"The models do show that we are very close to the peak. So I think that information is accurate," Hahn said. "This has been a really fast-moving outbreak, so we really have to take this day by day."
President Donald Trump has pushed to reopen the country as soon as possible -- at one point even suggesting Easter as a target -- but medical professionals have cautioned against reopening before even the start of May, suggesting that there could be a spike in infections if restrictions are lifted too soon.
"Wouldn't we be taking a big risk, relaxing those measures now?" "This Week" co-anchor Martha Raddatz asked Hahn.
"I think the public safety and the welfare of the American people has to come first," Hahn said.
He said that they have to look at what they know about the illness, review the data as it comes in and compare to what happened in other countries before moving forward.
"Given what you know, is May 1 a good target when you look at it now?" Raddatz asked.
"It is a target and obviously we're hopeful about that target but I think it's just too early to be able to tell that we see light at the end of the tunnel," Hahn said. "I think it's just too early for us to say whether May 1 is that date."
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Dr. Zeke Emanuel, a key architect of the Affordable Care Act and a special adviser to the director general of the World Health Organization, told ABC News that he doesn’t anticipate life fully returning to normal for another 18 months, based on guidance from health professionals in the Trump administration.
"Anyone who tells you we're going to have a vaccine in three or four months, that's just not the reality of how biology and research works," he said Wednesday.
Although some models predict Sunday to be the peak of cases of the disease, the downhill curve still implies weeks of caution from the entire nation. Without a vaccine or effective treatment, reopening the country fully could take longer than the Trump administration would like.
As the coronavirus begins to spread out of cities and into rural areas, there is still no nationwide testing program.
Hahn said the government is trying to focus testing in hotspot areas where as many as 30% to 40% of those who get tested are positive, but that the efforts will need to be expanded.
"Further ramping up testing both -- diagnostic as well as the antibody tests -- will really be necessary as we move beyond May and into the summer months and into the fall," Hahn said.
But Raddatz noted that widespread testing has already been taking place in many of the countries ravaged by COVID-19 and that rapid testing was approved by the FDA over a week ago.
"Other countries like the U.K., Germany, South Korea have been able to do testing of millions of people. Why are we still so far behind? It was over a week ago that the Abbott test -- a rapid test -- was FDA approved, it is still not in widespread use," Raddatz said. "This is preventing people from going back to work, getting out of quarantine. When exactly will it be available in every major city in the US?"
The situation is complicated and rapidly-moving, Hahn said. Not only that, but the supply chain is under strain as manufacturers try to adapt to the demand.
"We have to really, as a whole of U.S. government approach, we have to make sure that we get those (tests) to the areas that need them," Hahn said.
The United States has done more than 2 million tests, more than any other country Hahn told Raddatz.
"Now we need to do more, no question about that," he added.
While the FDA has authorized one type of antibody test, which will be able to detect if a person is immune to showing symptoms of the disease, he said there is an effort by the government underway to review information from other sources.
"There are a number that are on the market that we haven't validated, that we haven't looked at those data. There is a U.S. government effort to look at some of those tests," Hahn said.
"We're working with a number of really good manufacturers. They've come forward with their platforms. And so we do expect that relatively soon," Hahn said. "We've seen reports, other countries, some of the countries you mentioned, that have obtained antibody tests that aren't accurate. We think it's really important for the American people to know that we need tests that are accurate, reliable and reproducible. That's what FDA does in a science- and data-driven way."
Hahn said that environmental factors will be one of the key tells on someone’s immunity to the disease.
"It's one of the factors that will go into this, including the underlying characteristics of the person, whether they're more susceptible to a more serious outcome from COVID-19, where they live with the prevalence of the diseases in the environment, and whether they've had a diagnostic test that's positive previously or not," Hahn said. " So all those factors will go into it and including whether you have antibodies because that should be protected, as you point out."