Chen Xi, assistant professor from the Yale School of Public Health, told CGTN that keeping the U.S. economy open is more difficult than the economic restart. Chen said the reopening of the U.S. economy is related to two key factors: the number of tests that can be done, which can reflect the impact of coronavirus, and the country's capacity to carry out infection tests. Chen added that currently no state in the U.S. is capable of ensuring the capacity of tests.