What are the different types of at-home tests?
So far, the FDA has given what’s called emergency use authorization (EUA) to five at-home tests. That means the tests haven’t gone through the full rigorous FDA approval process, but the agency wanted to get them on the market quickly due to the severity of the pandemic. The tests are:
- Ellume’s COVID-19 Home Test: This was the first at-home test to be authorized that can be done without a prescription. It uses so-called antigen technology, meaning it looks for fragments of viral proteins. On Feb. 1, the federal government announced a $231.8 million deal to boost manufacturing of the test. The company is working with retailers to get the test on store shelves, a spokeswoman said, and it will also be sold online. It will cost about $30. The test delivers your results wirelessly to a smartphone app in 15 to 20 minutes.
- Where/when to find it: Sold over the counter at pharmacies and retail stores. Distribution is expected to start this spring.
- Type of test: Antigen
- Does it require a prescription? No
- Cost: About $30
- Who can use it: People with or without coronavirus symptoms as young as 2 years old
- How long to get results: 15-20 minutes, delivered via a smartphone app
- You need to know: Results are more likely to be accurate if you have symptoms.
- Abbott’s BinaxNOW COVID-19 Antigen Self Test: This rapid antigen test has been used for months by health care providers, but on March 31, the FDA authorized it to be sold over the counter and used at home, even by those who have no symptoms. The test will be sold in packs of two, and the instructions call for it to be administered twice over three days. Repeat testing helps reduce the chance of inaccurate results. In a March 31 press release, Abbott said the test will be available “in coming weeks” on drugstore and grocery store shelves. Results are delivered in about 15 minutes on a device the size of a credit card.
- Where/when to find it: Sold over the counter at pharmacies and retail stores. Distribution is expected to start in spring or summer.
- Type of test: Antigen
- Does it require a prescription? No
- Cost: The company hasn’t announced a price, but said in a press release it will be “priced affordably — similar to other OTC tests.”
- Who can use it: People with or without coronavirus symptoms as young as 2 years old.
- How long to get results: After 15 minutes, delivered on a small plastic card that has either one or two lines
- You need to know: Results are more likely to be accurate if you have symptoms; To increase accuracy, the instructions call for users to administer two tests over three days, at least 36 hours apart.
- Quidel’s QuickVue At-Home OTC COVID-19 Test: This is another antigen test that will be sold over the counter. Like the one from Abbott, it will be sold in packs of two, and the instructions call for users to test themselves twice over two or three days, with at least 24 hours between tests. Results are delivered on a paper test strip that changes color in 10 minutes, similar to a home pregnancy test.
- Where/when to find it: Sold over the counter at pharmacies and retail stores. The company has not announced a distribution timeline.
- Type of test: Antigen
- Does it require a prescription? No
- Cost: The company hasn’t announced a price.
- Who can use it: People with or without coronavirus symptoms as young as 2 years old.
- How long to get results: 15 minutes, delivered on a paper test strip that changes color
- You need to know: Results are more likely to be accurate if you have symptoms. To increase accuracy, the instructions call for users to administer two tests over two or three days, with 24 to 36 hours between the tests.
- Cue’s COVID-19 Test for Home and Over the Counter Use: This test is also authorized to be sold over the counter without a prescription, but it uses molecular technology, which can pick up very small amounts of genetic material. Molecular tests are generally more accurate than those that use antigen technology, especially in patients who are asymptomatic. Results are available in about 20 minutes. Cue Health cofounder and chief product officer Clint Sever said the company is working to make the test available at retailers nationwide, but he did not have a time frame. The company has yet to set a price for the test.
- Where/when to find it: The company is working to get it into pharmacies and retail stores. No timeline has been announced.
- Type of test: Molecular
- Does it require a prescription? No
- Cost: Has not yet been set
- Who can use it: People with or without coronavirus symptoms as young as 2 years old.
- How long to get results: About 20 minutes, delivered via a smartphone app
- You need to know: The only molecular test authorized to be used without a prescription. Because molecular tests can detect very low levels of the virus, they are generally more accurate than antigen tests, especially if you are asymptomatic.
- Lucira’s COVID-19 All-In-One Test Kit: Like the Cue test, the Lucira one uses molecular technology. It is priced at $50, and you need a prescription to use it. Lucira is selling the test directly to health care providers; a spokesman says your doctor can order it for you. It takes about 30 minutes to deliver results.
- Where/when to find it: Lucira is already selling the test to U.S. physicians; your doctor can order it for you.
- Type of test: Molecular
- Does it require a prescription? Yes. The test must be prescribed by a health care provider.
- Cost: $50
- Who can use it: People age 14 and older suspected by their health care provider to be infected with the virus
- How long to get results: 30 minutes or less
- You need to know: Like the Cue test, it uses molecular technology, which is considered more accurate because it can pick up lower levels of the virus than antigen technology.
How accurate are the tests?
Data submitted to the FDA for all of the four tests shows high accuracy rates – above 80 percent — but testing experts noted that their effectiveness in the real world will likely be lower due to user error and other factors.
Studies show antigen tests miss many asymptomatic infections. They work best when you’re having COVID-19 symptoms, Wroblewski said. Common signs of COVID include cough, fever, fatigue, muscle aches, congestion, runny nose, loss of taste or smell, nausea, vomiting and diarrhea, according to the U.S. Centers for Disease Control and Prevention (CDC).
The Ellume, Abbott BinaxNOW and Quidel QuickVue tests use the same antigen technology as many of the rapid tests given by health care providers. Antigen tests are less accurate than the gold standard method used by labs called polymerase chain reaction, or PCR.
The Cue and Lucira tests use a newer molecular technology called isothermal amplification that is similar to PCR. Like PCR, it works by copying the virus’s genetic material until there are detectable levels.
David Pride, M.D., director of the clinical molecular microbiology laboratory at the University of California, San Diego, says that while molecular tests are generally more accurate than antigen tests because they can detect the virus at lower levels, they are still less sensitive and less specific than a PCR test done in a lab.
For any at-home test, if you have symptoms and you test positive, “it’s very, very likely you have the virus,” Pride said, and you should go into isolation and get in touch with your health care provider.
How confident can you be of a negative result?
A negative test can give you more confidence about going into work or visiting a family member, but experts emphasized that it’s not a free pass to stop wearing a mask, practicing social distancing or taking other precautions.
“The danger is that you’ll have people use these tests to say I can safely go see grandma, when they may be brewing an infection that is below the limit of detection,” said Gary Procop, M.D., medical director in clinical virology at the Cleveland Clinic. “People really need to understand these subtleties, and they’re not all on the package insert,” he added.
Antigen tests, in particular, are likely to miss the virus if you’re early in the infection or if you don’t have symptoms.
A study published by the CDC on Jan. 22 found that Abbott’s antigen test identified only 34 percent of COVID-19 infections in people without symptoms.
A large-scale review of 68 studies published March 24 found that rapid antigen tests identify about 72 percent of people with symptoms and only 58 percent of those without symptoms. Antigen tests are most accurate when used within the first week after symptoms develop, the review found.
The FDA-authorized instructions for use for antigen tests stress that “negative results do not rule out COVID-19 and should not be used as the sole basis for treatment or patient management decisions, including infection control decisions.”
If you test negative but have symptoms, reach out to your health care provider, because there’s a high risk it’s a false negative, Procop said. Your doctor may order a PCR test to confirm your result.
How difficult is it to give yourself a test?
The authorized at-home tests all require you to collect a sample by swabbing your nostrils, either just inside or a little deeper, depending on the test. The good news: You don’t have to insert a swab into the deepest part of your nose like some of the tests performed by health care providers.
As a general rule of thumb, “make sure you’re really swirling it around and hitting skin,” Wroblewski advised. Also, avoid blowing your nose right before you take the test.
All of the tests include detailed instructions with pictures.
When is it better to get the test from a health care provider?
If your symptoms are severe or if you are in a group at high risk of complications from COVID-19, some experts recommend getting tested by a health care provider rather than doing an at-home test.
“With COVID, your oxygen saturation counts can decrease pretty quickly, particularly if you are in a high-risk group, so you want to make sure someone is monitoring your condition,” Wroblewski said.
