A public health expert warned that schools could not safely reopen in the fall until the White House delivers on its promise made as states began shutting down two months ago.

Nadia Abuelezam, an epidemiologist and professor at Boston College's School of Nursing, told MSNBC's "Morning Joe" that President Donald Trump's administration had squandered up to eight weeks of lockdowns in some states.

"The reason why we've been in lockdown -- there are a number of reasons," Abuelezam said. "One is to let the health care system keep up with the demand. Another reason is, hopefully, to buy a little bit of time, to start improving our testing capacity, start improving our capacity to contact trace and isolate people who are positive. Certainly, an improvement in our testing, whether that's sort of quick diagnostic testing, or whether that's sort of quick diagnostic testing, or whether that's providing a landscape of test, trace and isolate."

"I think these are all things that we should be thinking about improving during this time of lockdown," she added. "As you've mentioned, some states decided to move out of lockdown without that supply chain and also without a system in place, to try to prevent new infections and spread in these areas."

As a result, Abuelezam said, individuals should continue to practice social distancing for the foreseeable future.

"I think a lot of this, again, depends on the system that we can have in place, to be able to test people, to be able to contact trace and make sure we're protecting all of the potential contacts, to be able to isolate people, and then also to be able to treat and support people," she said. "Really, the timeline is going to depend on our ability to get the system in place."

"I do think that this is going to be a bit of a longer lasting epidemic than people might be expecting," Abuelezam added. "I think people should really plan to maintain social distancing for a bit longer, especially to protect their families and the vulnerable in the population. In my perspective, I don't see this epidemic ending anytime soon. I do think that a vaccine will really be needed in order to make this sort of an official stop, have an official stop to the epidemic. Again, this system needs to be in place. We need to be able to test, we need to be able to trace, we need to be able to isolate. Until that happens, I'm not sure that it would be really safe to go back to all of our normal activities."