By Dewald Schoeman and Dr. Burtram C. Fielding, PhD, University of the Western Cape — The Conversation Africa — 1 September 2021
One important and positive aspect of COVID-19 vaccines has not been well communicated: statistics about vaccine efficacy have focused almost exclusively on one aspect of immunity — antibodies — while the role of T-cells, a key part of the immune system, has been largely overlooked. The good news is that current vaccines stimulate T-cells to fight against both the SARS-CoV-2 virus and its emerging variants in the long term. While antibodies bind to viruses and neutralise them, T-cells kill cells that have already been infected. Cell-mediated immunity is far more effective at eradicating viruses and more durable. A 2016 study demonstrated that T-cell immunity against the SARS-coronavirus persisted for up to 11 years, providing complete, effective and lasting protection.
Several recent papers have demonstrated that while SARS-CoV-2 variants could partially escape neutralising antibodies, the cell-mediated immune response induced by most currently used COVID-19 vaccines is very resilient and remained effective against variants. While antibodies induced by the vaccine were less capable of neutralising the variants, T-cells were largely as responsive to the variants as they were to the original wild-type virus — still able to recognise and respond effectively, conferring resilient protection against disease. The authors argue that greater public trust in vaccines could be built by better communicating the statistics about both kinds of immune responses, particularly the durable cell-mediated response. “Any news of decreasing antibody efficacy against emerging variants is seized upon as evidence that vaccines may not work well in the long term. This can foster a lack of trust from the public in the science behind the design of COVID-19 vaccines, and this lack of trust could contribute to vaccine hesitancy,” the authors note. Knowing that existing COVID-19 vaccines offer a resilient cell-mediated immune response can help people make an informed decision about vaccination.