A MMR vaccine information packet is pictured in Lubbock, Texas, amid an outbreak of measles in the state in March. State officials in South Carolina reported at least 153 students are from two schools are under quarantine for 21 days due to explosure to measles. (Photo Credit: Annie Rice/EPA)

Oct. 13 (UPI) -- At least 153 unvaccinated students at two northern South Carolina schools exposed to measles are being quarantined for 21 days, state health officials said.

The students, because they didn't have immunity, will be excluded from school until the potential disease transmission period has ended, the South Carolina Department of Health Education said in a video briefing Thursday.

The schools affected are in Spartanburg County: Global Academy and Fairforest Elementary School.

The 11th case in the state was confirmed on Thursday and the eighth since Sept. 25.

"What this case tells us is that there is active, unrecognized community transmission of measles occurring in the Upstate, which makes it vital to ensure that the public have received their measles vaccinations," a release from the South Carolina Department of Public Health said.

Measles is highly contagious, with nine out of 10 people becoming infected if not vaccinated, according to the Centers for Disease Control and Prevention. Those infected are contagious four days before the rash begins and through four days after its onset.

"The virus can be spread through the air when a person with measles breathes, coughs or sneezes," the health agency said. "Measles virus can remain infectious in the air in a confined area such as a room, hallway or vehicle for up to two hours after the sick person is gone from the area. People with measles should stay home from work and school and avoid contact with others as soon as they feel sick and for four days after their rash first appears."

Symptoms usually appear seven to 14 days after contact with the virus, according to the CDC.

Initial symptoms include fever, cough, red eyes and runny nose. Then, a rash follows on the face and spreads to the rest of the body, lasting five or six days.

The measles vaccine is more than 97% effective, according to the CDC.

The combined vaccine includes measles, mumps, rubella (MMR). The first dose should be given for children 12 to 15 months of age, and the second at 4 to 6 years of age. Children 6 to 12 months also should get an early dose of MMR vaccine if they are traveling internationally or to an outbreak area, the CDC recommends.

The CDC advises certain groups of people, including pregnant women and immunocompromised people, not receive the MMR vaccine or should delay receiving it.

Before the pandemic, more than 95% of kindergarteners were vaccinated with the MMR shot, the CDC reported on July 31. That figure has now fallen to 92.5% in the most recent school year.

The number of measles cases nationwide is the most in 30 years, according to the CDC. More than of the 1,563 cases through Oct. 13 are connected to an outbreak in West Texas with 803.

In August, Texas health officials declared the outbreak over. Adjacent New Mexico has reported 100 cases, the second most in the nation.

There were only 285 cases nationwide in 2024. Since 2000, the previous most were 1,274 in 2019.

Measles was officially eliminated from the United States in 2000 after the debut of the vaccination program, meaning there is no measles spreading within the country and new cases are only found when someone contracts measles abroad and returns to the country.

They reached nearly 500,000 cases yearly in the 1960s. Nearly every child got measles by the time they were 15.

Most people born before 1957 are presumed to have protection via natural immunity, even if they have not been vaccinated.

The first vaccine was licensed in 1963 by John Enders and colleagues.

In 1968, a vaccine was distributed nationwide.

So far this year, 177,469 confirmed measles cases were reported worldwide with 359,589 last year, according to the World Health Organization. Over 12 months, the highest rate is Kyrgyzstan's 10,000 cases per 1 million, followed by Yemen with 33,092.

Global life expectancy is back to pre-pandemic levels