a cheap antibody test reveals if you are immune in 5 minutes

Researchers at Hong Kong Polytechnic University have designed a sensor that can detect SARS-CoV-2 antibodies in just 5 minutes. Inexpensive and portable, the device shows great promise for the rapid assessment of prognosis in the event of COVID-19 later. By analyzing saliva or blood, it not only allows you to quickly know if a person has contracted the coronavirus in the past, but also to assess the level of antibodies (and therefore likely immunity) generated by the infection or the vaccination.

When a person is infected with the coronavirus or is vaccinated against it, their immune system produces specific antibodies that can fight the virus in the event of subsequent infection. These antibodies continue to be produced for at least six months, so they can be used to detect a past infection or vaccine response. Of course, there are already many rapid tests for antibodies, but they are usually expensive, complex, or imprecise.

Feng Yan of Hong Kong Polytechnic University and his colleagues have developed a cheaper and more convenient anti-COVID-19 antibody test using organic electrochemical transistors. These, which are increasingly used to detect biological molecules such as proteins and glucose, convert biological signals into electrical signals.

A result in 5 minutes flat

To perform the rapid test, a drop of blood or saliva is placed on one of these gold transistors, embedded in a small strip of plastic. When antibodies to the coronavirus attach 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.

Diagram of portable detection system and IgG sensor modification processes. The device is connected to a portable meter which is controlled by a mobile phone via Bluetooth. © Feng Yan et al.

The test was found to be very accurate in measuring anti-coronavirus antibodies when tested on blood and saliva samples that had been spiked in the lab with different levels of antibodies, including very low levels. Yan and his colleagues are now planning a clinical trial to confirm that the test also works in real situations. ” If the trial is successful, the team will seek approval to market the test, which is expected to cost less than a dollar per strip. », Says Yan.

Like other anti-COVID antibody tests, the new test could be useful in estimating levels of immunity to the virus – whether from natural infection or from vaccination – in different populations. It could also indicate when the protective effects of the vaccines start to wear off and boosters are needed, Yan adds.

However, the device cannot be used to determine whether a person has just been infected, as it usually takes a week or two after contracting the virus for significant levels of antibodies to be produced. ” These wearable sensors show promise for use in the diagnosis and prognosis of COVID-19 », Conclude the researchers in their document.

Source : Science Advances

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