"Our study indicates that vaccine effectiveness is lower against the South African variant," Adi Stern, study author and professor at Tel-Aviv University's Shmunis School of Biomedicine and Cancer Research, told ABC News. Researchers couldn't pinpoint how much lower that effectiveness might be, but Stern said she did not believe the reduction to be dramatic.
"This variant remains very rare in Israel, where vaccination percentage is very high," she added.
For the B.1.1.7 variant first detected in the U.K., "vaccine effectiveness remains high" among the fully vaccinated, according to the study.
But experts say that for the small number of people who experience breakthrough infections, vaccines protect against severe illness.
"What we do know, when breakthrough infections do occur, they tend to occur with fewer symptoms," CDC director Rochelle Walensky said during a Monday press briefing.
