VERIFY Fact Sheet: COVID-19 testing

Here’s a breakdown of the different types of COVID-19 tests, how variants are identified and the accuracy of some at-home tests.

Throughout the COVID-19 pandemic, testing has been one of the critical tools available to limit the spread of the virus. A reliable test can alert someone that they’re infected with the virus that causes COVID-19 and need to limit their exposure to others.

But many people still have questions about testing. So, the VERIFY team gathered information from multiple sources to provide the facts about COVID-19 testing in the United States.

THE SOURCES

FAST FACTS

  • Rapid vs. PCR tests: These are the two types of COVID-19 diagnostic tests in the U.S. PCR tests are the most accurate but results typically take days. Rapid tests are less accurate, typically in the 80% range, but results are available in minutes.
  • Identifying variants: None of the authorized diagnostic tests in the U.S. identify variants of COVID-19. Variants are identified through genomic sequencing, a lab process that decodes the genes of the virus that causes COVID-19.
  • When to get tested: People generally should get tested if they have symptoms of COVID-19 or had close contact with someone who has COVID-19.

WHAT WE KNOW

There are two types of tests used to diagnose COVID-19

They are antigen and molecular tests.

An antigen test is more commonly known as a rapid test because results can be available in minutes. This type of test can detect specific proteins made by the SARS-CoV-2 virus that causes COVID-19, according to the Food and Drug Administration (FDA).

Molecular tests, which are often polymerase chain reaction (PCR) tests, involve a lab process that can detect the genetic material of SARS-CoV-2, the National Library of Medicine says. This process typically takes days, which is why it takes 48-72 hours to get results from a PCR test.

PCR tests are more sensitive than antigen tests, meaning they are more likely to accurately identify a COVID-19 case. For that reason, the PCR test is considered the “gold standard” for diagnosing COVID-19, according to the Cleveland Clinic.

Antibody tests should not be used to identify a current COVID-19 infection

These tests can detect antibodies made by the immune system in response to a COVID-19 infection. So, they can indicate whether you’ve previously been infected with COVID-19. But they are not used to diagnose COVID-19.

The Centers for Disease Control and Prevention (CDC) does not recommend using antibody tests to determine:

  • If you have a current infection.
  • If you have immunity to SARS-CoV-2 following COVID-19 vaccination.
  • Whether you need to get vaccinated if you are not fully vaccinated.
  • Whether you need to quarantine after a known or suspected exposure to COVID-19.

The CDC says these people should get tested for COVID-19

  • People who have symptoms of COVID-19.
  • People who have come into close contact with someone with COVID-19:
    • Fully vaccinated people should be tested 5–7 days after their last exposure.
    • People who are not fully vaccinated should get tested immediately when they find out they are a close contact. If their test result is negative, they should get tested again 5–7 days after their last exposure or immediately if symptoms develop.
  • People not fully vaccinated with COVID-19 vaccine who are prioritized for expanded community screening for COVID-19.
  • People not fully vaccinated with COVID-19 vaccine who have been asked or referred to get testing by their school, workplace, healthcare provider, state, tribal, local or territorial health department.

The CDC has a tool on its website that can help you decide on whether to get tested.

COVID-19 tests don’t identify variants

The tests are only designed to identify whether someone has COVID-19.

Variants are identified through genomic sequencing, a lab process that decodes the genes of the SARS-CoV-2 virus. This identifies characteristics of the SARS-CoV-2 virus to determine which variant it is. The Texas Department of State Health Services says not all positive COVID-19 cases go through genome sequencing. In November 2021, CDC director Dr. Rochelle Walensky said the U.S. was sequencing about 80,000 samples per week.

Related from VERIFY: Yes, the delta variant can be detected through genomic sequencing, but that's not the test you get at a clinic

You can test positive for COVID-19 on PCR tests weeks after you were infected

But that doesn’t mean you’re still contagious.

While the high sensitivity of PCR tests is reliable for first diagnosing people with COVID-19, it’s far less reliable for determining if someone is still infectious with the virus.

“Because the PCR test is so sensitive, it can detect very small amounts of virus material,” the Cleveland Clinic explains. “This means that the test can continue to detect fragments of SARS-CoV-2 virus even after you’ve recovered from COVID-19 and are no longer contagious.”

Fragments of the virus material can be detected three months later, according to the University of Texas Southwestern Medical Center. Health agencies in Canada and the United Kingdom also recognize that PCR tests can have positive results three months after a person was initially diagnosed with COVID-19.

The CDC says no studies have found evidence that people who continue to test positive for COVID-19 weeks after they’ve recovered transmit the virus to others.

More from VERIFY: Yes, you can test positive for COVID-19 on PCR tests for up to 12 weeks after infection

At-home rapid tests are less accurate than PCR tests

Several at-home rapid antigen tests have been shown in studies to correctly identify COVID-19 cases at least 80% of the time.

The Abbot BinaxNOW rapid test correctly identified a positive COVID-19 case 84% of the time, according to a clinical trial submitted to the FDA. The QuickVue At-Home OTC COVID-19 Test, gave a correct positive result 83% of the time compared to a PCR test. The CareStart COVID-19 Antigen Home Test was 87% accurate in a study.

Dr. Saralyn Mark, the COVID-19 lead for the American Medical Women’s Association, told VERIFY in October 2021 that rapid tests tend to be more accurate when a person is symptomatic because they likely have a higher viral load.

The FDA has a list of authorized at-home tests on its website.

The federal government is buying at-home tests that people can receive for free

In December, President Joe Biden said the federal government plans to purchase 500 million at-home rapid tests with delivery starting in January. But people will need to request a test in order to receive one.

“We’ll be getting these tests to Americans for free,” Biden said. “And we’ll have websites where you can get them delivered to your home.

The website where people can sign up for delivery of a free at-home test from the federal government has not been released.

Tests can also be purchased in stores and online. Prices vary, but each individual test typically costs between $10 and $25.

More from VERIFY: Yes, you’ll need to make a request to get a free at-home COVID-19 test from the government

   

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