Blood taken from people who had been given the vaccine neutralized an engineered version of the virus that contained the same mutations carried on the spike portion of the highly contagious P.1 variant first identified in Brazil, the study conducted by scientists from the companies and the University of Texas Medical Branch found.

The scientists said the neutralizing ability was roughly equivalent the vaccine’s effect on a previous less contagious version of the virus from last year…

In previously published studies, Pfizer had found that its vaccine neutralized other more contagious variants first identified in the United Kingdom and South Africa, although the South African variant may reduce protective antibodies elicited by the vaccine.