Rapid coronavirus tests can best detect antibodies in a person's bloodstream 14–50 days after first Covid-19 symptoms appear, but are of little use for diagnosing the virus, Vilnius University researchers say.
To evaluate the reliability of rapid Covid-19 tests, researchers at Vilnius University and its hospital, Santara Clinics, the university's hospital, have serological test kits made by three different producers. The tests can detect the presence of IgM, IgG or IgA antibodies in one's bloodstream.
“Serological tests are not suitable for diagnosing acute infection. They can be suitable for confirming a late infection or a previous one,” Vilnius University said in a press release.
There are yet no uniform recommendations for the use of serological tests. Individual countries issue their own recommendations after assessing the reliability of these tests, the Lithuanian researchers noted.
Rapid tests are simple and can give results in a matter of minutes, making them extremely convenient for mass testing. However, most rapid serological tests available on the market have not undergone proper validation procedures and their reliability must be assessed before they can be used, according to the press release.