Measles outbreak: a timeline
The vaccination rate for a Liberty middle school where a student exposed others to measles is relatively high, but more than a dozen students are being held out of classes because they haven't had the shot.
That's according to data released by Liberty Public Schools 53 in response to an open records request by The Star.
The data showed that only 13 of the 791 students at South Valley Middle School opted out of the measles-mumps-rubella vaccine; an immunization rate of about 98.4 percent. Eleven students have religious exemptions from the vaccination and two have medical exemptions.
The district had previously declined The Star's request for the school's vaccination rate, citing student privacy.
The measles case at South Valley Middle School is one of 10 that the Kansas City Health Department is tracking in an outbreak that has exposed people throughout the metro and in Iowa, Minnesota and Wisconsin. A separate outbreak that started in a Johnson County day care last month has sickened 20 Kansans so far — the most measles cases in that state since 1990.
Health departments on both sides of the state line have released lists of public places where people with measles might have exposed others. People who were at those places at those times are advised to monitor themselves for symptoms for 21 days, especially if they haven't been vaccinated. The early symptoms are high fever, cough and runny nose, followed by a telltale red rash.
Those who suspect they have measles are asked not to leave their house except to seek medical care and even then to call ahead so that doctors and hospitals can arrange the separate them from other patients.
The Missouri outbreak also includes a student at Warren Hills Elementary School and Liberty North High School, but health officials say no one was exposed at those locations because the students in question were not at school during the period of contagiousness.
District spokesman Dallas Ackerman said there have been no new cases of measles reported at South Valley Middle School since the April 18 exposure and all 13 students are being held out of class under Missouri's vaccine exclusion policy.
Students in Missouri and Kansas can get religious exemptions from vaccination with a note from a parent or guardian. To get a medical exemption, they need a note from a licensed physician. But during times of infectious disease exposure they're held out of school until the danger passes.
Chip Cohlmia, an infectious disease epidemiologist with the Jackson County Health Department, said there are several medical conditions and treatments that prevent people from being vaccinated because they weaken their immune system and others can't be vaccinated because they are allergic to components of the vaccine.
“It is unfortunate to have individuals excluded (from school), however at the same time I’d say it’s really necessary to control the spread of disease, especially if you’re looking at somebody who is already immuno-compromised," Cohlmia said. "Having an individual who is already in that state get the disease is extremely problematic.”
South Valley Middle School's vaccination rate is well above the 90 to 95 percent threshold experts say is needed for herd immunity to prevent the spread of disease. But that threshold is based on a general population mixing randomly, not a self-contained environment like a school.
Cohlmia said more than 90 percent of people who aren't vaccinated will get measles if they're exposed to it and it's so contagious that people don't even have to be in the same room at the same time as someone who has it to pick it up.
“The virus can survive on surfaces up to two hours after the person leaves,” Cohlmia said.
Two doses of the MMR vaccine is about 97 percent effective at preventing the disease, though.
The Centers for Disease Control declared measles eliminated from the United States in 2000, but people still bring it back from other countries and spread it among U.S. residents who aren't vaccinated, including infants too young to get the shot.
Most people who get measles fully recover, but the disease can cause life-threatening complications like pneumonia and, more rarely, encephalitis.