Cases of the COVID-19 virus in the U.S. have doubled in three days, climbing past 50,000 according to the latest figures from Johns Hopkins University. On Sunday, there were 26,000 cases reported. The U.S. death toll has surpassed 500, with more fatalities in New York, Washington state and other states.

The World Health Organization (WHO) warned on Tuesday that the U.S. has the potential to experience a widespread outbreak, noting the country was seeing a “very large acceleration” in infections.

The virus, which was first reported in China’s Wuhan city in the province of Hubei, has spread to nearly 400,000 people across at least 169 countries. Over 103,000 have recovered from infection, while the death count has surpassed 17,200. More cases have been reported outside China than within.

When asked whether the U.S. could become the new epicenter of the virus, WHO spokeswoman Margaret Harris told reporters: “We are now seeing a very large acceleration in cases in the U.S. So it does have that potential,” Reuters reports.

The virus has spread to all 50 states, as well as Washington, D.C., and U.S. territories including Puerto Rico, Guam and the U.S. Virgin Islands, according to the latest figures from the U.S. Centers for Disease Control and Prevention (CDC).