Jan 2

Jan 2 Choosing Effective COVID-19 Testing

Understanding The Difference Between COVID-19 Testing Options

When you think about efforts to fight the spread of COVID-19, vaccinations, hand washing and masking likely come to mind. However, one important effort that must remain the first line of defense is effective testing. With the holiday season just behind us, we cannot let our guards down. Testing, combined with other defensive measures, is essential to keeping ourselves and our loved ones safe.

Since the World Health Organization (WHO) declared COVID-19 a global pandemic in March 2020, medical experts and government leaders have worked together to make different types of testing options easily accessible to the public.

You may not realize there are different types of tests, so what is available to you?

The two main types of tests authorized for detecting COVID-19 are polymerase chain reaction (PCR) tests and antigen tests. Here is what you need to know about both:

Antigen tests

If you have ever taken a rapid strep test or pregnancy test, antigen tests work similarly ^[1]. Also referred to as rapid tests or rapid antigen tests, these tests work by quickly identifying protein fragments from a virus — these are the antigens — and providing test results in about 15 minutes^[2].

Despite being fast, antigen tests can be less accurate than other testing options because they are less sensitive, meaning that some people might incorrectly be told they don’t have the virus¹.

Because no special equipment is needed, antigen tests may be performed in various community settings or at home. This convenience has made antigen tests, particularly at-home options, popular when quick results are needed, as when returning to an office or preparing for an event like a vacation.

However, there is more room for error when self-testing, as opposed to having a test administered by a trained professional². Further, at-home antigen tests are most accurate if COVID-19 symptoms are present and may require the use of several tests to confirm a diagnosis^[3]. It is also important to always follow the manufacturer's directions.

Antigen test overview

When to take it: When in need of results quickly

Speed: Results usually available in 15 minutes

Chance of user error: High

Ease of use: Doesn’t require equipment or chemicals; easy to use at home or point of care

Effectiveness on variants: Low

PCR tests

PCR tests are also referred to as molecular tests, viral RNA tests or nucleic acid tests¹. These require special equipment and are typically sent to a lab, with results often available within 24 hours, depending on location. Some PCR tests provide results in just 20 minutes, however, these tests are mostly available in healthcare environments, such as hospitals².

Why would someone use a test that takes longer to get results? The answer: accuracy.

PCR tests have remained a touchstone in diagnostics due to their heightened accuracy over antigen tests¹. They are highly sensitive and can detect very small amounts of virus genetic material in a sample, such as viral DNA¹. These tests have a sensitivity of about 98%, much higher than comparative data for antigen tests¹. This is why PCR tests can detect active infections nearly every time, and it is rare for someone uninfected to receive a positive test¹.

PCR test overview

When to take it: When in need of extremely accurate results

Speed: Results usually take 24 hours; may require an appointment

Chance of error: Low

Ease of use: Requires equipment, chemicals and trained specialists; point-of-care options available but limited

Effectiveness on variants: High

The future of COVID-19 testing

With vaccination rates increasing and booster shots recently becoming available, we are seeing some normalcy return to our lives. However, as restrictions ease, people are traveling more and starting to return to routine life activities, making people more vulnerable to infection.

As the pandemic evolves and holiday gatherings commence, complementary testing options can make effectively screening for COVID-19 even easier. This may include combining antigen and PCR testing for identifying present COVID-19 infections, antibody tests for evaluating past exposure, and multiplex tests, which tests for more than one disease, such as flu and COVID-19.

To learn more information about COVID-19 testing options, visit Roche Diagnostics Corporation’s storytelling hub.

^[1] ^{https://www.yalemedicine.org/news/which-covid-test-is-accurate}^{(Last accessed November 22 2021)}

^[2] ^{https://www.mayoclinic.org/diseases-conditions/coronavirus/expert-answers/covid-antibody-tests/faq-20484429} ^{(Last accessed November 22 2021)}

^[3] ^{https://www.scientificamerican.com/article/the-smartest-way-to-use-rapid-at-home-covid-tests1/} ^{(Last accessed November 22 2021)}