As of March 7, 2021 over 3 million COVID-19 tests were taken in the United States alone, and that number is likely even higher today. With the virus’s many variants still circling the globe, demand for quick and accurate tests is high. The antigen test for Covid19 allows for rapid testing and is in demand, especially the at-home test kits that can give you a result in a matter of minutes. But there is still a prominent question that lingers: “How accurate is a Covid-19 antigen test?” Although results may be given quickly, studies have shown that false negatives happen more often with antigen tests than with PCR tests.
Let’s discuss the Covid antigen test accuracy rate, along with what the test is and how it is done.
An antigen test looks for specific proteins that are on the COVID-19 virus’s surface. The results for antigen tests can be received quickly, with most results seen within 15-30 minutes. This is significantly less wait time than the PCR test, which typically take 24 hours or more to receive a result. Since antigen tests are rapid and inexpensive, they are likely used for individuals who want to test at home or in high outbreak areas to quarantine those with positive test results quickly. However, antigen tests have a high result of false-negatives—meaning that an individual that is infected with the virus has the potential to still test negative.
So, exactly how is an antigen test done? An antigen test is taken using a long nasal swab up an individual’s nose to get a fluid sample to test for the COVID-19 protein. This is similar to the PCR test that also uses a nasal swab, although instead of looking for a protein, the PCR test detects the genetic material of the virus. Saliva tests are also PCR tests, not antigen tests.
According to a study by the CDC, 1 in 5 individuals with symptoms and a confirmed case of COVID-19 received a negative result from the antigen test. In another study by Cochrane, the antigen test correctly identified COVID-19 infections in only 72% of individuals with symptoms and 58% of people without symptoms. In individuals who did not have COVID-19, the antigen test correctly ruled out 95% of individuals with symptoms and 98.9% of people without symptoms. According to this study, the tests were most accurate when the individual was tested one week after symptoms first developed.
As seen in the research above, the COVID-19 antigen tests are known to be fast and inexpensive, but are more likely to give false-negatives. Antigen tests have to be carried out with very specific instructions. A positive test is only considered accurate if the instructions were specifically followed. It has been known that the antigen test produces more false-negatives than the PCR test due to the possibility of the test not being taken correctly.
The PCR tests are still considered the gold standard because they require a trained health professional at every step of the process. Under certain circumstances, a doctor may recommend a PCR test to confirm a negative antigen test. According to a study by Annals of Internal Medicine, cited by the Harvard Health Publishing, the false-negative rate was only 20% for the PCR test.
Have you been exposed to COVID-19 and are looking for a quick way to get tested? Although Googling “rapid antigen test for Covid19” might bring up search results for quick COVID-19 tests, the result of getting a false-negative is likely, leaving you to still wonder about your infection status.
At Biocollections Worldwide, we test confidently. We offer PCR nasal swab tests with results in about 20 hours, no appointment required. With over 20 years of experience, we are a leader in diagnostics and testing—keeping up to date with developments and testing so we can provide you with the most accurate results possible.