The U.S. Food and Drug Administration's top vaccine official, Vinay Prasad, has left the agency after just three months as Director of the Center for Biologics Evaluation and Research, a government spokesperson said.

Dr. Vinay Prasad, the controversial critic of the US Food and Drug Administration who took a top role at the regulatory agency in May, has resigned less than three months into the job.

Dr. Vinay Prasad had been serving as the FDA's director of the Center for Biologics Evaluation and Research since May, and was later named chief medical and scientific officer.