WASHINGTON, May 17 (Xinhua) -- "If we do not have expanded testing in place, we will be flying in the dark, once again. We have already seen how that comes out," a leading U.S. epidemiologist said Sunday.

Robert Schooley, a professor of medicine with the Division of Infectious Diseases and Global Public Health at the University of California, San Diego, told Xinhua in an interview that the biggest challenges facing the United States are having the patience and the wisdom to wait long enough to reopen, and having enough testing in place to react quickly if a flare in transmission occurs.

As many states across the United States are lifting stay-at-home orders and reopening businesses, many experts are concerned that the failure to flatten the curve and drive down the infection rate in places could lead to many more COVID-19 deaths.

"I fear that we will see flares as we race to get back to work in places where the number of new cases has not fallen sufficiently," Schooley said.

Recently, many influential COVID-19 models cited by the U.S. Centers for Disease Control and Prevention (CDC) have raised death projections.

The National Ensemble Forecast suggests that the number of cumulative reported COVID-19 deaths are likely to exceed 100,000 by June 1.

"State-level ensemble forecasts indicate that states with low numbers of deaths reported to date are not likely to see a rapid rise in the coming weeks, while states with high numbers of deaths reported to date are likely to see substantial increases," said the CDC.

The model produced by the Institute of Health Metrics and Evaluation of the University of Washington, often cited by the White House, projected 147,040 COVID-19 deaths by Aug. 4.

New York, New Jersey, Pennsylvania, Massachusetts and Michigan are projected to have the highest cumulative COVID-19 death tolls through August.

Schooley said projections regarding COVID-19 case rates have continued to fluctuate for a number of reasons.

"There are still areas in the United States where testing is more limited than it should be which has artificially held down the case reporting rate," he noted.

Furthermore, as a number of states reopen their economies and allow a resumption of a number of activities, it would not be a surprise to see the result be a reversal of the epidemic curve, Schooley said.

This has been observed in a number of places in which people resumed activities when virus was still circulating, he said, citing countries including Singapore, Japan and South Korea.

"There is a good chance that we will also see some of this in the United States," Schooley added.

Without a vaccine or cure, staying away from infected people is the effective way to stop the virus. Across the country, states that instituted stay-at-home orders have seen plateaus or slower-than-expected declines in COVID-19 cases.

"The restrictions really do work when people follow them assiduously," Schooley said.

New Zealand and Australia are the most recent examples of how successful distancing can be if people take it seriously and do it for long enough, he told Xinhua.

Still, many states, after weeks of shutdown measures, are already moving to loosen these measures before the first wave of coronavirus has abated.

"Our biggest challenges are having the patience and the wisdom to wait long enough to return to work and school, and having enough testing in place to react quickly if there is a flare in transmission," Schooley noted.