Rapid Antigen Test Elucidates High Accuracy In Diagnosing COVID-19

Latest rapid antigen test for COVID-19 – the Abbott BinaxNOW detects positive cases in almost all adults on comparison with a highly accurate positive PCR test (if they had had symptoms lasting seven days or less) as per a study at the Boston Children's Hospital and the Massachusetts Department of Health. The Abbott BinaxNOW test is a nasal swab test that rapidly performs on-site testing. About 85% of true positive cases were picked up in symptomatic children with less than seven days of symptoms.

However, the high amounts of virus in the nose of patients yielded 99% of accuracy irrespective of their age. Thus the test was able to rule out COVID-19 in almost all people who were not infected, including adults and children with and without symptoms.

"What this means is that if the BinaxNOW antigen test comes back with a positive result, that is a reliable true result. For a negative test result, we need to think more carefully about exactly who we are testing and why", says Nira Pollock, MD, Ph.D., associate medical director of the Infectious Diseases Diagnostic Laboratory at Boston Children's Hospital.

The study team enrolled 1,380 adults and 928 children who tested at a large drive-through community testing program run by DPH and Lawrence General Hospital in a highly impacted COVID-19 area. Anterior nasal swab using both BinaxNOW and PCR was done.

Latest Rapid Antigen Test for COVID-19

The BinaxNOW test detected 96.5% of COVID-19 cases similar to PCR, in adults who had symptoms lasting seven days or less whereas, in children, 84.6% of cases were detected (~12 percent difference). Symptomatic adults tended to have high viral loads so they were almost all detected by the BinaxNOW test. Hence the viral load impacted the difference in testing results.

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The test kit detected 70% of asymptomatic adult cases as compared with 65.4% in asymptomatic children. The team also proved no user-dependent differences in interpretation of the BinaxNOW test.

"That suggests to me that you do not need more than one person to do the test. That's good to know in cases where this test may be used in a school nurse's office or another site where there is only one person available to do the testing. Given the difference we saw between symptomatic adults and children, we need to think carefully about what to do in children who have a negative rapid test, and whether it might sometimes be necessary to supplement that rapid test with PCR testing. The same is true for potential use in asymptomatic adults and children where the detection rates are even lower. Public health officials need to thoughtfully consider the prevalence of COVID-19 in a community and the specific goals of a community's testing program when deciding how to use this rapid test," says, Pollock.

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The study affirms the use of the BinaxNOW test in adults and children with symptoms of seven days or less without recommending a PCR confirmatory test. However it is not recommended for use in adults or children with symptoms lasting longer than seven days.

Source-Medindia