The Netherlands is battling two epidemics of the novel coronavirus: one against its existing variants, in which cases are declining, and "another epidemic involving the U.K. variant, in which infections are increasing," the Dutch National Institute for Public Health and the Environment said in a situation report released Tuesday.

The so-called U.K. variant, first identified in England last September, has caused a massive jump in COVID-19 hospitalizations in the United Kingdom and Ireland.

In the Netherlands, government officials said they were "gravely concerned about the U.K. variant." Over the weekend they introduced a nighttime curfew which has sparked riots.

Over the last two weeks, the Netherlands has reported an 11.7% positivity rate for COVID-19 tests.

ABC News’ Christine Theodorou contributed to this report.

The worldwide number of people who have been diagnosed with COVID-19 surpassed 100 million on Tuesday, according to real-time data collected by Johns Hopkins University. The United States accounts for over 25 million of those cases.

For perspective, only 14 countries in the world have populations over 100 million, according to the latest data from the World Bank Group.

The grim milestone comes just over one year since the first COVID-19 case was confirmed in Wuhan, China, on Dec. 31, 2019.

The number of people who have died from COVID-19 in the United Kingdom has surpassed 100,000, British Prime Minister Boris Johnson announced Tuesday.

"It's hard to compute the sorrow contained in that grim statistic," Johnson said.

More than 35,000 people in the U.K. are hospitalized with COVID-19, which is "substantially" above the peak in April, according to Johnson.

The number of people testing positive for the disease remains high but is decreasing slowly, with 20,089 new cases reported Tuesday, according to Johnson.

ABC News’ Christine Theodorou contributed to this report.

This year's Boston Marathon will be held on Oct. 11, if road races are allowed in Massachusetts' reopening plan at that time, according to the Boston Athletic Association.

A virtual race will also be offered as an option to runners.

"While it was of course the right thing to do, canceling the 2020 Boston Marathon for the first time in its 124-year history was one of the hardest announcements to make," Boston Mayor Marty Walsh said in a statement Tuesday.

"Today, I'm filled with hope, as we set our sights on October for the running of the 125th Boston Marathon," he added. "We have a ways to go before we're out of the woods, but guided by sound judgment and the advice of our public health experts, I am hopeful that we'll get to enjoy the return of one of Boston's most storied traditions this fall."

ABC News' Leo Mayorga contributed to this report.

There were 130,485 new cases of COVID-19 confirmed in the United States on Sunday, according to a real-time count kept by Johns Hopkins University.

Sunday's tally is the lowest daily case count that the U.S. has recorded in a month and is also far less than the country's all-time high of 298,031 newly confirmed infections on Jan. 2, Johns Hopkins data shows.

An additional 1,770 fatalities from COVID-19 were registered nationwide on Sunday, down from a peak of 4,462 new deaths on Jan. 12, according to Johns Hopkins data.

COVID-19 data may be skewed due to possible lags in reporting over the Martin Luther King Jr. Day holiday weekend.

A total of 25,127,009 people in the U.S. have been diagnosed with COVID-19 since the pandemic began, and at least 419,215 have died, according to Johns Hopkins data. The cases include people from all 50 U.S. states, Washington, D.C., and other U.S. territories as well as repatriated citizens.

Much of the country was under lockdown by the end of March as the first wave of pandemic hit. By May 20, all U.S. states had begun lifting stay-at-home orders and other restrictions put in place to curb the spread of the novel coronavirus. The day-to-day increase in the country's cases then hovered around 20,000 for a couple of weeks before shooting back up over the summer.

The numbers lingered around 40,000 to 50,000 from mid-August through early October before surging again to record levels, crossing 100,000 for the first time on Nov. 4, then reaching 200,000 on Nov. 27 before nearing 300,000 on Jan. 2.