Confirmed COVID-19 cases in the U.S. surpassed 100,000 Friday, doubling in just three days as the pandemic accelerates and the U.S. rolls out broader testing measures.

Data from Johns Hopkins University showed the total number of coronavirus cases as 101,707 and the total number of deaths in the U.S. as 1,544.

The virus emerged in Wuhan, China, in December. It has since spread to more than half a million people in almost every country around the world and continues to pick up speed, the World Health Organization warned earlier this week.

"The pandemic is accelerating," WHO Director-General Tedros Adhanom Ghebreyesus said Monday at a press briefing from the organization's Geneva headquarters. "It took 67 days from the first reported case to reach 100,000 cases, 11 days for second 100,000 cases, and just four days for the third 100,000 cases."

Confirmed U.S. cases passed 50,000 on Tuesday, up from 5,000 last week. At the beginning of the month, there were roughly 100 confirmed cases in the U.S. On Thursday, confirmed cases in the U.S. surpassed that of both China and Italy, making it the country with the largest outbreak in the world.

The number of confirmed cases likely underestimates the true number of infections across the country, officials have acknowledged. Testing in the U.S. has been hampered by delays and a restrictive diagnostic criteria that limits who can get tested.