Testing for COVID-19 in 2021 and Beyond
Nearly two years into the COVID-19 pandemic, it seems like we may be back to square one but with one main difference: the availability of vaccines. The discovery of new variants that are highly contagious, Delta and Omicron, coupled with the holiday season has both positivity and testing rates skyrocketing.
Recently, President Biden announced that private health insurance plans will soon reimburse people who buy at-home rapid tests for COVID. The announcement comes at a time when positivity rates for the virus increase each day and is one in a series of moves the White House is planning to “encourage better detection and prevention of COVID-19 this winter.”
While these over-the-counter, at-home options are convenient, they might not tell the complete story in terms of diagnosis. When used correctly, these tests are a good measure of detecting people carrying high levels of the virus, or those with symptoms. These tests have their limitations but are an important public health tool when used correctly.
In the “first wave” of the pandemic, actions to minimize its spread (remember “flatten the curve”) included lockdowns and shutdowns. Now that vaccines and booster shots are available, the focus is now on increasing vaccination rates and testing. In a blog from 2020, we examined the different types of COVID testing that are available. If you think you have been exposed to someone with COVID-19 or are experiencing symptoms, it is important to contact your healthcare professional to determine the proper course of action and minimize potential spread.
Types of Tests: PCR vs. Antigen
Diagnostic tests are used to identify active coronavirus infections. These tests are administered to patients who are currently experiencing COVID-19 symptoms, or who believe they have been recently exposed to COVID-19. When a patient receives a positive diagnostic result, it means they have an active infection and need to take steps to quarantine and isolate from others to keep from spreading the virus.
Currently, there are two main types of diagnostic tests being used for COVID-19:
1. COVID-19 PCR Testing
Polymerase chain reaction (PCR) tests make up the majority of tests used to diagnose patients with active COVID-19 infections. This type of test is also known as a viral test, molecular test, or nucleic acid amplification test (NAAT).
The COVID-19 PCR test works by detecting the genetic material of the virus in a fluid sample collected from the patient. A nasal or throat swab is the usual method of sample collection.
If the test is completed onsite, the results could be available to the patient in minutes. However, due to the volume of testing demand, most samples are sent to offsite labs. Results are usually available to the patient between one day and one week after testing.
The COVID-19 PCR test is considered to be highly accurate at diagnosing active infections and usually does not need to be repeated. Keep in mind that this test cannot tell whether or not a patient has been infected in the past, only whether they are currently infected.
2. COVID-19 Antigen Testing
Antigen testing is a more recently developed COVID-19 test that detects certain proteins on the surface of the virus. This type of test is also known as a rapid diagnostic test.
Much like the PCR test, the antigen test is performed by collecting a patient sample via nasal or throat swab. Antigen tests are faster and less expensive than PCR tests; there is no need to send the sample to an offsite lab, so the results are available within just a few minutes.
Compared to PCR tests, antigen testing is not quite as accurate. Some at-home antigen tests have a sensitivity of around 85 percent, meaning they will prove accurate in 85 percent of people who are infected with COVID. While this may seem fairly good, the tests are more sensitive in symptomatic individuals during the first week of symptoms. A person could test negative via an at-home antigen test but have an active infection (false negative) sans symptoms (asymptomatic).
If a patient is experiencing COVID-19 symptoms but receives a negative rapid test result, their physician may retest the patient using the PCR test to confirm or deny the original result.
Antibody tests are used to determine whether or not a healthy patient has been infected by COVID-19 in the past. This type of test is also known as a serology test or a serological test.
COVID-19 antibody tests are performed by collecting a blood sample from the patient (usually via finger prick, or sometimes by drawing blood from a vein in the arm), and testing that blood sample to detect the presence of certain antibodies developed after exposure to coronavirus.
Unlike the two diagnostic tests mentioned above, antibody tests cannot diagnose an active coronavirus infection at the time of the test, or be used as evidence that a patient does not currently have COVID-19. This is because antibodies take several days or weeks to develop after the infection, which is why one is not considered “fully vaccinated” until at least two weeks after the second dose of the vaccine.
Why is antibody testing important? Understanding the true number of patients who have been infected with COVID-19 is important for epidemiologists who are researching the spread and scale of the virus. This information will be essential in planning for future pandemics.
Those who have previously been infected with COVID-19 were thought to have a certain level of immunity against future infection, but that may not be the case. There have been many instances of people becoming reinfected both after initial infection and after receiving the vaccine. These cases are referred to as “breakthrough” cases.
If you are experiencing symptoms of COVID-19 testing, may have been exposed to the virus, or believe you have recovered from the virus, ask your healthcare provider about the best COVID-19 testing option for you.
Learn how My One Medical Source® (MOMS) is working to meet the demand for COVID-19 testing at our MAPS locations.