In the latest study, the team tried to find out why so many people have been re-infected with omicron, often quite soon after their initial attack.
The team looked at blood samples from health workers in the UK who received three doses of mRNA vaccine and had a different history of infection to investigate the immunity of antibodies, T cells and B.
They found that in triple-vaccinated people who had no previous infection, an omicron infection provided an immune boost against earlier variants such as alpha, beta, gamma, delta, and the original ancestral strain, but virtually nothing against Omicron itself.
People infected during the first wave of the pandemic and then with omicron also had no immune boost, an effect that researchers have called “hybrid immune damping.”
“Omicron could mutate even further into a more pathogenic strain”
Professor Rosemary Boyton, of the Imperial Department of Infectious Diseases and lead author, said: “Getting infected with omicron does not provide a powerful boost to immunity to omicron reinfection in the future.
“One concern is that omicron could mutate even further into a more pathogenic strain or be better able to bypass vaccine protection.
“In this scenario, people who have had an omicron infection would have little boost against future infections based on their immune impression.”
The research was published in the journal Science.