There are now more than 2 million coronavirus cases across the globe

The coronavirus has infected 2 million people around the world, a grim milestone exposing the difficulty of trying to contain the deadly pathogen.

What began as a mysterious pneumonia-like illness in Wuhan, China, late last year has morphed into a global health crisis that has threatened health systems and economies alike.

It took about four months for the virus to infect 1 million people and only 12 days for that number to double. The total case count today is likely even higher than 2 million, with countries including the U.S. testing only a fraction of their populations.

The virus, which causes the COVID-19 disease, can in some cases spread easily and quietly. People can pass it onto others before they even know they're sick — or without ever developing a cough or fever, the disease's hallmarks.

Cases in the U.S., now more than 600,000, have dwarfed other nations. Outbreaks in major metropolitan areas like New York City, Seattle and Detroit have killed thousands and shut down American life in many regions.

European hotspots Italy and Spain continue battling outbreaks that have torn through towns and prompted nationwide lockdowns. Cases in Singapore are rising after months of successful containment.

Around the globe, the virus has crossed all walks of life. It's infected everyone from political elite like heir to the British throne Prince Charles to grocery-store clerks, musicians and prison inmates.

In the U.K., Prime Minister Boris Johnson became so sick that he was admitted to intensive care. He was released from the hospital on April 12.

World leaders are searching for ways to control the virus and reopen businesses and schools. Testing could present one way to identify and isolate people before they infect others. Long-term, leaders are pinning their hopes on a vaccine.

There are some 70 potential vaccines in development globally, with three candidates already being tested in humans, according to the World Health Organization. Still, health officials warn that it could take at least a year before one is ready.

Tension between reining in the virus and reopening the economy is perhaps most evident in the U.S., where President Donald Trump regularly airs his frustration in daily press briefings. The administration currently recommends practicing social distancing until the end of April.

Anthony Fauci, the nation's leading infectious-disease expert, has floated the possibility that parts of the U.S. may be able to start loosening restrictions in May. Concerns over a possible resurgence if governments move too quickly in returning to normal weigh on many leaders.

“There is always the possibility, as that — as we get into next fall, and the beginning of early winter — that we could see a rebound” of the virus, Fauci said on April 12.