PHILADELPHIA (WPVI) -- Since early December, there have been more than 130 confirmed cases of measles in 15 states, 102 of them since January 1st.
The single cases in Pennsylvania and Delaware are not related to the outbreak last month at Disneyland in California.
But the fast spread of the contagious disease is reigniting the vaccine debate.
Christine McGuire, mother of twins, says fears that the vaccine causes autism need to be put to rest.
"I have twins. They were both vaccinated on the same day, with the same batch, at the same time. One's on the spectrum, one's not on the spectrum," McGuire said.
Measles was once eradicated in the US thanks to the vaccine, but worldwide, there are still millions of cases each year.
It becomes a problem here when parents don't vaccinate their children.
"Measles is literally a plane ride away, when it gets into communities like the United Stoats, in certain pockets where a lot of people are unimmunized then it has a chance to spread," Dr. Anne Schuchat of the National Center for Immunization & Respiratory Diseases said.
The virus, which spreads through droplets in the air, can be spread easily.
"If someone's in a room infected with measles, in that room, you can get with measles from the air for roughly three hours after they've left," Dr. John Goldman, infectious disease specialist, said during a media call-in, hosted by the Pennsylvania Medical Society.
That's why health officials are urging more parents to have their kids vaccinated.
During the call-in, Pennsylvania's acting physician general, Dr. Rachel Levine, said vaccination rates aren't as good as they could be.
In the state, only 87% of kindergartners are vaccinated. That is one of the worst rates in the nation.
By 7th grade, that rate rises to 95%.
In Cumberland County, the site of Pennsylvania's measles case, kindergarten vaccinations are just 85%.
However, doctors say kids should be fully vaccinated sooner to get the best protection and will help protect kids under 12 months old, who are too young to get the vaccine.
Dr. Tibisay Villalobos, a pediatric infectious disease specialist in the Lehigh Valley, says one obstacle to better vaccination rates is the state-by-state patchwork of school immunization regulations.
"We need to unify those," Dr. Villalobos says.
In Pennsylvania, parents can get exemptions from vaccinations if: it would endanger the health of the child, or for religious or strong moral or ethical objections.
During the 2013-14 season, there were 1,444 medical exemptions, 2,119 religious exemptions, and 2,351 exemptions for philosophical reasons in the Keystone State.
New Jersey doesn't have a philosophical exemption per se, however, a court ruling said parents didn't have to defend their grounds if they claimed a religious exemption.
After that, the number of religious exemptions rose sharply.
The doctors on the Medical Society call-in agreed on the need for new and better ways to communicate with parents about the need for vaccinations, and the consequences of not getting the shots, or even delaying some.
Dr. Villalobos said if a second dose is delayed, children are only partially immunized and vulnerable to diseases.
Another concern some parents have had is about reports of seizures after vaccine shots.
Dr. Villalobos says that when the measles/mumps/rubella shot was combined with the chicken pox (varicella) vaccine, there were more children getting fevers and fever-related seizures right afterward.
However, those didn't cause permanent harm, and the chicken pox vaccine is now a separate shot again.
All children uninsured, under-insured, or without proper identification can be vaccinated for free under the federal Vaccines for Children program.
For information, call 1-877-PA-HEALTH.