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.
Vaccination is the best way to prevent chickenpox. A chickenpox vaccine has been available in the U.S. since 1995 and is easy to get from a doctor or a public health clinic.The chickenpox vaccine is very effective at preventing the disease -- between 70% and 90% of people who get vaccinated will be completely immune to chickenpox.wo doses of the vaccine should be given at least four weeks apart. If you've never had chickenpox or been vaccinated and you are exposed to chickenpox, being vaccinated right away will greatly reduce your risk of getting sick.