Overview
- Cambridge researchers tested blood from older UK adults who had four vaccine doses, including a bivalent Wuhan/Omicron booster, and found the samples neutralised two sarbecoviruses from bats and pangolins.
- The same antibodies were much less effective against recent Omicron variants and were poor at neutralising SARS‑CoV‑1, showing that viral evolution has weakened vaccine-era protection for some strains.
- A separate Cambridge study found that a person’s first SARS‑CoV‑2 exposure, whether infection or vaccine, imprints the immune system and shapes later antibody responses to new variants.
- Laboratory removal of antibodies directed at earlier strains made blood far less able to neutralise both older variants and Omicron, confirming that new responses are built on pre‑existing immune memory.
- Researchers say these results support using boosters to reduce severity and spread after a spillover and argue for next‑generation vaccines that target conserved spike regions to give broader, more durable protection across varied exposure histories.