A student at Northeastern University in Boston was diagnosed with measles Jan. 8.

Nearly 800 Seattle students will be kept out of school on Wednesday, their first day back after winter break, because they aren't vaccinated against measles.

Nearly 800 Seattle students will be kept out of school today, their first day back after winter break, because they aren't vaccinated against measles.

The school district issued notices, saying children would not be allowed to attend class if they did not get the necessary shots.

The government of Samoa ended the state of emergency it had declared in response to its measles outbreak that swept the small island nation of fewer than 200,000 people.

A measles outbreak has prompted officials of the Seattle Public Schools to take the drastic action of ordering thousands of students to get vaccinated immediately.

More than 2,200 students were sent letters to get vaccinated.

They said an unknown number of people who had recently traveled through at least five busy U.S. airports may have been exposed to the contagious disease.

Los Angeles, Chicago, Denver, Austin and Richmond have all reported confirmed cases of passengers with the measles this month.

Officials at airports in Austin, Denver and Los Angeles confirmed that travelers with the measles had also exposed an unknown number of fliers to the disease this month.

With a record number of Americans flying for the holidays, three major airports are warning of possible measles exposure.

Travelers at LAX were warned they may have been exposed to measles after three people infected with the disease passed though the airport last week.

Samoa arrested a local anti-vaccination activist as authorities carry out a mass vaccination campaign in the Pacific island nation in response to a measles outbreak.

More than 140,000 people around the world died of measles last year, most of them children under the age of 5, according to a new report.

The death toll from a growing measles outbreak on the small Pacific island of Samoa has topped 50.

Authorities race to vaccinate the entire population of the South Pacific nation.

The anti-vaccine movement has a history of targeting minority groups, like the Orthodox Jewish community in Brooklyn and the Somali refugee community in Minnesota.

Measles is a viral disease that is extremely contagious.

Samoa banned children from public gatherings, mandated everyone get vaccinated.

Cobb County, a suburban part of Atlanta, Georgia, confirmed a case of measles in an unvaccinated person, according to state health officials.

Dr. Jennifer Ashton is here to discuss a new study that says people who have had the measles are vulnerable to other infections up to months after they've gone away.

A measles infection changes the body's immune response, effectively erasing the immune system's memory of previous infections.

There were no new cases of measles reported last week, the Centers for Disease Control reported Monday, which marks a notable decline from earlier this year.

There were no new cases of measles reported last week, the Centers for Disease Control reported Monday, which marks a notable decline from earlier this year.

New York Mayor Bill de Blasio health officials have declared an end to the recent measles outbreak in the city in a statement released Tuesday.

Health officials declared the end of the measles outbreak in New York City.

A new report released by the World Health Organization shows that the fight against measles in Europe is on a downward slide.

The World Health Organization calls the outbreak a “dramatic resurgence” of the virus.

The new school year is starting as there are six active outbreaks and after months where recent records for the number of measles cases in the U.S. have broken records

The CDC is reporting a dozen new cases of measles over the past week, making this year the worst measles outbreak since 1992.

Public health officials say a teenager competing in the World Hip Hop Championship in Phoenix has measles and may have exposed others at the dance competition

A New Zealand teenager who visited Disneyland, Universal Studios, Hollywood tourist hot spots and the beach this month had measles and may have exposed others, public health agencies announced Friday

Dr. Jennifer Ashton discusses what parents should know about the rapidly-spreading measles cases as a new school year starts.

The number of measles cases continues to grow, though at a slightly less rapid pace than was recorded earlier in the year.

The Centers for Disease Control announced Monday that there were 21 new cases of measles in the most recent recorded week, bringing the total number to 1,203 confirmed cases.

America is in the grips of the largest measles outbreak in 25 years.

ABC News chief medical correspondent Dr. Jennifer Ashton shares what parents can do to protect their children as they head back to school.

The German government is proposing a measure to make measles vaccinations mandatory for children and employees of kindergartens and schools

The U.S. is just one country where measles outbreaks are a health concern, and a new report published today evaluates vaccine confidence around the world.

As of June 1, more than 1,000 measles cases had been reported in the U.S.

Medical exemptions, which are relatively rare, will still be in place, but non-medical exemptions including religious exemptions would no longer be allowed in the state.

Gov. Andrew Cuomo signed the removal into law Thursday, noting that the Empire State is in the midst of the worst measles outbreak in more than a quarter of a century.

The Centers for Disease Control reported Monday that there have been 1,022 cases in 28 states through June 6.

A measles epidemic has been declared in the Democratic Republic of the Congo, a country struggling to contain the world's second-largest, second-deadliest Ebola outbreak.

Dr. Jennifer Ashton discusses what you should know about the climbing figure and how it could affect your day-to-day life.

The number of measles cases reported in the first five months of 2019 has now surpassed every year since 1994, the CDC announced Thursday.

The number of measles cases reported in the first five months of 2019 has now surpassed every year since 1994, the Centers for Disease Control and Prevention announced Thursday.

This year has seen the greatest number of cases for a single year in nearly three decades.

The number of measles cases in the U.S. continues to climb but at a slightly slower rate than previous weeks.

There have been 839 cases of measles across the country, according to the CDC.