Chicken pox is an acute infectious disease accompanied by fever and a characteristic vesicular rash on the skin. Children up to ten years of age are the main victims, but after infection, immunity is guaranteed for life. The causative agent is a filterable virus Varicella zoster, which is transmitted from an infected person to a healthy one mainly by means of air droplets (fine sprays of saliva during coughing or sneezing). Symptoms include a rise in temperature and a skin rash which becomes blisters which erupt, and resultant considerable and uncomfortable irritation.
While generations of children have been infected with chickenpox and survived with little more than a scar, a small percentage will develop serious complications such as pneumonia, bacterial infections and arthritis.
According to the US Centers for Disease Control and Prevention (CDC), more than 90% of infections, two-thirds of varicella-related hospitalizations and nearly half of varicella-related deaths occur in children. The incidence of disease had been highest among children ages 5 to 9 in the past but now occurs most frequently in children ages 1 to 4.
Prior to the universal varicella vaccination program, 95% of adults experienced natural chickenpox (usually as school aged children)—these cases were usually benign and resulted in long term immunity. This high percentage of individuals having long term immunity has been compromised by mass vaccination of children which provides at best 70 to 90% immunity that is temporary and of unknown duration—shifting chickenpox to a more vulnerable adult population where chickenpox carries 20 times more risk of death and 15 times more risk of hospitalization compared to children. Add to this the adverse effects of both the chickenpox and shingles vaccines as well as the potential for increased risk of shingles for an estimated 30 to 50 years among adults. The Universal Varicella (Chickenpox) Vaccination Program now requires booster vaccines; however, these are less effective than the natural immunity that existed in communities prior to licensure of the varicella vaccine.