SDX Guides

Covid-19 Rapid Tests: Antigen vs. PCR Tests

Have you been experiencing symptoms of COVID-19?

Do you have upcoming travel plans that require negative covid test results? In this blog we will be uncovering key components of two COVID-19 tests that are currently available. We will highlight the similarities and differences in Antigen vs PCR testing, test accuracy, travel requirements, and how the test procedures differ.  Here at  SDxLabs, we offer PCR (Polymerase Chain Reaction) tests because they hit the sweet spot between speed and accuracy.

In this blog - we'll take a look at when and why you should use each test. Notably - recent improvements to Antigen tests have made them a hugely valuable tool in the fight against COVID-19 and helped carve out a niche where they're actually preferred over PCR tests. Read on to find out why.

The two most common types of COVID tests currently on the market are viral tests, which tell you if the infection is currently in your body, and antibody tests which determine if you have been previously infected.

Before we dive into the blog: If you believe you have been exposed to COVID-19, it is urgent that you get tested and quarantine to prevent the spread of the disease. Exposure includes coming in close contact (within 6 feet of someone for a cumulative total of 15 minutes or more over a 24-hour period) with someone who has tested positive for COVID-19 (CDC). Quarantine is also recommended if you have not been fully vaccinated or are experiencing symptoms.

Accuracy remains the gold standard for COVID-19 testing.

When looking to get rapid testing for COVID, you want to get the test that is most accurate. This blog will explain why PCR testing is the most reliable COVID-19 testing option.  

Antigen tests have correctly identified the COVID-19 infection in an average of 72% of people with symptoms and 58% without symptoms. Out of those results, it was found that an average of 78% of cases were confirmed positive antigen tests. In a study conducted in January 2021, PCR COVID tests were found to have a much higher accuracy rate at roughly 97% and have a false positive testing rate of less than 0.01% (Healthline).  

So what does this mean for you? When you're symptomatic - an antigen test is a quick and relatively accurate means of assessing your current risk level. The CDC currently recommends that you use antigen tests as a first line of defense and then confirm the results with a PCR test. 

When should you get tested?

Antigen Tests: 

To increase the chance of virus detection using Antigen rapid tests, public health experts recommend that individuals who think they may have COVID-19 wait a few days before getting tested. When a person is highly symptomatic, the accuracy of antigen tests increases. During the early stages, it is less likely for an individual to become aware of the infection, meaning you could have been exposed, but are not yet experiencing symptoms. It is at this time that the individual is most contagious. Even if you do not ever experience symptoms, an infected individual can still spread the virus via air and through droplets of bodily fluid.

PCR Tests:

PCR tests on the other hand are accurate and the most relevant during the early stages of the virus; the PCR rapid test will detect even the smallest amounts of COVID-19 found in the body. However, due to the test’s sensitivity, patients may still get positive PCR test results for weeks after they have the virus, typically outside the CDC recommended windows for quarantining.  As of Early 2022: The CDC has updated guidance to now recommend Antigen tests as an alternative to waiting for a negative PCR result. Please make sure that you're keeping up with (and following) their guidance! 

Visit SDxLabs to get accurate PCR Covid testing near you.  

Testing for travel - which test is best?

While in some cases antigen tests are acceptable for travel, most places require a negative result from a PCR test. According to the CDC, in order to travel internationally, a COVID-19 viral test is required no more than 24 hours before air travel. For domestic flights, vaccine requirements depend on the airline. It is recommended that non-vaccinated guests get a rapid covid test 1-3 days prior to travel as well as upon return.   

Antigen tests can generate test results in as little as 15 minutes. Though given the speed of the testing, antigen tests have a much higher chance of missing an active infection. With PCR tests, people typically receive results in 1-3 days.

  • When planning to travel, check your destination’s COVID-19 situation as restrictions may vary according to state, local, and territorial governments.
  • Masks are required to be worn over mouth and nose for travel on planes, buses, trains, and other forms of public transportation regardless of your vaccination status.
  • If you are not fully vaccinated, it is recommended that you get tested before and after your trip.
  • Check for  COVID-19 testing locations near you.
  • Note that you do NOT need to get tested or quarantine if you have recovered from COVID-19 within the past 90 days (about 3 months). If symptoms arise after travel, isolate, and call/visit our website to book your PCR rapid testing with SDxLabs.  

This information is correct as of February 2022 - please check for updates as this is changing week-to-week. 

PCR vs Antigen Tests - Ease of Testing

PCR tests are effortless for the individual being tested, but much more complicated for health care workers performing the rapid test. The biggest difference between PCR and Antigen tests, as far as patients are concerned, is the fact that most PCR tests must be done in person, or at the very least you will have to wait for the sample to be processed by a lab before you receive results.
Samples can be collected from the patient using a nasal swab or saliva specimen.

Nasal Swab Specimen:

Nasal swabs used to be the primary method for collecting fluid for COVID testing. A fluid sample is gathered by inserting a 6-inch-long nasal swab (nasopharyngeal swab) into your nostril. A healthcare worker collects fluid from the back of your nose by rotating the swab around the nasal wall in a circular motion for 15 seconds. A shorter nasal swab (mid-turbinate swab) can also be used to obtain a fluid sample.

Saliva Specimen:

An individual may not eat, drink, chew gum, smoke/vape or brush teeth for at least 30 minutes prior to collecting saliva. This testing method is equally effective as the standard nasopharyngeal swab. It also offers an improvement as people can collect their own sample with minimal discomfort—simply spit into a sterile tube several times until reaching the fill line and tightly screw on the cap until the testing liquid falls into the saliva. Shake vigorously for 5 seconds and turn in sample to be tested. This process is noninvasive and naturally the preferred testing method for patients.


Further explanation of our PCR rapid testing can be found on our website.

Though less accurate, the total procedure time for conducting an Antigen rapid test is much shorter than the PCR test procedure.

First, a sample is treated with a liquid mixture of salt and soap which is used to break apart cells and other particles. The liquid is then applied to a test strip containing antibodies specific to the virus. If antibodies from the sample bind to the Covid-19 antigens, the test strip will display positive results indicated by a colored line.  Overall, while the saliva testing procedure is most preferred, both tests should be relatively painless and easy to conduct. 

*Please note: A COVID-19 vaccination will not affect the results of a PCR or Antigen rapid COVID test. Vaccines may contain only a small portion of mRNA which cannot make sufficient copies of itself to be detected in even a PCR test. 

So, Antigen vs PCR tests, which one is right for you?

Many experts would agree that a PCR test is the way to go for precise COVID-19 test results. The PCR Viral Test procedure is practically painless, further accepted for travel, can be conducted at-home or in lab, and most importantly, it is most accurate.  Understanding the strengths and limitations of both the Antigen and PCR COVID-19 tests can help gain control over the pandemic. The next time you get a COVID-19 rapid test, be sure to choose the one that is right for you. 

Remember: when in doubt It’s better to be safe than sorry - schedule a test today and together, we can make this pandemic go down in history!  

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