After the worst month for measles in more than two decades, public health officials gathered at the Johns Hopkins University on Monday to talk about ways to prevent 2015 from becoming the worst year for the disease.
Local, state and federal officials spoke of boosting vaccination rates against the highly contagious and potentially deadly disease by making it more difficult for parents to claim exemptions for religious or personal beliefs, by reaching out to those who refuse vaccinations and by better tracking of children who are not vaccinated.
The symposium comes amid concern about the outbreak that officials believe spread from Disneyland in California to seven states, Canada and Mexico. The U.S. Centers for Disease Control and Prevention on Monday reported more than 120 cases in the United States this year, most of them linked to Disneyland.
Public health officials blame the outbreak on the refusal of some parents to vaccinate their children. Measles was eradicated in the United States in 2000, but in recent years the number of infections has crept up, to a high of more than 600 last year.
"Measles is due to a failure to vaccinate," said Jane Seward, deputy director of the division of viral diseases at the CDC.
There have been no recent cases reported in Maryland, where the vaccination rate among school-aged children is more than 97 percent, and Baltimore has not seen a case in the last decade. Still, state officials plan to better count the rate among preschoolers, who are at the age when the vaccine and booster are recommended.
Daniel Salmon, deputy director of the Institute for Vaccine Safety at the Johns Hopkins Bloomberg School of Public Health, said the varying vaccination rates across the country correlate to state laws. At the permissive end of the spectrum are states such as California, which allow religious and philosophical exemptions. At the more restrictive end are West Virginia and Mississippi, which allow only medical exemptions.
Maryland allows religious and medical exemptions. For a religious exemption, parents must sign a form; for a medical exemption, they must present a note from a doctor.
State lawmakers have discussed the law privately, but no new legislation has been introduced. A spokeswoman for Gov. Larry Hogan said the governor "supports vaccinations as a safe and proven way to protect our children from common and deadly diseases."
"Parents and caretakers are the first line of defense for keeping kids safe and healthy," spokeswoman Erin Montgomery said.
Salmon warned against moving too aggressively to tighten rules, which he said could alienate parents who are fearful of the vaccine or distrustful of doctors or the government.
He cited the guidance of the American Academy of Pediatrics, which said doctors work to change minds by explaining the science, or their experiences with other patients and their own children.
"We need to be careful of a backlash," Salmon said, warning that it could harden parents' beliefs and push them to the small cadre of medical providers who don't encourage vaccination. He said more study is needed to determine how to intervene most effectively.
Dr. Leana Wen, Baltimore's health commissioner, and leaders from 15 Baltimore-area health departments, medical institutions and associations unveiled a statement of support for vaccination Monday.
They called the measles vaccination approved in 1964 "one of the safest and most successful medical advancements in history," and warned that "the Disneyland outbreak raises the real risk that measles may come roaring back."
The health leaders, who included doctors from Hopkins, University of Maryland, Sinai, Saint Agnes, Franklin Square, Greater Baltimore Medical Center, Mercy and Harbor hospitals, said the anti-vaccination movement puts children risk. They called vaccines "more than an individual choice; they are an obligation to one another."
They urged parents to turn to physicians and scientists for guidance in making their medical decisions.
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"We can address misinformation and myths about vaccination with science and facts," they said.
Before the measles vaccine was approved in 1964, the United States saw up to 4 million cases per year in children, nearly 50,000 hospitalizations and up to 500 deaths.
After the vaccine was introduced, deaths fell by 75 percent. And now that 92 percent of children get the combination measles, mumps and rubella vaccine, there hasn't been a death in the United States since 2003.
Dr. Neal Halsey, director of the Institute for Vaccine Safety at the Bloomberg school, said the vaccine is 93 percent effective rate after one dose, recommended at 12 to 15 months, and 97 percent effective after two.
"It's not perfect, but it's an excellent vaccine," he said.