Finger prick test shows who is at risk of Covid reinfection

A FINGER-PRICK blood test that can identify people most at risk of being reinfected with Covid-19 could help tailor the booster programme to those who need it most.

Scientists at Cardiff University and biotech firm Immunoserv have developed a test that measures the presence of immune T-cells that recognise Covid19, and mount an immune response.

Trials on 300 volunteers showed that individuals with the best T-cell response were less likely to pick up an infection in the following three months, regardless of their levels of antibodies.

Researchers say the tests will help determine who might need booster vaccinations, or could skip a jab.

Dr Martin Scurr, lead author, said the study highlighted the potential for more accurate assessment of an individual’s immunity to Covid-19.

“Many individuals worry about their risk of contracting Covid-19, whether they have been vaccinated or not.

“Our test identified that it is the level of T-cell response induced by prior vaccination or infection that is associated with the risk of that individual contracting Covid-19 in the months following the blood test.”

T-cells are a white blood cell which stores the details of a past infection and can multiply on re-exposure. They can also fight variants.

While antibodies wane over time, T-cell responses are more resilient. However, it has been challenging to test T-cell responses on a large scale.

The new test used a simple fingerprick blood sample collected at home and sent to a laboratory.