From November 2021, self-tests detect current coronavirus infections, not antibodies to the virus, according to the CDC.
Everyone should have at least two home tests for each family member, said CNN Medical Analyst Dr. Leana Wen, an emergency physician and visiting professor of health policy and management at the George Washington University Milken Institute School of Public Health.
“If you have symptoms or have been significantly exposed to someone with Covid-1[ads1]9, you should take a PCR test. It is the gold standard,” said Wen. “Home antigen tests should ideally be used when you are asymptomatic and the likelihood of having Covid is quite low, but you are using it for insurance purposes.”
“Think of the rapid test at home as a screening test … for public health purposes, not a diagnostic test,” Wen added.
Consider using a self-test before joining indoor gatherings with people who do not live with you, the CDC recommends. This suggestion is especially important if you plan to be around unvaccinated children, older adults, immunocompromised people or those at risk of serious illness – and of course if you have Covid-19 symptoms or have been exposed to or possibly exposed to someone with Covid-19.
Here is what else is important to know before, during and after a self-test.
Prepare and take self-tests
Until you are ready to use the test, store all test items according to the manufacturer’s instructions, says the CDC. This does not include opening it until you are ready to use it.
Before taking the test, clean the surface – such as the worktop, table, etc. – on which you are going to perform the test. Have a timer ready as you may need to schedule some of the steps.
Carefully read all the manufacturer’s instructions, the CDC recommends. Then wash your hands with soap and water for at least 20 seconds. When opening the box, check the test for damage or discoloration according to the manufacturer’s description.
To collect the nasal or saliva sample – depending on the type of test you have – and complete the test, follow the included instructions chronologically.
Read the test results only within the time frame specified in the instructions, says the CDC. If you do not follow the instructions, the test results may be incorrect or invalid or say “incorrect”. If this happens – due to incorrect use or test error – check the package leaflet for information or contact the manufacturer for assistance.
Once you have taken the test, do not reuse any of the items, says the CDC. Throw them in the trash, clean any surfaces the sample may have touched and wash your hands.
If you test positive, isolate yourself for at least 10 days and tell your doctor and all people you have recently had contact with. Avoid indoor gatherings, and wear a mask if you live with others.
If the result was negative and you are asymptomatic, you may not have an infection – but that possibility is not ruled out. Doing “serial tests” can make self-testing more reliable and reduce the risk of coronavirus spread if you are infected, according to the CDC. This means doing two or more tests over several days with at least 24 hours between tests, with one test as close as possible to the event you want to attend.
However, if you have Covid-19 symptoms but still test negative, “you should just go straight to a PCR test. Why take a home test?” in Wen. “The only situation where you would do that is if you just do not have access to a PCR test.”