Novel findings could lead to the development of a pan-coronavirus vaccine that protects against not only SARS-CoV-2 and its variants, but also common cold and emerging new coronaviruses.

To prevent the spread of the virus, according to scientists from the University College London-UCL, next-generation vaccines for Covid-19 should try to generate an immune response against replication proteins, which are necessary for the early phases of the viral cycle.

The study, published in Nature, notes that by designing vaccines that activate immune memory cells, known as T cells, to attack infected cells expressing the replication proteins, parts of the virus’s internal machinery, it might be possible to eliminate SARS-CoV-2 early on.

Senior author Professor Mala Maini explained: “These proteins – required for the earliest stage of the virus’s life cycle, as soon as it enters a cell – are common to all coronaviruses and remain ‘highly conserved’, so are unlikely to change or mutate.

“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.

“T cells recognising the virus’s replication machinery would provide an additional layer of protection to that provided by the spike-focused immunity that is generated by the already highly efficacious current vaccines.

“This dual-action vaccine would provide more flexibility against mutations, and because T cells can be incredibly long-lived, could also provide longer-lasting immunity.

“By expanding pre-existing T cells, such vaccines could help to stop the virus in its tracks at a very early stage.”

According to lead author, Dr Leo Swadling, of UCL Division of Infection & Immunity: “The healthcare workers that were able to control the virus before it was detectable were more likely to have these T cells that recognise the internal machinery before the start of the pandemic.

“Previous common cold exposure may have given these individuals a head start against the virus, tipping the balance in favour of their immune system eliminating the virus before it could start to replicate.”

This fundamental scientific discovery comes from an observational study led by UCL and the St Bartholomew Hospital which analyzed immune responses in a large cohort of London-based healthcare workers since the beginning of the first UK pandemic wave.

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