In the race to protect their populations against the Omicron coronavirus variant, countries including the UK and the US are rolling out extensive booster programmes after data showed additional jabs provided more protection against the new strain than two shots.
The latest data — from Oxford university — on Monday showed levels of neutralising antibodies that attack the virus fell against Omicron, compared with Delta, in people who had taken two doses of the vaccine it developed with AstraZeneca, or of the BioNTech/Pfizer shot.
The substantial fall in antibodies, Oxford said, “suggests that while there is no evidence of increased potential to cause severe disease, or death, increased infections in previously infected, or vaccinated individuals may be likely”.