The head of the National Institutes of Health, Francis Collins announced his resignation Tuesday morning.

Fox News reports:

“I am proud of all we’ve accomplished. I fundamentally believe, however, that no single person should serve in the position too long, and that it’s time to bring in a new scientist to lead the NIH into the future,” Collins said in a statement. “I’m most grateful and proud of the NIH staff and the scientific community, whose extraordinary commitment to lifesaving research delivers hope to the American people and the world every day.”

The 71-year-old physician-geneticist, who oversaw the research center for 12 years, aims to return to the National Human Genome Research Institute, the Washington Post reported. The lab is a branch of NIH.

Collins led the acclaimed Human Genome Project to completion in 2003 and, in recent months, he has worked to accelerate treatments for the coronavirus. In August, he appeared on “Fox News Sunday” and stressed the highly contagious nature of the delta variant, while acknowledging that vaccines are generally effective against it.

Collins went on to say that while infections of vaccinated people are rare and do not pose significant risks to those people themselves, vaccinated people who do catch it can transmit it to others. That, he explained, is why the CDC is recommending people in areas where there is high transmission to go back to wearing masks indoors, even if they are vaccinated.

Collins choice to resign from the NIH now leave the question who will replace him in the position.