CategoryTesting

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.

https://www.newscientist.com/article/2290120-cheap-covid-19-antibody-test-shows-if-you-have-immunity-in-5-minutes/

A simple blood test could help predict which people with covid-19 are likely to get severely ill and need to go on a ventilator. The test measures levels of antibodies in the blood that are directed against molecules released by dead blood cells, including their own DNA.

The test may also prove helpful in infected people before they reach the stage of needing hospital treatment, says Ana Rodriguez at NYU Langone in New York. It is likely to be less accurate in that group, but it could indicate who needs closer monitoring, she says.

People who get severely ill from covid-19 tend to deteriorate at least a week or more after symptoms begin, when virus levels are falling, suggesting it is something about the person’s reaction to the infection that causes their problems, rather than the virus itself.

Rodriguez’s team looked at blood tests done on 115 people admitted to hospital with covid-19 in 2020. About half of these people became severely ill and needed oxygen support, while the rest recovered quickly.

Those with high levels of antibodies directed against DNA or a fatty molecule from cell membranes called phosphatidylserine had about a 90 per cent chance of deteriorating. But the test only identified about a quarter of people who got worse. “It won’t mean we catch everybody but if you have this, it looks very bad,” says Rodriguez.

It is unclear if the antibodies detected by the test are involved in the person’s deterioration, or if they are innocent bystanders.

https://www.newscientist.com/article/2289718-blood-test-could-reveal-who-is-most-likely-to-get-severe-covid-19/

Rapid lateral flow tests are 95% effective at detecting coronavirus if they are used at the onset of infection or as soon as symptoms start, a new study suggests.

Scientists have previously said that lateral flow tests (LFTs) are less sensitive at picking up COVID-19 cases than laboratory tested PCR swabs.

But a study of more than 2,500 people with flu-like symptoms has shown that LFTs picked up 95% of the coronavirus cases that the PCR tests did.

It also correctly identified 89% of COVID cases as negative.

LFTs function like pregnancy tests and look for coronavirus proteins to detect cases and take just 30 minutes.

PCR (Polymerase Chain Reaction) tests are laboratory tested and can take up to three days to process.

The research, carried out by experts at Queen Mary University of London, Oxford University, the Institute for Advanced Studies in Vienna and the Medical University of Graz, is the first to compare the two forms of testing on a group of this scale.

https://news.sky.com/story/covid-19-rapid-lateral-flow-tests-95-effective-at-detecting-covid-if-used-when-symptoms-start-study-shows-12355179