Accurate and widely available testing is essential to curbing the COVID-19 pandemic, especially in light of the recent escalation in cases due to the Delta variant and other possible mutations. However, there is widespread confusion about the differences between the testing options currently available to consumers and clinics.
There are currently two basic types of diagnostic tests that can detect whether a person has been infected with the SARS-CoV-2, the virus that causes COVID-19, rapid antigen tests and PCR (polymerase chain reaction) tests.
The antigen test (also known as a rapid test) works by detecting protein fragments called antigens that are specific to the SARS-CoV-2 virus. These tests are frequently used in doctor’s offices, clinics, and even at home. Results are received quickly, sometimes in as few as 15 minutes.
However, antigen tests can be problematic since they are less accurate than PCR tests – because a higher level of the SARS-CoV-2 virus is needed in the sample to be identified as positive, there is more room for error.
Often infected people who are asymptomatic (these cases make up to 40% of people who are contagious) or who have just been infected are falsely reported as negative. In fact, antigen tests have shown false negative rates of up to 50%.
The more reliable diagnostic testing method is PCR testing, which detects actual genetic material (RNA) specific to SARS-CoV-2, the virus that causes COVID-19.
This molecular test is performed in a laboratory using a technique known as Polymerase Chain Reaction (PCR), which works by rapidly making millions to billions of copies of viral-related DNA. If there are even a few copies of this genetic material in the sample, it will be flagged as a positive result.
Because of this sophistication, PCR test results are often far more reliable than antigen tests. In fact, a positive test identified by PCR testing is almost never wrong. Unlike antigen tests, PCR tests can reliably detect the virus within days of infection, even in those who have no symptoms.
This high rate of accuracy is why PCR tests are often required by many schools, businesses, airlines, and other organizations to prove that someone is indeed COVID-free.
In addition to regular testing, both individuals and groups can help stop the spread of COVID-19 by adhering to the CDC guidelines found at https://www.cdc.gov/coronavirus/2019-ncov/index.html.