EDITOR’S NOTE: This story was updated on April 1.

MOUNT VERNON — On March 29, a laboratory confirmed that two new cases of measles were found in international travelers in Knox County. These individuals are isolated and symptoms are being monitored throughout their isolation periods.

Knox Public Health (KPH) has been working with the individuals since contact tracing began and they have been in quarantine. No additional close contacts were identified as a result of the two positive cases.

One measles case was confirmed in Knox County on March 24. 

A traveling international adult contracted measles and is no longer infectious, according to a Knox Public Health press release. 

The state health agency is working with Knox Public Health (KPH) to follow up on contacts and promote opportunities for vaccination. KPH is also working with the individual and their healthcare provider to identify contacts, according to the release.

The MMR vaccine guards against three diseases (measles, mumps and rubella) with 97% effectiveness, KPH epidemiologist David Hatley said via email. The two-dose vaccine is given to adolescents one year to 15 months of age, second dose when they’re four to six years old. 

Quick facts of measles and the MMR vaccine

  • Incredibly safe and effective vaccine with hundreds of millions of doses given.
  • Common mild reactions: fever, mild rash
  • Serious adverse events extremely rare (1 per million doses)
  • No link to autism
  • To achieve herd immunity you need a 95% coverage needed to prevent community transmission

Measles is one of the most transmissible viral diseases we know, Hatley said. It’s extremely contagious when it comes to human-to-human transmission, he said.

“If a susceptible person is exposed to an infected individual, there’s about a 90% chance they will contract the virus,” Hatley said. “Measles spreads via respiratory droplets and can remain airborne or viable on surfaces for up to two hours after the infected person has left the area, meaning even brief encounters or shared airspace can result in transmission.

“In an unvaccinated population, for every one person who contracts measles, an estimated 12 to 18 other people may also become infected,” Hatley said. 

In the last few years, Hatley said, the measles vaccination rate in Knox County has declined.

In Knox County, the kindergarten MMR vaccination rate has declined over the past five years, dropping from approximately 90% to 84% this year.