of infection.

8. How should rapid antigen tests be used as part of a testing program?

Rapid antigen tests are best used when the chances of a positive result are high, for example when someone is symptomatic or in a high-risk living situation like a nursing home, university dorm, community settings. Because of how quickly these tests can be processed to yield a result, this allows a quick response to stop any possible transmission.

9. How long do you foresee the need for COVID-19 testing?

Even with a promising vaccine by Pfizer and German-based BioNTech, the need for ongoing COVID-19 testing will likely be encouraged by public health officials to continue into year-end 2021 and beyond. It’s possible, COVID-19 testing on some level is here to stay.

For example, I think we’ll see COVID-19 testing become a part of regular preventative health measures in settings such as schools, workplaces and other public health sectors. I also think more partnerships like that one between Meenta, US Wellness aznd Apricity Health will take-off. As part of these employer health programs, COVID-19 testing could become an employee or employer mandate, just like drug testing at some companies or vaccines for school.

10. How readily available are rapid antigen tests and where can I buy them? (See Table 2 below)

Good news and bad news. The good news — production of rapid antigen tests are increasing and so are the number of manufacturers expected to receive and seek FDA/EUA approval in the U.S. The bad news — there is a global and national shortage. Get them if and where you can. With that said, more good news…

Meenta’s COVID-19 marketplace has two rapid tests available for purchase. This first is Access Bio’s CareStart™ rapid test which is in supply now. Also, Meenta has been granted access to take pre-orders of the highly anticipated SD Biosensor rapid test, which expects FDA approval in January (see Table 2 for details on sensitivity and specificity for both).

11. What’s caused a shortage in these tests and why aren’t they $5?

The worldwide shortage of rapid antigen tests is due to a number of factors. First, the $5 rapid antigen tests announced in September, were initially designed for low-and middle-income countries by the World Health Organization and the Bill and Melinda Gates Foundation. The price point was designed to aid financially disadvantaged countries with access to affordable testing. The Gates Foundation purchased 120 million of these tests produced by Abbott Laboratories and Access Bio.

Abbott’s $5 rapid test sold out in the U.S. before it even hit the market. The U.S. government purchased 150 million before production was complete. Even with reports of 1 million tests being produced a day, Abbott continues to have a supply shortage. With a minimum order of 5,000 tests required, it also makes it hard for smaller and mid-size entities to gain access.

12. How many rapid tests are approved and available for purchase? (See Table 2 above)

Available for purchase NOW is Access Bio’s CareStart™ 10-minute rapid antigen test on Meenta’s marketplace

Right now, there are four rapid tests that have either obtained or awaiting FDA/EUA approval. Only Access Bio’s CareStart™ COVID-19 Antigen Test is available in limited supply nationwide, including Meenta’s marketplace.

Consultation

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