For one thing, the vaccine is weaker than a major test version. It is aiming for 95 percent by age 5. It is unclear whether patients are immune for life or need a booster dose. Because chickenpox is often more serious in adulthood, some parents in the past tried to expose their children to the disease while they were young. Seward said the vaccine may eventually prove useful also in fighting shingles, a disease caused by the same virus as chickenpox.
Shingles causes a painful skin rash and sometimes chronic pain.