The World Health Organization on Wednesday formally declared the coronavirus a worldwide pandemic, underscoring the pathogen’s inexorable spread across the globe as new cases and deaths rise, in a sobering admission that regional efforts to contain the outbreak have been lost.

Initially, the WHO resisted characterizing the disease as a pandemic. Yet as COVID-19’s casualty count has mounted, the organization relented. Worldwide infections have surged well above 100,000 and the death toll has spiked above 4,000.

"We have therefore made the assessment that #COVID19 can be characterized as a pandemic,” said Tedros Adhanom Ghebreyesus, the World Health Organization’s director general. He added that 90% of the total cases globally are from four countries. That includes China, South Korea and Italy— which just this week was forced to quarantine the entire nation.

“In the days and weeks ahead, we expect to see the number of Covid-19 cases, the number of deaths, and the number of affected countries climb even higher,” the organization said.

The WHO’s declaration comes as efforts to contain and mitigate the coronavirus’ spread enter a new and more perilous phase. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told Congress on Wednesday that the worst was yet to come for the U.S.

In hotspots like New York — which currently is the largest epicenter of new infections — businesses have been allowing employees to work from home as new cases spike.

And around the nation, places like Harvard, Stanford and other universities have moved to online classes — effectively shuttering their campuses to students as more cities implement “social distancing” policies that keep most citizens from assembling in large groups. A range of major events, such as Coachella and South by Southwest, have either been postponed or canceled.

In the U.S., President Donald Trump has mobilized a task force to tackle the crisis, and last week signed a stimulus bill worth over $8 billion as the disease emerges as a serious challenge to his presidency.

The administration is also planning several supplemental stimulus measures to put more money in the hands of consumers, and backstop businesses hammered by travel restrictions, quarantines and border closures.

WHO’s Michael Ryan and Maria Van Kerkhove said basic public health techniques would be most effective, as seen in Singapore, South Korea and China.

Ryan said social distancing measures, like “locking down whole areas, canceling all sporting events, canceling religions events and closing schools” were more costly to a country than contact tracing — which focuses on the immediate circle of contact for an infected individual.