(CNN) Across the country Wednesday, communities took steps to mitigate the spread of the novel coronavirus that has killed dozens of US citizens and infected more than 1,200 Americans.

Some cities and counties banned large gatherings, while basketball teams learned they would be playing in empty arenas. That is, if they were playing at all.

The NBA announced that its season is being suspended for an unspecified time following the positive coronavirus test of a Utah Jazz player, according to a statement from the league.

The halt to the schedule begins Thursday, with many teams having about 17 or 18 games left in the regular season.

In Washington, President Donald Trump restricted travel from Europe for 30 days, beginning Friday at midnight.

From the Oval Office in the White House, Trump said : "I will never hesitate to take any necessary steps to protect the lives, health and safety of the American people. I will always put the well-being of America first. If we are vigilant and we can reduce the chance of infection, which we will, we will significantly impede the transmission of the virus."

"The virus will not have a chance against us."

The President announced a 30-day ban on travelers from Europe to the United States who have been in certain countries in the 14 days before they arrive in the US. It does not apply to US citizens and permanent residents and passengers from the United Kingdom and other countries.

More than 1,200 cases

Trump's national address came the same day that the World Health Organization declared a pandemic , something it had not done for 11 years.

A pandemic is defined as the "worldwide spread" of a new disease.

The US has had more than 1,200 cases of novel coronavirus. And growing clusters of the disease are forcing many Americans to change their daily lives.

One of the biggest sports events of the year, the men's Division I basketball tournament , known as March Madness, will be played with only family members and essential personnel in attendance, NCAA President Mark Emmert announced. The women's tournament also will be played to largely empty arenas.

"While I understand how disappointing this is for fans of our sports, my decision is based on the current understanding of how Covid-19 is progressing in the United States," he said.

No big crowds allowed

Washington Gov. Jay Inslee announced Wednesday the ban on events with more than 250 people in King, Snohomish and Pierce counties.

The Seattle Sounders of Major League Soccer announced that their March 21 match against FC Dallas will be rescheduled for later in the regular season, which ends in early October. The San Jose Earthquakes, who play in California's Santa Clara County, made a similar announcement Wednesday.

Some California cities and counties have similar bans.

The NBA's Golden State Warriors, who play in San Francisco, won't have any fans at Thursday's game against the Brooklyn Nets, according to league spokesman Mike Bass.

San Francisco is halting group gatherings of 1,000 people or more in an effort to slow the spread of novel coronavirus, Mayor London Breed announced.

The San Jose Sharks will play their next three games without fans, the team said.

Several cities canceled their St. Patrick's Day parades, including Boston, Dallas, New Orleans, Pittsburgh and Savannah, Georgia. Chicago officials called off the parade and said they won't dye the Chicago River green this year.

And several universities have told students on spring break not to return to campus and be ready to take classes online.

'It is the hot spot in the nation'

New York Gov. Andrew Cuomo declared a 1-mile "containment" area in the suburb of New Rochelle, where more than 100 residents have been infected.

He's deploying the National Guard to help clean public spaces and deliver food to homes in the suburb of about 80,000 people.

"It is the hot spot in the nation" for coronavirus, Cuomo said.

The rapid outbreak in New Rochelle started with one resident -- an attorney who works in Manhattan . His wife, children and neighbor are among the dozens infected.

The containment protocols, which start Thursday, include closing schools, houses of worship and other large gathering facilities.

The 1-mile radius originates from Temple Young Israel.

People can move freely within the area. Cuomo told CNN "People can come, people can go, there's no limitation on movement, but no large gatherings because the large gatherings are where it spreads."

The protocols end March 25.

Where the cases are now

More than 1,200 cases are spread across at least 42 states and the District of Columbia.

At least 38 people have died: 30 in Washington state, four in California, two in Florida, one in New Jersey and one in South Dakota.

But the number of confirmed cases is expected to rise significantly because there has been a major backlog in testing. So some people with coronavirus might not even know it.

"We have very little access to testing," Dr. Carlos Del Rio, a professor of medicine and global health at Emory University, said Wednesday.

"I think the lack of access to testing continues to be a barrier to taking care of patients efficiently and rapidly."

Vice President Mike Pence said Monday that another 4 million tests would be available by the end of the week. He said that's on top of at least 1 million tests already in place across the country.

"We don't know exactly how many, because hundreds of thousands of our tests have gone out to private labs and hospitals that currently do not report" to the US Centers for Disease Control and Prevention, Azar said.

He said the government is now working with the CDC to create a reporting system to help "keep track of how many we're testing."

A delay in testing came after the CDC had to remake a part of the testing kits sent to states after some were deemed faulty.

It wasn't until this week that public health labs in all states were able to test for the virus.

Del Rio said the testing difficulties are exacerbating the outbreak.

"There was a lot of failure. There's been a lot of mishap in the developing of tests by the CDC," he said. "Catching up will not be easy."

Cruise ships propose new guidelines to government

The cruise industry has been hit hard by coronavirus after outbreaks on at least two ships.

Wednesday, some passengers from the Grand Princess cruise ship arrived at the Dobbins Air Reserve Base in Georgia to begin their quarantine.

More than 2,000 passengers will be placed in quarantine at multiple military bases for two weeks. The ship docked this week in Oakland, California, 21 people on board tested positive.

On a sister ship, the Diamond Princess, more than 700 people were infected with coronavirus. At least seven of those patients have since died.

The cruise industry suffered another blow when the Department of State urged Americans to not go on cruises

"Like many other viruses, Covid-19 appears to spread more easily between people in close quarters aboard ships," the CDC said.

Pence said the cruise line industry has proposed new measures such as advanced screening and upgraded medical services aboard each ship.