![A vial of the measles, mumps, and rubella (MMR) vaccine.](https://media.guim.co.uk/6cead1c6fc9f0f7767583ce718e35c6078aeb1db/0_52_5388_3235/1000.jpg)
Around 20,000 people may have been exposed to measles at a large religious event in Kentucky, the federal Centers for Disease Control and Prevention and said.
In a statement to the Guardian, the CDC said it was “aware of a confirmed case of measles in an unvaccinated and contagious individual who attended a large religious gathering in Kentucky on 17 and 18 February.
“Large numbers of people that attended the gathering from across Kentucky and from other states and countries may have been exposed.
“An estimated 20,000 people attended the gathering on the days that the patient attended. The Kentucky department for public health is actively working with CDC and clinicians to help identify if there are additional cases.”
The event was a multi-week religious gathering held by Asbury University in Wilmore, Kentucky. The “revival”, which began on campus on 8 February, saw between 10,000 and 20,000 people descend on the 6,000-person town. The event was moved off campus around two weeks later.
On 24 February, Asbury University released a statement saying state officials confirmed a case of measles in a Jessamine county resident. According to the university, the resident was unvaccinated and had attended the revival on 18 February.
The university urged those not fully vaccinated against measles who attended services on 18 February to quarantine according to CDC guidelines.
“Attendees who are unvaccinated are encouraged to quarantine for 21 days and to seek immunization with the measles vaccine, which is safe and effective,” said Steven Stack, commissioner of the Kentucky department of public health.
The CDC told the Guardian: “To prevent further spread, CDC recommends that clinicians continue to be on high alert for measles symptoms among those who may have attended this event, as well as symptoms in unvaccinated international travelers.”
Measles is highly contagious and can be dangerous, particularly for babies and young children. The virus can stay in the air for up to two hours after an infected person was there.
According to the CDC, the disease is so contagious that if one person has it, up to 90% of people close to the individual will become infected if they are not protected. Symptoms include high fever, cough, runny nose and red, watery eyes.
Two doses of the MMR vaccine are about 97% effective at preventing measles. One dose is about 93% effective, the CDC says.
WKYT reported that students attending Asbury University are required to receive the two-dose MMR (measles, mumps and rubella) vaccine.
The case is the third of measles confirmed in Kentucky in the last three months. According to state health and family services authorities, the first case was reported in December 2022 and was linked to another measles outbreak in Ohio.
The second case, which had no known exposures or connections to the Ohio outbreak, was reported in January. Neither presented a public health threat, the state government said.