The rise of highly-spread delta variants across the United States has increased the demand for rapid antigen COVID-19 tests, which can be purchased from pharmacies without a prescription, used at home, school, or workplace, and given within 15 minutes The results.
On September 9, 2021, the White House announced several measures to improve the accessibility of rapid antigen testing: it will use the National Defense Production Act to promote the production of tests, requiring retailers to sell rapid tests at cost and distribute them to the community for free Rapid testing of health centers and food banks, and expansion of free testing in pharmacies.
Rapid antigen testing makes it easier to detect COVID-19, which helps to detect infectious cases before they spread. But many people are still not sure how to best use these tests and whether they are accurate enough for use.
There are several FDA-approved rapid tests on the market, including Abbott BinaxNow, Ellume, and Quidel QuickVue. These costs are as low as $7-12 each and can be used to test adults and children 2 years and older, regardless of whether they have symptoms.
In terms of speed and convenience, rapid antigen detection has great advantages over laboratory-based PCR detection. Getting results in 15 minutes, instead of waiting a day or longer for PCR test results, means that COVID-19 cases can be immediately identified and preventive measures can be taken to prevent spread. Having fast over-the-counter testing means that more people will be tested because it is easy to perform and much more convenient than PCR testing. Therefore, compared to relying solely on PCR testing, rapid testing can capture more COVID-19 cases overall.
as a Health economist Whoever studies public health policies to combat the epidemic of infectious diseases, I know that making COVID-19 testing easy, accurate, and fast is essential to slow the spread of the virus and help everyone resume normal activities safely.
How accurate is the rapid antigen test?
There are two types of rapid tests that can be used to detect active COVID-19 infection: rapid antigen tests that use paper strips to detect viral proteins and rapid molecular tests (including PCR) that use medical equipment to detect viral genetic material.
It is important to remember that rapid antigen testing has a different purpose than PCR testing, and PCR testing is considered the gold standard, even if it is not 100% accurate. The rapid test is designed to identify cases where the viral load in the nasal passages is high enough for transmission, not to diagnose all COVID-19 cases. The Abbott BinaxNOW rapid antigen test may only detect 85% of cases with a positive PCR test. But the key is that published studies found that they found more than 93% of cases that pose a risk of transmission, which is the most important for controlling the pandemic. Ellume correctly identified 95% of all positive cases, and Quidel QuickVue correctly identified 85%. Regardless of the symptoms, all three tests correctly identify more than 97% of all negative cases.
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How should the rapid test be used?
There are three ways to use rapid antigen testing to slow the spread. First, people can take a quick test when they have suspected or known exposure to COVID-19. Second, rapid testing can provide additional precautions before any activities with a higher risk of transmission (such as parties or travel). Third, tests can also be performed regularly—for example, once a week if enough tests are available—to find cases that might otherwise be undetectable.
It is very important to make a plan based on the test results. If you get a positive result, take preventive measures immediately to slow the spread, such as self-isolation, let close contacts know the test results, and report the case to the health authorities. Fewer than 3% of negative cases will have false positives, but if needed, a second rapid test or PCR test the next day can provide further confirmation.
If you get a negative result from the rapid test, it means that you are currently unlikely to be infectious. The viral load is too low to be detected by a rapid antigen test, and it is almost certainly too low to spread. But the important thing is not to let your guard down completely. These tests cannot detect 100% of infectious cases, so a small number of cases may avoid testing, or some cases may become infectious within hours of testing. Therefore, it may be a good idea to maintain other precautions. Moreover, if you have symptoms or known exposure, it is best to perform a follow-up rapid antigen or PCR test to prevent false negatives on the first test.
Think of a rapid antigen test as a timely snapshot: a negative test does not necessarily mean that you are not infected with COVID-19. COVID-19 spreads most easily when the viral load reaches its peak, which is estimated to be within a week after infection. Those who are infected but undergo a rapid test before or after the peak viral load will get a negative rapid test result-which means that even if they are infected, they are not currently infectious. One way to reduce the risk of false negatives is “continuous testing”, which means a second rapid test is performed 24-36 hours later to help find any cases of infection that were missed in the first test.
Are the new measures sufficient?
The White House’s move to increase rapid testing opportunities is a key step in curbing the number of cases. But one free test per person is not enough to help people resume normal activities safely. Additional cheap rapid tests authorized by the Food and Drug Administration will further expand supply and lower prices.
Making the COVID-19 vaccine free and easy to obtain will rapidly reduce the number of cases in the spring of 2021. It is now possible to make frequent and rapid tests available to everyone.
This article has been corrected to clarify that less than 3% of negative cases received false positives.
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