More than 290 million students from prekindergarten through 12th grade globally have had their education disrupted by school closures amid the continuing spread of a new coronavirus, a figure the U.N. agency dealing with the crisis says is unprecedented.

As of Wednesday, 11 countries and the Chinese administrative districts of Hong Kong and Macao had shut all schools, affecting 290.5 million children, according to UNESCO. Italy said Wednesday it was closing all schools after more than 105 people there died of the virus, joining countries including China and Japan.

Other countries implemented localized school closures, and if those countries were to order nationwide closures, 180 million more children would be out of school on three continents, UNESCO said.

“We are working with countries to assure the continuity of learning for all, especially disadvantaged children and youth who tend to be the hardest hit by school closures,” UNESCO Director General Audrey Azoulay said in a statement. “While temporary school closures as a result of health and other crises are not new unfortunately, the global scale and speed of the current educational disruption is unparalleled and, if prolonged, could threaten the right to education.”

The virus, which causes the disease known as covid-19, has infected tens of thousands of people globally after being detected in China on the last day of 2019. More than 3,000 people have died of the disease, which the World Health Organization says is a death rate of 3.4 percent, higher than previously estimated.

The death toll in the United States reached 11 on Wednesday after California announced its first coronavirus-linked death. The previous 10 were in Washington state.

Los Angeles County declared a health emergency as six new cases of coronavirus were reported there. New York had four new cases. As the virus spreads, there are fears of increasing disruptions to the routines of Americans.

U.S. schools are starting to take precautions to prevent virus outbreaks, including canceling trips, teaching students to wash their hands for an appropriate period of time with soapy water and sending reassuring messages to parents. A few schools have closed, and others are considering doing that if necessary.

These countries and administrative regions have closed all schools, UNESCO said: Armenia, Azerbaijan, Bahrain, China, Hong Kong, Macao, North Korea, Iran, Iraq, Italy, Japan, Kuwait and Lebanon.

Some schools have been closed in parts of these countries: France, Germany, South Korea, Singapore, Thailand, the United Kingdom, the United States and Vietnam.

Daniel A. Domenech, executive director of AASA, an association for school administrators, told The Washington Post that his organization has fielded at least 60 inquiries about closures. He said he tells administrators to close when anyone in a school community contracts the coronavirus.

On Wednesday, congressional negotiators reached agreement on an $8.3 billion emergency spending bill to fight the virus, aiming to have legislation ready for President Trump to sign by the end of the week.