As global deaths from the coronavirus topped 70,000, Germany's leader said the European Union was facing its "biggest test," while U.S. officials warned that the country would experience its hardest week yet.
German Chancellor Angela Merkel said Monday it is too early to consider ending restrictive measures put in place to stop the spread of the virus. Merkel called for European leaders to stand together.
"In my view ... the European Union stands before the biggest test since its founding," Merkel said.
In Britain, Prime Minister Boris Johnson, who last week tested positive for coronavirus, was moved to intensive care after his conditioned worsened Monday.
A statement from Downing Street said Johnson asked Foreign Secretary Dominic Raab "to deputize for him where necessary."
Johnson's office did not say on Monday what treatments the 55-year old prime minister is receiving. It had previously said he was hospitalized with a persistent fever and was undergoing tests as his symptoms had not improved.
Britain has emerged as one of the latest hot spots in the pandemic, reporting more than 400 deaths Monday.
Other parts of Europe showed some improvement after weeks of devastating impacts from the virus that have caused governments to put residents on lockdown to try to slow its spread.
Spain reported its latest in a string of lower daily death and new infection counts, while France recorded its fewest deaths in a week. Italy reported a jump in new fatalities Monday with 636 deaths, after a weekend of its lowest toll in two weeks.
The United States on Monday topped 10,000 total deaths, making it the country with the third-highest official death tally, behind only Italy and Spain.
About one-third of the U.S. deaths have been in New York City, where makeshift field hospitals and a U.S. Navy medical ship are trying to take some of the strain off the city's health care system.
U.S. Surgeon General Jerome Adams warned Sunday that the coming week will be "our Pearl Harbor moment, our 9/11 moment."
Other parts of the country are emerging as concerns with mounting case numbers, including Pennsylvania, Colorado and Washington, D.C., where about 1,000 cases have been confirmed.
The Pentagon said Monday that the number of coronavirus cases in active duty troops topped 1,000 over the weekend.
The growing number of coronavirus cases around the world has led many governments to recommend or require their citizens to wear face masks. However, the World Health Organization warned Monday that wearing masks alone would not be enough to stop the pandemic.
"Masks should only ever be used as part of a comprehensive package of interventions. … Masks alone cannot stop the COVID-19 pandemic," WHO Director-General Tedros Adhanom Ghebreyesus told a virtual news conference.
South Korea, one of the first hot spots in the outbreak, reported just 47 new cases Monday, but the country's vice health minister cautioned the need for continued vigilance and for people to stay home to prevent an infection "explosion."
Kim Gang-lip said data from smartphones showed too many people were going out to restaurants and parks in recent weeks.
Nearby Japan has recorded 3,600 cases so far, but there are heightening concerns about certain parts of the country, including Tokyo, where those numbers have been increasing more rapidly.
Japanese Prime Minister Shinzo Abe said his government plans to declare a state of emergency as early as Tuesday in Tokyo and six other areas. It would last for about one month and involve calls for people to stay home. The government also plans an economic aid package worth about $1 trillion.
One country on the opposite end of the spectrum is Austria, where officials said Monday they are considering starting to lift lockdown orders to allow smaller shops to open next week and the rest of the stores in the country to open again on May 1. Austria has confirmed 12,000 cases.
Meanwhile, United Nations Secretary-General Antonio Guterres is urging governments to take steps to protect women after a "horrifying" increase in domestic violence during the outbreak.