Ninth-graders must get vaccinated against chickenpox or prove that they’ve had the disease, but many parents don’t know that, school nurses say.

And if parents don’t meet the requirement, their children could be barred from school.

“It’s a public-health safety concern,” said Lewiston Superintendent Leon Levesque.

In 2002, Maine adopted a rule that required all schoolchildren to be vaccinated against chickenpox by 2007. The law is being phased in over five years. Kindergartners and first-graders were required to get the shot this past fall. Students in kindergarten, first, second and ninth grades will have to be vaccinated this coming fall.

Since it became available in the United States in 1995, many doctors have added the chickenpox vaccine to the list of shots they routinely give to babies.

But next year’s ninth-graders were already preschoolers when the vaccine became available. Many of them had chickenpox when they were younger. Others never got the disease, and were never vaccinated against it.

School nurses across the state have tried to notify parents about the new requirement for their teenagers. In Lewiston, officials have sent letters home with the nearly 400 incoming freshmen and have started calling parents individually.

Cathy Liguori, a nurse for Lewiston High School, will not get the ninth-graders’ records until later this summer, she did not yet know how many students have had chickenpox or the shot. But she’s worried that the number is low.

Like many other school systems, Lewiston is planning to offer the shots at its school-based health clinic. Parents can also have their children vaccinated by their family physicians.

Students who have already had chickenpox won’t need to get the shot, but they will have to prove they have had the disease. Lewiston High School will accept documentation from family physicians. If a child didn’t see a doctor, the school will accept a doctor’s notation made later in the child’s medical records. It will also accept a blood test showing immunity.

Children will be exempt if they have a medical reason or if their parents are religiously or philosophically opposed.

Under state law, parents have 90 days from the start of school to get their child vaccinated or show why they haven’t. If parents don’t meet the requirement, their child could be barred from school.

Chickenpox is a highly infectious disease that causes a rash and fever. Of the 4 million people who get it every year, 11,000 are hospitalized and 100 die. According to the Centers for Disease Control, children who catch chickenpox can develop serious complications, including pneumonia and staph infections. Children with compromised immune systems, those who are taking steroids for asthma or who are HIV positive, are at the greatest risk.

The shot is not 100 percent effective, but officials say the disease is much less severe in the 10 percent to 20 percent of vaccinated people who get chickenpox.

According to the CDC, more than 20 states now require children to get the shot before they enter elementary school.

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