Researchers at the La Jolla Institute for Immunology (LJI) discovered that four of the COVID vaccines (Novavax, J&J/Janssen, Moderna, and Pfizer-BioNTech) stimulate the body to produce SARS-CoV2 fighting T-Cells s, which identify SARS-CoV2 variants such as Delta and Omicron.
“The vast majority of T cell responses are still effective against Omicron,” says Alessandro Sette, Dr. Biol.Sci., LJI Professor and study co-leader.
According to Professor Shane Crotty, Ph.D, LJI,“These cells won’t keep you from getting infected, but they will keep you from getting very sick in many cases.”
“And this is true for all of the vaccines we looked at—and for up to six months after vaccination,” says Alba Grifoni, Ph.D.,LJI Instructor, responsible for co-leading the study.
This data has been collected from fully vaccinated adults who haven’t received booster shots. Studies are now being conducted to observe T cell responses in boosted subjects and those with “breakthrough” COVID-19 cases.
The new study also found that people who have been fully vaccinated have fewer memory B cells and neutralizing antibodies against the Omicron variant. This finding is consistent with preliminary reports of waning immunity from laboratories all over the world.
Omicron is more likely to cause a breakthrough infection if there aren’t enough neutralizing antibodies. With fewer memory B cells, the body will be slower to produce additional neutralizing antibodies to combat the virus.
How do T cells combat Omicron?
The good news is that neutralizing memory and antibodies are both effective. The body contains an “adaptive immune response” that has two components of which B cells are one. T cells do not protect against SARS-CoV-2 infection in people who have been exposed to it. Instead, they detect and destroy infected cells, preventing the virus from multiplying.
The LJI team believes that the “second line of defence” provided by T cells explains why Omicron infections are less likely to result in severe disease in people who have been fully vaccinated.
The scientists closely examined how the T cells responded to different viral “epitopes” to determine how effective the vaccine-induced T cells were against the Delta and Omicron.