The White House Coronavirus task force is testifying live before Congress Tuesday.

Dr. Anthony Fauci said in his opening remarks that aggressive work is well underway on finding possible treatments and a vaccine for the deadly coronavirus.

Testifying via video conference in a Senate hearing, the NIH veteran warned about being too hasty with vaccines.

He said there’s a possibility that “negative consequences with certain vaccines can actually enhance the negative effect of the infection.”

Fauci is a top member of the White House coronavirus task force. He noted that progress on current vaccine trials could be known by the late fall or early winter.

CDC Director Robert Redfield testified that the nation’s “public health infrastructure” must be rebuilt. He also said the U.S. must remain vigilant about social distancing. He called it an imperative.

The White House has released a phased plan for states to follow, but many states are moving on with their own reopening plans.