PCR stands for polymerase chain reaction. It is a type of test used to detect genetic material from the virus that causes COVID-19 in a sample from an upper respiratory tract (nose or throat) specimen or saliva. PCR tests are very accurate when performed properly, but there are still some limitations with this method of testing.
PCR stands for polymerase chain reaction. It is a test used to detect genetic material from the virus that causes COVID-19 in a sample from an upper respiratory tract (nose or throat) specimen or saliva.
PCR tests are very accurate when performed properly.
PCR stands for polymerase chain reaction. PCR is a type of test used to detect genetic material from the virus that causes COVID-19 in a sample from an upper respiratory tract (nose or throat) specimen or saliva.
In this test, your doctor will use a swab of mucus from the inside of your nose or mouth to collect DNA from any viruses present there and send it to a lab for processing. The results generally take about two days; if no infection is found, you'll be notified within 24 hours.
PCR tests are very accurate when performed properly. However, it is important to note that PCR tests are not 100% accurate and can result in false positives. The reason for this is the specificity of the test. While PCR tests are highly sensitive (meaning they will detect very small amounts of target DNA), they aren’t 100% specific (meaning they may detect other things that aren’t targets). For example, if you were performing a PCR on a sample containing avian influenza virus and human adenovirus 2 (humans carry both viruses), your test could still show positive for avian influenza even though it isn't present in your sample because your test was also able to detect human adenovirus 2 as well.
A positive PCR test does not necessarily mean that you have a current infection because the test can pick up genetic material even after you no longer have active infection and do not have symptoms. It is possible for someone who has been infected with the virus to test negative on their first PCR test but later develop symptoms.
In addition, the accuracy of an individual's final diagnosis depends on how high or low the level of mRNA in their blood sample is relative to what is considered normal for them. The normal range varies among laboratories and countries due to differences in how standard procedures are performed, so it's important to be aware that your results may differ from those obtained elsewhere.
A negative PCR test means that, if you have COVID-19, there was no virus in the sample to detect. This may be because you don't have an active infection or because the test missed it. PCR is not perfect and can sometimes miss a few cases of COVID-19.
A negative result does not mean that you are definitely not infected with COVID-19; it only means that whatever was tested for was not found in your blood at that time period. If you are worried about being tested positive for COVID-19, then talk to your doctor about getting tested again later on in your illness when they can determine whether or not they think it's likely that there might be more virus present in your system by then.
There is still more research to be done on PCR testing.
There are some limitations with the test, including false positives and false negatives.
For example, a person may be diagnosed with Ebola when they actually don't have it. This could happen if their symptoms aren't consistent with those of an Ebola patient or if their PCR test came back negative even though they do have the virus. In these cases, other tests would be needed to confirm diagnosis—like ELISA or cell culture tests (see below).
On the other hand, someone who does have Ebola might not have a positive result on their PCR test because they're currently being treated by another method (such as IV fluids). This is why it's important to know that PCR results are only accurate when used in conjunction with other diagnostic methods like ELISA and cell culture tests (described below).
PCR testing is a good way to find out if you have COVID-19 and can help your doctor decide if they need to prescribe antiviral medications. But as we've seen, there are some limitations. The test is less likely to be accurate in people who are immunocompromised or have been taking steroids (like prednisone), so make sure your doctor knows if this applies before they send you off for PCR testing. Also keep in mind that a negative result doesn't mean that there's no virus present—it may just mean that the test missed it!