HONG KONG — New walls are rising between China and the world as the country grapples with a fast-moving coronavirus and its mounting death toll.

Vietnam on Saturday became the latest country to try to close itself off from the world’s most populous country, barring all flights from and to China. Over all, nearly 10,000 flights have been canceled since the outbreak.

Australia joined the United States in temporarily denying entry to noncitizens who have recently traveled to the country. There are officially eight confirmed cases in the United States, including one person connected to the University of Massachusetts-Boston.

Japan also said it would bar foreigners who had recently been in the Chinese province at the center of the outbreak, or whose passports were issued there.