The United States is in the midst of the second biggest measles outbreak since the highly contagious illness was officially wiped out in 2000.
As of last week, about 560 cases had been reported to the U.S. Centers for Disease Control and Prevention. Thats the highest since 2014, when there were 667 cases. In recent years, the case count has fallen as low 86 in 2016.
The current cases come from 20 states, although not Pennsylvania. It takes three or more cases in close proximity to be considered an outbreak. Under that standard, outbreaks are occurring in five states, including New York and New Jersey.
As of 2000, measles hasnt existed on its own in the United States, meaning all U.S. cases stemmed from someone becoming infected in a foreign country.
The current outbreak is being attributed to the anti-vaccine movement and pockets of people who dont allow their children to be vaccinated for religious reasons.
Doctors say a 95 percent immunization rate can protect schools and communities from measles outbreaks. With that many people vaccinated, the disease has no opportunity to gain a foothold. As a result, even people who cant receive vaccination for medical reasons are at low risk.
The overall vaccination rate among Pennsylvania school students puts them above the threshold for so-called herd immunity, according to the most recent immunization data from the Pennsylvania Department of Health.
But that doesnt mean Pennsylvania is without communities which, because of lower vaccination rates, are vulnerable to outbreaks.
In Lancaster County, for example, nearly 10 percent of students have obtained an exemption from common childhood vaccines, according to a recent LancasterOnline editorial which called on state lawmakers to ban non-medical exemptions.
Statewide, 96.8 percent of Pennsylvania kindergartners had two doses of the MMR vaccine during the 2017-2018 school year. The MMR vaccine protects against measles as well as mumps and rubella, also known as German measles.
Those figures include public as well as private schools.
Among seventh-graders, 97 percent had the required doses of MMR, according to the health department.
Pennsylvania children can be exempt from having the vaccine for religious, philosophical or medical reasons.
According to the health department, 123,377 children were enrolled in kindergarten in 2017-2018. Among them, 559 had received medical exemptions, 1,371 had received religious exemptions and 1,526 had received philosophical exemptions.
Also, 2,641 had been enrolled provisionally, meaning they had provided assurances they were in the process of getting the required vaccines.
Eighty-eight kindergartners were denied admission to school because they lacked required vaccines, according to the health department. Among seventh-graders, 105 were denied because they lacked required vaccines.
People who arent vaccinated have high odds of becoming infected if they are around someone carrying measles.
The largest outbreak is taking place in New York City and is believed to have originated with people who traveled to Israel.
An outbreak in Michigan is being attributed to someone who traveled there from New York.
Measles involves a high fever, cough and a rash. Some people, however, come down with complications that can be fatal or cause permanent damage. About one in ten people who get measles come down with ear infections, and roughly one in 20 develop pneumonia, according to the CDC. About one in 1,000 children who get measles develop a swelling of the brain which can result in deafness or intellectual disability.
About one in four people who get measles will need to be hospitalized, according to the CDC.
About one or two per thousand children who get measles will die from it, according to the CDC.