By Reuters Reuters) - The Trump administration, while insisting the risk to Americans from coronavirus is low, nevertheless declared a public health emergency on Friday and announced the extraordinary step of barring entry to the United States of foreign nationals who have traveled to China. A young resident of Chinatown wears a surgical mask in New York City, U.S., January 31, 2020. REUTERS/Bryan R Smith In addition, starting on Sunday U.S. citizens who have traveled within the past two weeks to China’s Hubei Province - epicenter of the coronavirus epidemic - will be subject to a mandatory quarantine of 14 days: the incubation period of the virus, officials said. The emergency measures were unveiled by U.S. Health and Human Services Secretary Alex Azar at a White House briefing, shortly before the Centers for Disease Control and Prevention (CDC) and local health authorities announced a seventh U.S. coronavirus case had been confirmed in Northern California. The latest U.S. patient was identified only as a man in Santa Clara County, south of San Francisco, who became ill after traveling to China, and has “self-isolated” at home, Sara Cody, director of public health for the county, told reporters. She said the CDC was seeking to determine whether the man was infectious while flying home. In addition to the U.S. entry ban on foreign travelers to China and quarantine orders for Americans returning from Hubei, Azar also said all commercial flights from China would be restricted to seven U.S. airports. “The actions we have taken and continue to take complement the work of China and the World Health Organization to contain the outbreak within China,” Azar said. CDC Director Robert Redfield told reporters the U.S. government acted after the World Health Organization declared a global health emergency on Thursday over the spread of the respiratory disease. “I want to emphasize that this is a serious health situation in China, but I want to emphasize that the risk to the American public is currently low,” Redfield said. “Our goal is to do all we can do to keep it that way.” Nearly 200 Americans evacuated from China earlier this week and voluntarily confined to a military air base in California for 72 hours of coronavirus screenings were placed under a mandatory 14-day quarantine on Friday. The CDC’s quarantine in California, the first imposed by the agency in 50 years, came a day after the State Department issued its strongest warning against travel to China due to the coronavirus outbreak, which has claimed more than 200 lives. None of the U.S. cases have been fatal, and all but one of the patients contracted it while they were traveling in China.