Combined SARS-CoV-2 T cell & antibody capillary blood test for high-throughput population immunity screening

As the current COVID-19 pandemic unfolds, we urgently require screening tools that determine who is sufficiently protected from the SARS-CoV-2 virus, which causes the disease. To enable the population and the economy to return to normal, it is important to know who has become immune to the virus through infection or vaccination. This includes individuals who have already been infected, in many cases without realising it.

In order to gain immunity to SARS-CoV-2, an individual must generate an adequate immune response that protects from future infection. This can be measured by looking for antibodies found in blood samples that bind specifically to the virus. However, antibody responses naturally wane over time, and there are increasing instances of COVID-19-positive individuals no longer having detectable antibodies.

Long-term protection against viruses not only comes from antibodies, but from cells of the immune system called 'T cells', which play a critical role in controlling and eradicating viral infections. There is an increasing acceptance amongst immunologists that a T cell response is longer lasting and must also be present to constitute effective, protective immunity. The magnitude and durability of a T cell response that protects against reinfection remains unknown, but is an area of fervent international interest.

Ordinarily, techniques that measure T cell responses are laborious, hard to standardise, expensive and labour-intensive. This project will establish an at-home, finger-prick COVID-19 immunity assay that identifies the presence of both SARS-CoV-2-reactive T cells and antibodies from a single capillary blood sample. A simple, effective measurement of an individual's T cell and antibody response to SARS-CoV-2 would revolutionise our understanding of what constitutes protective immunity to COVID-19\.

In addition, as vaccines are rolled out, results from the test developed here will yield critical additional information as to whether an adequate immune response that protects individuals from SARS-CoV-2 infection, including mutated variants, has been generated. This product would enable large scale immunity testing to be performed, crucial for assessing population immunity, monitoring vaccine efficacy, and more broadly resuming a normal lifestyle.