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.
Jonas Salk created the first safe and effective vaccination for Polio in 1955. He also worked on the vaccine for Influenza type B. Polio, which has almost been eliminated du â¦ e to the successful vaccinations, affects the spinal chord and causes paralysis in 1/200 cases.