As the government announced yesterday that everyone in Macau must undergo rapid antigen tests (RATs – self-tests) today and tomorrow, an expert told The Macau Post Daily in an online interview yesterday that false results could occur if the self-test is not done correctly.
Dr Cheong Io Hong from the Public Health School at Shanghai Jiao Tong University, who specialises in infectious diseases, spoke about the “false negatives” and “false positives” for RATs.
Cheong noted that using the self-test kits incorrectly can easily lead to ‘false positive’ results, with the most common errors being entering the sample into the wrong place in the test equipment other than the sample well, degradation or too little of the buffer solution in the sample, which leads to insufficient liquid to take the test, and the misoperation of swabs.
Cheong cited the research by a group headed by Thirumalaisamy P. Velavan, who is from the University of Tübingen in Germany, as an example, which shows that various soft drinks, energy drinks and alcoholic beverages, such as Coca Cola Light, Red Bull, vodka, whiskey, could activate a rapid antigen test’s positive reading.
However, positive test lines do not occur when an equal volume of the buffer solution and the respective beverages are mixed, Cheong said, pointing out that the test is strongly affected by pH and other physical parameters.
As such, Cheong said, a RAT kit is more a “self-disciplinary” tool, and he urged people to follow the instructions in the kit before the self-test in order to conduct it correctly, so that false results could be avoided as much as possible.
Further information on procedures, the test result declaration and usage notes can be found at https://www.ssm.gov.mo/apps1/covidagtest/ch.aspx#clg2198, while RAT results must be declared at https://app.ssm.gov.mo/generalrat/, which can also be found on the bottom of the Macau Health Code’s home page.
This undated photo shows an RAT self-test kit. – Courtesy of Heho
