COVID-19 vaccine boosters improve protection to as much as 75% against a rapidly spreading omicron variant that’s much more likely to bypass two doses than earlier strains, preliminary U.K. data show.
The basic course of shots from AstraZeneca PLC and the Pfizer Inc.-BioNTech SE partnership provided much lower defenses against symptomatic infection with omicron, compared with the delta strain, the initial study showed. A booster lifted protection to 70% to 75% in the early days after the shot.
"These early estimates should be treated with caution, but they indicate that a few months after the second jab, there is a greater risk of catching the omicron variant,” Mary Ramsay, head of immunization at the U.K. Health Security Agency, said in a statement.