In light of a major measles outbreak in Texas, health officials in the tri-state and across the country say they are keeping a close eye on the increased number of cases.

Most cases diagnosed this year have been in Texas, where there have been more than 120. On Wednesday, a school-age child died in the state, which marked the country's first death from the disease since 2015.

There have been cases in seven states this year, including in New Jersey and New York. Connecticut has not seen a case yet.

Measles is an airborne illness. Symptoms include a rash of red spots, fever, cough and red watery eyes. People with serious cases can experience seizures, confusion and difficulty breathing.

The Centers for Disease Control and Prevention says measles is so contagious that if one person is infected, it's likely 9 out of 10 people nearby will get infected if they do not have immunity. Every Friday, the agency's measles case count map is updated online.

Texas officials say they are urgently trying to contain the outbreak.

"We're taking this very seriously and using many resources to try to contain it. We know that the MMR vaccine…is very effective and provides long-lasting immunity, long-lasting protection, and so we are trying to really get that vaccine out to all the people in that region who might not be up to date on their measles vaccine," says Dr. Jennifer Shuford, the Texas health commissioner.

The MMR vaccine is given in two doses. Doctors say after the first dose, patients are 93% protected against the diseases and 97% protected after the second shot.

Vaccines are available at doctor's office or at pharmacies.