Two doses of Pfizer and AstraZeneca COVID-19 vaccines generate lower levels of antibodies against the Omicron variant of coronavirus, according to a study which suggests that those previously infected or vaccinated may be at an increased risk of infection.
The researchers, working in an 'unprecedented' vaccine development effort to prevent COVID-19, said they have started screening healthy volunteers (aged 18-55) from Friday for their upcoming trial in the Thames Valley Region of England.