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.
Cowpox was used as a vaccine for smallpox in 1798. The first vaccination was a traditional cure in Turkey whereas babies were exposed to animals turd, upon discovering the fa â¦ ct that these babies became immune to diseases scientists concluded the way to methodical vaccination.It is against small pox and is discovered by E. Jenner in 1798.he first vaccination was a traditional cure in Turkey whereas babies were exposed to animals turd, upon discovering the fa â¦ ct that these babies became immune to diseases scientists concluded the way to methodical vaccination. It is against small pox and is discovered by E. Jenner in 1798.