A measles outbreak is spreading among children in southwestern Washington , amid an uptick in cases elsewhere in the country .

Health officials in Clark County have identified 16 confirmed and five suspected cases of the highly contagious viral infection since Jan. 1. Children younger than 11 accounted for 13 of the confirmed cases.

Two children have been hospitalized, including one with a suspected case of measles, which can be spread through cough or sneeze and cause fever, cough, runny nose, red eyes and a rash.

“Measles can be dangerous, especially for babies and young children. In rare cases, it can be deadly,” a fact sheet shared by Clark County Public Health says.

Fourteen of the children in Clark County – home to about 475,000 people and situated northeast of Portland, Oregon – had not been vaccinated against measles, while officials said the immunization status of the other two children was unverified.

Just over 77 percent of Clark County public school students have completed their vaccinations , The Oregonian reported , marking one of the lowest immunization rates in the state.

Roughly 95 percent of people should be vaccinated to create “herd immunity” against a contagious disease like measles, health experts say, and the Centers for Disease Control and Prevention recommends children receive their first vaccination against measles between 12 and 15 months old.

Last year, 349 cases of measles were confirmed in 26 states and the District of Columbia, the second-highest annual count since the illness was declared eliminated in the U.S. in 2000, according to preliminary data from the CDC .

In any given year with a higher case count, more measles cases may be the result of a spread in communities with “pockets of unvaccinated people,” the CDC said. Nearly everyone who has not been vaccinated against measles will be infected if they are exposed to the virus, according to the Washington State Department of Health .

In Clark County, officials warned that people who visited health clinics, emergency departments, schools, churches, the Portland International Airport and stores in the area may have been exposed to the virus.