The situation has improved significantly since then, due in part to the increasing availability of antigen tests, also known as rapid tests. In many parts of the country, getting one of these tests can be as simple as picking up a do-it-yourself kit at the drugstore and waiting 15 minutes or so for results. New testing technologies are appearing as companies continue to innovate. The latest device to receive the okay from the U.S. Food and Drug Administration (FDA) can detect COVID-19 infection through a breath sample and provide highly accurate results in less than three minutes. Keep reading for answers to commonly asked questions about the most widely used COVID-19 diagnostic tests and why you might opt for one type over another, as well as info about antibody tests that can detect signs of previous infection. RELATED: At-Home Tests for COVID-19: Essential Info The Centers for Disease Control and Prevention (CDC) considers PCR tests the “gold standard” for COVID-19 testing because they are the most sensitive, identifying even tiny amounts of virus. But because PCR tests typically require analysis in a lab, you may need to wait one to three days for results. Antigen tests are a lot faster and can yield results in minutes. But there is a trade-off: As the FDA stated when issuing the first emergency use authorization for an antigen test, in May 2020, “positive results from antigen tests are highly accurate, but there is a higher chance of false negatives, so negative results do not rule out infection.”
How Can You Make an Antigen Test More Reliable?
Taking antigen tests on consecutive days increases the likelihood of an accurate result, says Sajal Tanna, MD, MPH, an infectious disease doctor at Northwestern Medical Group in Chicago. For instance, if you are planning to use antigen tests in advance of a social event, “I would take one about 36 hours before the gathering I wanted to attend, and then do the second test the morning of — to be as cautious as possible,” Dr. Tanna says. These tests are a useful tool, but it’s important to remember that your results are not a guarantee of your COVID-19 status, she adds.
How Is a Specimen Collected for a COVID-19 Test?
There are a few different ways to collect a sample for a COVID-19 test, according to Mayo Clinic. PCR tests most commonly use nasal swabs (either shallow or deep) or a saliva specimen, while antigen tests use a nasal swab to collect a sample. If you have the test at a health department or your healthcare provider’s office, the person administering the test will collect the appropriate sample. For home tests, it’s important to follow the instructions on how to collect the sample. UCLA Health offers an instructional video that shows how to perform a nasal swab.
Do I Need a Prescription to Get a COVID-19 Test? Can I Buy a Home Testing Kit Over the Counter?
If you’re trying to decide if you should take a COVID-19 test and what type you should choose, your healthcare provider can help you make those decisions, according to the FDA. Your doctor can also order a prescription test that can be administered in their office or at home. Nonprescription antigen tests for home use — also called “direct-to-consumer” (DTC) or “over-the-counter” (OTC) — can be purchased online or in pharmacies, supermarkets, and big-box stores such as Target, Costco, or Walmart. These tests are often sold in packs of two, and the cost can vary depending on the store, with a box typically costing around $25, says Tanna. “The at-home tests use the same technology as the tests you’d get at a hospital or doctor’s office,” says Joshua M. Sharfstein, MD, the vice dean for public health practice and community engagement at the Johns Hopkins Bloomberg School of Public Health in Baltimore. If you want to make sure the test you’re buying has been vetted by the FDA, visit the agency website that provides information about which testing kits have been granted emergency use authorization.
What’s an Antibody COVID-19 Test?
An antibody test is altogether different from a diagnostic test, says Dr. Sharfstein. “The antibody test requires a blood test, and the blood serum is examined for the presence of antibodies to indicate that the person was exposed to the virus,” he says. In other words, unlike PCR and antigen tests, which diagnose current infection, antibody tests identify prior COVID-19 infection. Antibody tests can be useful in understanding how the virus is spreading in the general population and identifying groups at higher risk of infection, says the CDC. But they can’t tell you whether you have any natural immunity to COVID-19; whether you need to be vaccinated if you aren’t; or whether you should quarantine after you’ve been exposed to someone with COVID-19, according to the agency.
Is There a Way to Get Tested for Both COVID-19 and the Flu?
It is possible to be infected with COVID-19 and the flu at the same time, according to the CDC. If you are experiencing symptoms that could be either, contact your doctor or local health department for guidance on testing. You can be tested for both viruses at your local health system or health department, and there’s an at-home option as well. Pixel, made by Labcorp, can be ordered online and shipped overnight for an out-of-pocket cost of $169 (check with your insurance company about coverage). According to the company, test results are available one to two days after the lab receives the completed collection kit.
How Can COVID-19 Testing Help With the Pandemic?
In addition to diagnostic testing, screening and surveillance testing are essential for reducing COVID-19 transmission. Screening testing for COVID-19 is useful in many settings, says Peter Mohler, PhD, the chief scientific officer at the Ohio State University in Columbus. This kind of testing is used to identify occurrence of the virus at the individual level even if there’s no reason (such as COVID-19 symptoms or exposure) to suspect infection, according to the CDC. “A good example of COVID-19 screening testing is what’s happening in universities where they are testing their students once or twice a week to see if they are infected as a tool to try to reduce the amount of spread across the campus,” says Dr. Mohler. “Students who test negative can continue to go to class, but a student who tests positive will have to quarantine and may need care,” he says. Surveillance testing is used to look at how the virus is spreading in populations of people, says Mohler. “This might mean you look at the amount of people that are antibody positive for COVID-19 in a city, county, or even a state,” he explains. Surveillance testing may involve sampling a percentage of a specific population to see if COVID-19 cases are rising or declining, or to measure if certain community interventions such as mask wearing or social distancing are working, according to the CDC. “All of these ways of testing are going to be critical tools for us to understand how COVID-19 is or isn’t being contained, and making evidence-based policy decisions,” says Mohler.
If You’re Getting Tested Regularly, Do You Still Need to Be Vaccinated?
It’s important to note that testing is not a substitute for vaccination, nor are the two equivalent in terms of reducing the risk of getting or spreading COVID-19. “Testing is important in order to know what’s going on as best as we can, but knowing alone doesn’t slow down the virus. What slows down the virus is following all the important guidelines for infection control,” Sharfstein says. These guidelines start with being fully vaccinated, masking while indoors in crowded settings or in groups where some people may not be fully vaccinated, and practicing social distancing, according to the CDC.
