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NBA fans who attended a Portland Trail Blazers basketball game in Oregon earlier this month may have been exposed to measles, health officials in the state said.

This comes as officials in nearby Vancouver, Washington, in Clark County said the confirmed number of measles cases in that county has climbed to 23.

Officials in neighboring Multnomah County, Oregon, said that a person known to be contagious with the disease attended a game at the Moda Center in Portland on Jan. 11 and possibly exposed people who were at the sports arena between 5:30 p.m. and 11:30 p.m. to the viral infection, said a press release posted to the Multnomah County's website..

The Oregon county is now working with the Trail Blazers to direct people concerned about possible exposure to accurate information.

People who are fully vaccinated against measles have very little risk of becoming infected. The vaccine provides upwards of 95 percent protection. But measles is one of the most infectious viruses known and will infect 90 percent of unimmunized people who breathe it in.

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Health officials in Multnomah County said the virus can linger in the air even after a contagious person has left.

“The measles vaccine is so effective,” said Tri-County Health Officer Dr. Paul Lewis said in the Multnomah County press release. “But, this is a good reminder that when you feel sick — even if it’s just a cold — it’s best to stay home to avoid making others ill.”

Those who have not had the measles before or have not been vaccinated and develop cold-like symptoms that include fever and red eyes are urged to call their doctor before going to the emergency room or urgent care.

Lewis said calling the doctor first this helps keep other people in need of medical care safe.

“By calling before you go, the staff can make sure a plan is ready when you arrive,” Lewis said.

Since Jan. 1, there have been 23 confirmed cases of the measles and two suspected cases in Clark County, Washington, according to the county public health department. A majority of those cases are people who are 1 to 10 years old, officials said. One case resulted in someone being hospitalized.

So far, there have been no confirmed measles cases in Oregon in the current outbreak, according to officials.

The Centers for Disease Control and Prevention said 2018 was the second-worst year for measles since 2000, with 349 individual cases confirmed in 26 states and the District of Columbia.

The worst year for the U.S. since the turn of the century was 2014 when there were 667 cases, according to the CDC.