Scientists Explore SARS-CoV-2 Mega Vaccine

Scientists from the University College London are conducting research into the possibility of creating a vaccine that activates immune memory cells, also called T cells, to prevent the escalation of SARS-CoV-2 in persons exposed to the virus.

The discovery suggests that harnessing proteins that can generate T cell production could eventually result in a vaccine that targets not just SARS-CoV-2 but also its variations, even the ones that cause common colds. 

The discovery is borne from COVIDsortium, an observational study by scientists from UCL and St. Bartholomew's Hospital, which examined 731 health workers during the start of the COVID-19 pandemic. They had found that, while the workers had been exposed to the virus, many of them did not test positive. 

Some were also observed to have developed large and broad T cells responses after possibly being exposed, although they did not test positive on PCR tests or generate antibodies. Instead of avoiding infection, these workers experienced a transient abortive infection, which is not typically seen by routine tests. 

"Our research shows that individuals who naturally resisted detectable SARS-CoV-2 infection generated memory T cells that target infected cells expressing the replication proteins, part of the virus’s internal machinery. A vaccine that can induce T cells to recognize 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 recognize other coronaviruses that currently infect humans or that could in the future," said Prof. Mala Maini, senior author of the study and part of UCL Infection & Immunity program. 

The scientists recommended further study into the potential of next generation vaccines that can induce both antibodies to target spike protein and memory T cells to target replication proteins. This duality could offer more flexibility against mutations. T cells are also long-lived, which entails longer-lasting immunity. 

The human body will typically have pre-existing T cells after experiencing viral infections, like common colds, throughout a lifetime. This effectively gives a person a good head start in strengthening the immune system against COVID-19 and its variants, and the next step would be to find a way to harness these. 

"It could be due to the infection history of these individuals. The health care workers that were able to control the virus before it was detectable were more likely to have these T cells that recognize the internal machinery before the start of the pandemic. These pre-existing T cells are poised ready to recognize SARS-CoV-2," added Dr. Leo Swadling, the lead author of the study. 

The findings are published in Nature.