What is chicken pox, and what are the risks of the disease?page up: Childhood Vaccinations FAQnext page: 3i.3 What is Herpes Zoster?
An estimated 3.7 million Americans are affected by chickenpox each year, with more than 90% of the cases occurring in persons under 15 years of age. 33% of cases are estimated to occur in children ages 1 to 4, and 44% in children ages 5 to 9 (estimates from January 28, 1994 FDA announcement). In tropical regions, chicken pox is less common, and many people may reach adulthood without immunity (adult immigrants from tropical to temperate regions may therefore be at risk). I do not have data on how varicella incidence has been affected by the availability of the vaccine, but vaccine coverage is still (as of 1999) fairly low for this particular vaccine.
