Rules for chemical formulas (Back to search) 1  Enter a sequence of element symbols followed by numbers to specify the amounts of desired elements (e.g., C6H6). 2  Use correct case for element symbols. 3  Elements may be in any order.  If only one of a given atom is desired, you may omit the number after the element symbol.
Half of all varicella zoster cases occur in children between the ages of 5 and 9. It has been estimated that, before the chickenpox vaccine was introduced in the U.S. in 1995, only 10 percent of Americans over the age of 15 had never had chickenpox.
What Is the Chickenpox Vaccine? The chickenpox vaccine is a shot that can protect nearly anyone who receives the vaccine from catching chickenpox. It's also called the varicella vaccine, because chickenpox is caused by the varicella-zoster virus. The vaccine is made from a live but weakened, or attenuated, virus. Viruses that have been attenuated are less virulent than viruses that are not.