Diagnostic testing for active COVID-19 is confusing. Not only are there different types of tests, health care professionals can get samples by swabbing different areas – from your nose, mouth, throat and more. Dr. Rossana Rosa, Infectious Disease Specialist for UnityPoint Health, helps us understand your testing options and why it’s important for you to know the latest testing developments.
Which COVID-19 Test Should I Get?
There are two diagnostic tests that identify active COVID-19 infection in people. A third type of test, an antibody test, works to find evidence you’ve previously had COVID-19.
How Do Antigen Tests for COVID Work?
An antigen test detects proteins produced by the virus. These tests are less sensitive and often less accurate. Antigen tests are performed with nose or throat swabs to search for an active COVID-19 infection.
- Tests for: Active COVID-19 infection
- Also known as: Rapid test
- Results timeline: 1 hour or less
How Do Molecular COVID Tests Work?
A molecular test includes the rt-PCR test, commonly called PCR test. Molecular tests detect the genetic material that makes up the virus. These tests are very sensitive and often more accurate. Molecular tests look at samples from the nose, saliva, sputum (saliva and mucus) or nasopharyngeal (area right past your nostril) to search for an active COVID-19 infection.
“Molecular tests pick up very small fragments of the virus, even beyond the point that someone is contagious or ill, but, perhaps, you are still sheading the virus. That’s why you can get a positive test result from a molecular test, even though you might not have an active COVID-19 infection.” Dr. Rosa says.
- Tests for: Active COVID-19 infection
- Also known as: PCR test
- Results timeline: 24 to 48 hours or more depending on demand
How Do Antibody COVID Tests Work?
An antibody test does not test for active COVID-19 infection. Instead, an antibody (or serology) test uses a blood sample to determine if you've developed antibodies against the COVID-19 virus, usually 14 days after the infection has occurred. If antibodies are identified, it’s a sign you might have previously contracted COVID-19.
- Tests for: Prior COVID-19 infection
- Also known as: Serology test
- Results timeline: Several days, even up to a week
If you’ve had a COVID-19 vaccine, an antibody test may also pick up on the antibodies you’ve developed from the vaccine, although this will depend on the brand of antibody test you got.
Where Can I get a COVID-19 Test?
If you’re still not sure which COVID-19 test you need or where to get tested, call your health care provider or clinic for guidance. Testing is also available at walk-in clinics like UnityPoint Clinic – Urgent Care or UnityPoint Clinic – Express. If you start to feel very ill and need emergent medical attention, go to the emergency department or call 911. In the Emergency Department, you can be assessed for symptoms and be tested for COVID-19, if needed.
Why Are There So Many Coronavirus Test Types?
“There have always been different options for testing different respiratory viruses. We are now just more aware of what they are, since there is more testing occurring in our communities during this pandemic,” Dr. Rosa says.
What COVID-19 Test is Most Accurate?
Dr. Rosa says what test you use all depends on your situation.
“If a test is done because someone has symptoms of COVID-19, then it’s best to get a PCR test (molecular test), because it is the most sensitive. It will detect even the smallest fragments of the virus. If a person with symptoms gets a negative result with an antigen test, then it would need to be confirmed with a PCR test. On the other hand, if a test is done because someone was exposed, but doesn’t have symptoms, a less sensitive type of test could be used, whether molecular or antigen. However, in this last scenario it’s important to remember that even if you receive a negative test result you can still develop an infection later, and so you still need to follow local public health guidelines on quarantine duration,” Dr. Rosa says.
If you haven’t been exposed and don’t have symptoms, it’s referred to as testing for “contagiousness.” She says this strategy is used in some places like nursing homes, school districts and by sports teams. Testing to diagnose active disease as opposed to testing to detect contagiousness are two very different things.
Can Current COVID-19 Tests Identify All the Emerging and Future Variants?
New emerging variants of the COVID-19 virus have caused many to question if the current test can still identify all the different variants. The good news is most FDA approved molecular tests identify COVID infection by searching for evidence of more than one part of the virus.
“Health care officials are constantly checking to make sure their tools are picking up both of the targets. The current PCR tests look at an area on the spike protein. The variants are impacting a different area of the spike protein that is not targeted by the tests. That’s why our current tests still work. Antigen tests shouldn’t be impacted because those look for proteins, which aren’t impacted by the variants,” Dr. Rosa says.
How Long Does It Take to Get COVID-19 Test Results?
Usually, antigen tests will give you results in less than an hour. Molecular tests take longer. For PCR, which is a common type of molecular test, results typically return in 24-48 hours. However, in times of high demand, results may be delayed up to seven days. Timing depends on how many tests the lab is handling and how quickly technicians can get to your sample. If you get a test at UnityPoint Health, you can sign up for a MyUnityPoint account to view your results as soon as they are available.
What Happens to My COVID-19 Test Sample?
Antigen tests are put into relatively small machines or “cartridges.” It works similarly to a pregnancy test, which is why you get a rapid result.
“For PCR tests, the sample is taken to a central lab and prepared by technicians who put samples in a machine called a thermocycler. These machines multiply the genetic material several times, sort of like making copies on a copy machine, to determine if any virus is present.”
When Should I Get Tested for COVID-19?
If you have symptoms consistent with COVID-19, you’ve had a high-risk exposure (within six feet, for 15 minutes or more) to the virus and/or testing is advised by your health care provider or local/state department of public health.
Symptoms of COVID-19, as identified by the CDC, include:
- Fever or chills
- Shortness of breath or difficulty breathing
- Muscle or body aches
- New loss of taste or smell
- Sore throat
- Congestion or runny nose
- Nausea or vomiting
Should I Get Tested Before or After Travel?
The CDC says you should still avoid traveling as it increases your risk of getting and spreading COVID-19. However, if you choose to travel, follow these CDC testing recommendations:
- Get tested one to three days before your trip. Keep your results on hand for your trip. If you test positive do not travel.
- Check travel restrictions before you go. Some state, local and territorial governments may have testing or other virus-related requirements.
- Consider getting tested three to five days after your return from your trip and self-quarantine for a full seven days, even if your test is negative. If you don’t get tested, quarantine for 10 days following travel.
Why Aren’t Asymptomatic Test Results Reliable?
If you’ve been exposed to COVID-19, you can begin showing symptoms any time within the virus’ 14-day incubation period. If, for example, you don’t have symptoms on day three following exposure and get a COVID-19 test your results only apply to that day. You could still go on to develop the infection.
If you have been exposed, the best advice is to quarantine. For the least amount of risk, the CDC suggests a quarantine period of 14 days. However, following additional research, the CDC released two additional quarantine options in December 2020 in order to help those missing work. The first option is dropping the quarantine time to 10 days with no COVID-19 test. Or there’s a seven-day quarantine option, which includes receiving either an antigen or molecular test on, or in the 48 hours before, day seven of quarantine.
What Does My COVID-19 Test Result Mean?
Test results for antigen or molecular tests can come back in two ways:
- Positive. You have been infected.
- Negative. You are not currently infected.
However, Dr. Rosa says your test could be a false negative or a false positive.
- False negative. You are infected, but the test says you are not infected.
- False positive. You are not infected, but the test says you are infected.
If you think you’ve received an inaccurate test result, discuss it with your doctor. For example, you get a negative test result, but you have symptoms consistent with COVID-19. Your health care provider might suggest taking a second test to confirm your results.
When Will COVID-19 Testing Change?
COVID-19 testing is rapidly changing.
“There is some technology in development that would allow you to test for the virus at home using strips. But it’s not widely available yet. It’s important for everyone to stay up-to-date on the latest recommendations and advances to make the best use of the science and technology to reduce the spread of COVID-19.”