A cheap 5-minute test can accurately determine whether you have had covid-19 in the past or determine whether you have protection from a vaccine by detecting antibodies in blood or saliva.
When a person is infected with the coronavirus or is vaccinated against it, their immune system produces antibodies to fight the virus. These antibodies continue to be produced for at least six months, so they can be used to detect a past infection or vaccine response. Tests for coronavirus antibodies already exist, but they tend to be expensive, complicated or not very accurate.
Feng Yan at the Hong Kong Polytechnic University and his colleagues made a cheaper, more convenient covid-19 antibody test using organic electrochemical transistors. These convert biological signals to electrical signals, and are becoming popular for detecting biological molecules like proteins and glucose.
A drop of blood or saliva is placed on one of these transistors, which is made of gold and embedded in a small plastic strip. As coronavirus antibodies bind to it, the transistor produces electrical signals that are read by a lightweight portable meter connected via Bluetooth to a mobile phone. The whole process takes less than 5 minutes.
The test proved to be highly accurate at measuring coronavirus antibodies when it was tried on samples of blood and saliva that had been spiked with different antibody levels in the lab, including very low levels.
Yan and his colleagues are now planning a clinical trial to confirm the test also works in real-world settings. If the trial is successful, the team will apply for approval to sell the test, which should cost less than $1 per test strip, says Yan.