The message is clear: Get tested, as it’s one of our best defenses against stopping the spread of COVID-19. What’s not so clear is which kind of COVID-19 test is the best.
Types of COVID-19 tests
Two types ofCOVID-19 testsare popular: thepolymerase chain reaction (PCR) test and the antigen test也就是快速测试。两种检测都需要患者的样本，通常是鼻拭子。
PCR test
How it works
The PCR test takes a sample of ribonucleic acid (RNA) and “amplifies” it with the help of lab technologies. Amplifying RNA helps to make even small traces of the COVID-19 virus visible in the test sample. Even if you have a small trace of the virus in your system, the PCR test will detect it.
The PCR test doesn’t alter your genetic material – DNA – in any way, and your test provider isn’t able to do anything with your DNA besides tell if you’re positive with COVID-19.
Benefits
“PCR tests are more reliable and accurate due to testing the specific genetic material of the virus, eliminating the interference from other viruses,” said Heather Seyko, a Laboratory Services manager for OSF HealthCare.
Drawbacks
While a PCR test is the preferred method of detecting COVID-19, it’s not always the easiest test to get. PCR tests must be done by a health care provider, and they don’t produce immediate results, which means you may be waiting a few days to know if you’re positive or negative.
TheCenters for Disease Control and Preventionnotes while tests are best used early in the course of illness to diagnose COVID-19, they are not authorized to evaluate the duration of infectiousness. PCR tests can stay positive for weeks sometimes after you’ve had COVID. This is because the PCR test is so sensitive it can detect even dead virus.
Antigen test
How it works
The rapid test, called an antigen test, checks for proteins that are found on the outside of the virus.
The antigen test mimics what antibodies do.Antibodiesare the “good guys” that attach to the antigen protein (the “bad guys”) and fight the virus. When you give your nasal swab sample, it’s put into a liquid and then onto a test strip.
这种试纸的作用就像一种抗体——如果你的系统中有任何COVID-19抗原“坏人”，液体中的分子就会附着在这些抗原上，一条线就会出现在试纸上。这意味着你感染了COVID-19。如果你的身体系统中没有检测到抗原，这种液体就不会有反应，也不会出现细胞系，这通常意味着你的病毒检测呈阴性。
Benefits
- Results in about 15 minutes
- Easy enough to do on your own (There’s always a little room for user error, but as long as you closely follow the directions, anyone can test themselves with an antigen test.)
- Helps slow thespread of contagious viruseslike COVID-19 with quicker results
Drawbacks
“与PCR检测不同，抗原检测只能确定你体内是否有活性病毒。这种快速检测不能像PCR检测那样准确地检测出少量的病毒或无症状病例。”
快速检测的准确性较低，出现假阴性的可能性较大。此外，这种检测只会检测出病毒在你体内活跃的情况，这意味着无症状病例——即某人没有任何症状——更难通过抗原检测识别。
Choosing which test to get
Experiencing symptoms?
If you’re visiting a health care provider to get tested, it’s likely you won’t get to choose which test you get. This is for a few reasons. First, it could just be a matter of what test is readily available or in greater supply. Second, tests are chosen based on probability of having the virus.
“PCR would be chosen where there is a low likelihood of having the virus, but we want to be certain the patient doesn’t have it. Antigen would be chosen if there is a high probability the patient has the virus (i.e. isexperiencing symptoms), and we need to screen the patient as positive or negative,” Heather said.
Getting tested is an important part ofslowing the spread of COVID-19. With more accurate results, PCR tests are the preferred way to go, but antigen tests work for rapid results, as well.