More than 100 people and residents of almost two dozen states have contracted measles so far this year, The Centers for Disease Control and Prevention (CDC) said on Wednesday.
107 D.C. residents and people from multiple U.S. states have contracted the viral infection as of July 14.
States that have had had measles cases this year include Arkansas, California, Connecticut, Florida, Illinois, Indiana, Kansas, Louisiana, Maryland, Michigan, Missouri, Nevada, New Jersey, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, Tennessee, Texas and Washington.
The outbreak is being monitored by the agency, Fox 59 reported, explaining that the better part of patients with the virus weren't vaccinated.
The virus can be spread easily.
"Measles virus can live for up to two hours in an airspace where the infected person coughed or sneezed," according to the CDC. "Measles is so contagious that if one person has it, 90% of the people close to that person who are not immune will also become infected."
There's no specific treatment for measles, but the Mayo Clinic recommends using fever reducers, antibiotics and Vitamin A to treat symptoms.
One way to reduce your measles risk: getting the measles, mumps and rubella (MMR) vaccine.
"Two doses of MMR vaccine are 97% effective against measles and 88% effective against mumps," the CDC says. "One dose of MMR vaccine is 93% effective against measles, 78% effective against mumps, and 97% effective against rubella."
However, getting the infection is still possible.
"About 3 out of 100 people who get two doses of MMR vaccine will get measles if exposed to the virus," the agency notes. "However, they are more likely to have a milder illness, and are also less likely to spread the disease to other people."
Fox News’ Jennifer Earl contributed to this report.