Rapid antigen test detects SARS-CoV-2 even in asymptomatic people
The study, in which IrsiCaixa has participated, shows that the rapid antigen test is particularly effective in samples with high viral loads, which are the ones associated with high transmissibility
The rapid antigen test, Panbio COVID-19 Ag-RDT, is highly effective in detecting the presence of SARS-CoV-2 virus in both symptomatic and asymptomatic people. This is confirmed by a study led by the researcher at the Fight AIDS and Infectious Diseases Foundation, Oriol Mitjà, which counts on the participation of IrsiCaixa researchers and funding from the #YoMeCorono initiative. The discovery highlights the potential of antigen tests to control the transmission of the virus, since they can detect which people are contagious and stop the spread of the virus with great reliability.
The study evaluated the clinical and analytical performance of the Abbott trademark rapid test and compared the results with the standard PCR tests. At the moment, PCR has obvious drawbacks as an epidemiological control tool, including the need for a laboratory, its high economic cost and the long time between sample collection and processing of the results.
A sensitivity and specificity higher than 90% in symptomatic people
During the trial, researchers have processed nearly 1,500 frozen nasopharyngeal samples, which had previously been PCR tested. After comparing the results obtained from the PCR and the antigen test, it can be confirmed that the sensitivity of the rapid tests, that is, the ability to detect positive cases, is higher in symptomatic individuals (92.6%) and their contacts (94.2%), and lower among asymptomatic individuals (79.5%). In addition, rapid tests have shown a specificity –the ability to detect negative cases– of 98.9%. As for the waiting time for results, which in the case of a PCR test can take up to hours, in the case of the rapid tests evaluated it is reduced to 15 minutes. According to Oriol Mitjà, "the results of this study allow us to affirm that the rapid tests are useful tools for checking the presence of the virus in the population and, therefore, can be used to reduce the transmission of the COVID-19 in the community. In addition, they have important advantages such as their lower price and ease of use".