A new observational study, COVIDsortium, claims that future COVID-19 vaccines should activate T cells to attack infected cells expressing replication proteins, according to Drug Target Review.

The study has been published in Nature. Researchers at University College London, UK, have said that next generation vaccines for COVID-19 should aim to induce a response against ‘replication proteins’, essential for the very earliest stages of the viral cycle.

COVIDsortium analysed the immune responses in a large cohort of healthcare workers in London, from the beginning of the pandemic in March 2020. Some of these healthcare workers appeared to have a low-level infection which was undetectable by routine tests, but which generated T cells specific to SARS-CoV-2. These individuals also had a low-level increase in another blood marker of viral infection.

Through designing vaccines that activate T cells to attack infected cells, researchers found that it may be possible to prevent the spread of SARS-CoV-2, by eliminating it at the very onset of the virus.

Lead author, Dr Leo Swadling, said: “We know that some individuals remain uninfected despite having likely exposure to the virus. What we did not know is whether these individuals really did manage to completely avoid the virus or whether they naturally cleared the virus before it was detectable by routine tests.”

“By intensively monitoring health care workers for signs of infection and immune responses, we identified a minority with this particular SARS-CoV-2 specific T cell response. What is really informative is that the T cells detected in these individuals, where the virus failed to establish a successful infection, preferentially target different regions of the virus to those seen after infection.”

Senior author, Professor Mala Maini, added: “A vaccine that can induce T cells to recognise and target infected cells expressing these proteins, essential to the virus’s success, would be more effective at eliminating early SARS-CoV-2, and may have the added benefit that they also recognise other coronaviruses that currently infect humans or that could in the future.”