Researchers say children with allergies to vaccines can still be immunized safely.

Johns Hopkins researchers said that high-risk children can be given allergen-free forms of vaccines.

The children will need close observation by a doctor for several hours after being immunized, researchers said. They can also be treated with anti-allergy medications before getting the vaccine.

Doctors said it's even possible to withhold a vaccine if a blood test shows a child has developed an immunity to the condition.