Rapid COVID-19 tests explained
Medically reviewed by Everlywell Medical Communications & Publications Manager on June 11, 2021. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
Even with a highly efficacious vaccine, we still have a lot to learn about SARS-CoV-2 , and there are still plenty of people who aren’t yet vaccinated, particularly children under the age of 12. The risk that a fully vaccinated person could become infected is very low; however, any fully vaccinated person who experiences symptoms consistent with COVID-19 should isolate themselves and should seek help from a healthcare provider on whether they should consider getting tested for COVID-19. There’s also the potential for further strain mutations.
This is why testing is still an essential component for managing COVID-19. Testing provides diagnoses for individual patients, along with information about potential outbreaks. Ongoing testing also gives us integral information about the virus itself, which can help us determine new methods for treating and preventing infections. That information can also help us plan and prepare for future pandemics and health crises, even those unrelated to COVID-19.
Rapid antigen COVID-19 tests are one of the most common forms of testing, but the most pertinent question with any type of test is accuracy. How accurate is the rapid antigen COVID-19 test? Read on to learn more.
What is the Rapid COVID-19 Test?
There are a handful of different tests available. Diagnostic tests, which include molecular tests and antigen COVID-19 tests, are designed for diagnosing current infections and potential infections from the recent past. Antibody tests detect COVID-19 antibodies in the system, which can suggest that you previously had the infection. However, the exact nature, role, and extent of COVID-19 antibodies still require further research.
Your immune system typically detects antigens on viruses, which results in the production of antibodies. Molecular tests, which include PCR tests, detect the genetic material of a virus. So as you can see, there are distinct differences between the rapid antigen test vs. molecular tests, like the PCR test.
What’s more, rapid antigen tests provide a quick turnaround on results. Whereas most molecular tests require sending test samples to a lab and waiting several days for the results, rapid antigen tests can be processed at the point of care, providing results in about 15 to 30 minutes on average. Considering the unknown nature of COVID-19 and the way that the disease can progress quite quickly, knowing your diagnosis of the coronavirus infection within a few minutes versus a few days could make a huge difference in your overall care as well as curb the risk of community spread.
The FDA has approved the use of rapid PCR tests. These tests offer the same process as a molecular test but with the quick turnaround time of antigen tests. For the sake of this article, “rapid test” refers to the more common antigen test.
Getting Test Samples
While they have different processing times and differ in what they detect, the rapid antigen test and the molecular test generally have the same process on a patient level. Obtaining a sample requires the use of a nasal swab. The swab is used to collect an upper respiratory tract sample from the nasal passage and/or nasopharynx. Specimens taken from the nasopharynx tend to have a higher viral concentration. Insufficient specimen collection, may result in limited amounts of viral genetic material for detection, which can impact the test’s results.
The swab is inserted into a nostril, twisted a few times, and removed. The process is then repeated in the other nostril. You may feel the urge to sneeze, and getting a swab inserted deep into the nasopharynx can feel strange and uncomfortable.
Some tests may also use saliva samples. Producing saliva for a test can take a lot of time, and some people have trouble producing enough saliva.
Benefits of Rapid Antigen Tests
Of course, the biggest advantage to a rapid antigen test is that they take such little time, from obtaining your sample to getting your results back. Waiting just 15-30 minutes, compared to potentially up to a week, makes all the difference. A lot of that comes down to the ease of use. Rapid tests can be used at the point of care, meaning they can be used in healthcare providers’ offices, clinics, and emergency room environments.
The affordability and lack of clunky parts and pieces ultimately equate to greater accessibility for both patients and caregivers. Greater accessibility means more people who want or need tests can easily obtain them. That also means more data and information for public health officials and organizations, which then means better care for communities.
Rapid antigen testing COVID-19 kits, like those offered by Everlywell, are also available at a consumer level. This allows people to obtain test samples from the comfort of their homes.
Rapid Antigen COVID-19 Tests and Accuracy
It’s important to note that no test is accurate 100 percent of the time. Even molecular tests, which are considered the hallmark of COVID-19 tests and used as a reference standard when assessing the clinical performance of new diagnostic tests, are imperfect. There are many factors at play, from the test procedures to the viral load.
If your antigen test shows positive results, it is very likely you have an infection and should self-isolate at home per CDC recommendations to prevent spreading the virus to others. If your results are positive but you don’t show any symptoms or otherwise have no reason to believe that you have been infected (like, for example, you have been vaccinated and maintain social distance), your healthcare provider may recommend a PCR test to confirm your positive result.
Antigen tests generally require a much higher viral load or concentration than molecular tests. If you have a lower viral load, the test may be unable to detect an infection. A low viral load can come at the beginning of an infection, when the virus is still replicating, or at the end of the course of an infection.
If your rapid test comes back with a negative result, but you are experiencing symptoms of COVID-19, it’s recommended to follow up with your healthcare provider who may recommend a molecular test to confirm the results. Alternatively, they may recommend another antigen test a few days later, when the viral load is presumably higher.
If you experience any symptoms, even after being vaccinated, or otherwise believe you may have COVID-19, it’s highly recommended that you get tested. It can provide you with peace of mind, and it can provide necessary information for public health.
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References
- COVID-19 Rapid Tests: Accuracy, Types, and Where to Find Them. GoodRx. [URL](https://www.goodrx.com/blog/covid-19-rapid-test/). Accessed June 11, 2021.