PCR Test vs. Rapid Antigen Test: The Importance of Choosing the Right One

Updated: Apr 5

The US has reported almost 80 million cases of COVID-19 since early March 2020. And these numbers keep going up.

That's why it's important to seek out testing for COVID as soon as you begin to experience symptoms of the pandemic-causing virus. The test ensures that you can take care of yourself in the event of a potential COVID infection. It also helps you take care of your community and loved ones.

But, there are two common types of COVID-19 tests: the PCR test and the rapid antigen test. This guide will explore the differences between the two types. With the right test, you can be certain you're getting the right diagnosis and the care you need.

What Is a PCR Test?

Considered the gold standard in COVID testing, PCR tests are the recommended tool of COVID detection. These are the tests that employers, airlines, or venues are usually looking for when requiring a negative COVID test.

PCR stands for polymerase chain reaction. Using this type of test, very small amounts of COVID-19 genetic material is detectable in human specimens.

According to the US Centers for Disease Control, the PCR test works by making copies of the coronavirus' genetic material to make them more detectable. Because of this ability to amplify, PCR tests are highly sensitive for COVID-19 diagnosis. This makes them useful for detecting all levels of virus infection, including infection of the more mild Omicron variant.

However, PCR tests aren't the best choice for all situations.

The Problem with PCR Tests

In some cases, PCR tests can turn up positive for people who are no longer contagious. Because they are so sensitive, they can cause you to test positive even three or four weeks after your recovery.

This means that after seven to 10 days of testing positive for COVID-19, PCR tests are no longer considered a useful tool for patients.

When To Use a PCR Test

PCR tests are most useful when used for the initial diagnosis of COVID-19. The best time to take one is shortly after a known or suspected exposure to the virus or after you begin experiencing symptoms.

Common COVID-19 symptoms include, but are not limited to:

  • Fever

  • Persistent cough

  • Excessive fatigue and tiredness

  • Loss of taste or smell

  • Shortness of breath or trouble breathing

  • Muscle aches and chills

  • Sore throat

  • Runny nose

  • Headache

  • Nausea, vomiting, or diarrhea

Symptoms usually appear 2 to 14 days after initial exposure to the virus.

Getting tested and diagnosed early is a key of maintaining public health. Knowing you have COVID can help you maintain the proper protocol to minimize its spread amongst your community.

A few things you should do to minimize spread after your initial diagnosis include:

  • Stay home for at least five days, per the CDC

  • Inform any recent close contacts of potential infection

  • Wear a face mask when interacting with others

  • Wash your hands for at least 20 seconds

A proper, early diagnosis is also key to keeping yourself safe. That way, you can receive the proper medical care that you need. Your doctor can give you the medicines, vitamins, and care instructions necessary to improve your chances of recovery.

Where To Get a PCR Test

To ensure you're getting the proper diagnosis, you need to make sure your PCR test comes from an accredited source.

The US Food and Drug Administration (FDA) has authorized several providers to administer PCR COVID tests. Some places you can get a test include:

  • Your doctor's office

  • Certain urgent care offices

  • Drive-through testing sites

  • Temporary pop-up testing sites

It is not recommended to go to an Emergency Room for COVID testing. This can overload ERs and make it difficult for drastically ill patients to get the care they need. If you want a quick in-office COVID test, try reaching out to an urgent care office or temporary testing site instead.

Tests such as the GeneIQ PCR COVID-19 and COVID Plus tests can provide you with quick, accurate results.

Most PCR tests are not available for at-home use. This is because they require a laboratory for analysis. If you want to take an at-home test, you'll need to get a rapid antigen test instead.

What Is a Rapid Antigen Test?

A rapid antigen test is a simpler, less sensitive method of covid testing. Unlike a PCR test, rapid antigen tests do not require the use of a laboratory to obtain results.

Instead, antigen tests look for pieces of SARS-CoV-2 proteins. Because SARS-CoV-2 is the virus that causes COVID-19, the presence of these proteins can confirm the existence of a COVID infection.

Antigen tests work similarly to pregnancy tests. The collected sample is placed upon a test strip. A colored line will alert the user that their test is, in fact, positive.

Samples are usually collected from nose swabs. However, throat swabs and cheek swabs are also used in some antigen tests.

Usually, results from rapid antigen tests are available within 10-15 minutes after collecting and applying the sample to the test strip. This is much faster than the 24–48-hour turnaround of PCR tests.

According to the CDC, rapid antigen tests are most effective during peak viral load. At this point in the infection, rapid antigen tests are thought to have "moderate to severe sensitivity."

Viral load is the amount of virus that is present in your body. It usually peaks about a week after the initial exposure. This is also usually when you are at the height of your symptoms.

However, though they are convenient, rapid antigen tests are not perfect for every situation.

When To Use a Rapid Antigen Test

Rapid antigen tests are much less sensitive than PCR tests in most cases. While it's possible they can detect an initial infection, they may also provide false-negative results in the early stages of the illness.

When used for initial infection, keep in mind that the result may be inaccurate. If you get a negative result but are experiencing symptoms or have recently faced a definite exposure, it is still a good idea to try and schedule a PCR test.

However, rapid antigen tests are still crucial. They are most useful for determining how long you may be contagious. Many doctors recommend you take a rapid antigen test near the end of your five-day isolation to determine if you are still carrying detectable, and potentially infections, levels of the virus.

Understanding the Timeline

If you are still testing positive on a rapid antigen test at the end of your five-day isolation, you should continue isolating until day 10 since symptoms appeared.

Even if you test negative after the five-day isolation, you should still wear a mask around others until day 10 since symptoms appeared. An estimated 31 percent of people were still contagious after the initial five-day isolation. Masking up will help to reduce the risk of community spread, while still allowing you to resume a bit of public life.

It is also a good idea to repeat your rapid antigen test the day after testing negative. If you receive another negative result, this is a pretty good indicator that you are likely no longer contagious.

And keep in mind that while antigen tests can give you a false negative result, they will very rarely give you a false positive. In most cases, you should treat a positive antigen test as a pretty good indicator that you do have COVID, and you are likely infectious.

Where To Get a Rapid Antigen Test

Rapid antigen tests are often found in the same clinical settings and testing sites as PCR tests. However, they are also easier to find for at-home use because they don't require the use of a laboratory.

You can purchase at-home rapid antigen tests from most pharmacies or online for at-home delivery. The availability and ease of rapid antigen tests are another reason they are a popular choice and a useful tool for detecting the presence of continued infection.

Keep in mind, however, that at-home COVID tests are usually not covered by insurance. Whereas PCR tests and testing-site antigen tests are usually offered free of charge, at-home tests can run you an average of $24-$38.

It is also incredibly important to follow the instructions for your home test very carefully. A test that is incorrectly performed can give you a false result, or an invalid result. In the case of the latter, you'll have to repeat the test and those costs can add up.

Preventing the Spread

Testing and vaccinations are perhaps the two most important things you can do to help prevent the spread of COVID-19. However, they aren't the only things you can do.

Even as mask mandates and other COVID restrictions begin to ease, you can still do a few simple things to keep yourself and your community safe. These include:

  • Wearing a mask, especially in crowded areas

  • Maintaining social distance -- at least 6 feet

  • Wash your hands often with soap and water

  • Use an alcohol-based (at least 60 percent) hand sanitizer after coming in contact with other people or public surfaces

  • Avoid touching your face, especially mouth, nose, and eyes

  • Stay home when you're sick

  • Avoid close contact with sick people when you're healthy

  • Cover coughs and sneezes with a tissue

  • Frequently disinfected surfaces that are common use

You should stay in contact with your healthcare provider. They can not only give you tips on keeping yourself and others safe, but they can offer specific guidance on what to do in the event of potential or confirmed COVID infection.

Your healthcare provider can also advise on which COVID test is most useful for your situation and when you should take these tests.

FAQ: Can Tests Distinguish Between Variants?

The short answer is ‘no’, neither the PCR test nor the rapid antigen test can tell you which variant of COVID you might have. Determining the specific variant requires genetic testing, which is intensive and is only possible to complete in a lab setting.

Instead, random positive COVID samples across the country are sent to specialized labs where they can be anonymously tested. This helps scientists, public health officials, and community leaders determine the threat levels of each specific variant.

Hearing that X-number of infections come from a certain variant is entirely based on estimation. For example, researchers estimate that 95 percent of COVID cases in January 2022 came from the Omicron variant.

FAQ: Can These Tests Distinguish Between COVID and the Flu?

It's no secret that COVID and the flu have similar symptoms. They are both respiratory viruses that can present very similarly, especially in the early stages of infection when testing is most crucial.

Though current PCR and rapid antigen tests won't be able to tell you if you have the flu, there are other specialized tests that can distinguish the difference. In fact, these tests also look for RSV (respiratory syncytial virus) in addition to COVID and influenza, like GeneIQ’s COVID Plus test.

These tests are available primarily through doctor's offices so that they can be sent off to specialized labs. Results are typically available within 24-48 hours. Some doctor's offices may only have them during flu season, however.

Protecting the Community One Test at a Time

COVID can be a confusing virus, that's why it's best to get vaccinated, get tested, and keep yourself and your community as safe as possible. A rapid antigen test or PCR test can be your first line of defense in protecting yourself and your loved ones.

Contact us at GeneIQ to learn more about our top-of-the-line COVID tests. Our tests provide cutting-edge diagnostic tools to detect COVID as soon as possible, putting you on the path toward a quick recovery.

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