Universal vaccination against chickenpox with an attenuated, live vaccine began about 25 years ago in the United States. At the time of its release several unanswered questions about the vaccinemade some hesitant to recommend it. How long would protection last following a single dose? Would a booster dose be needed? Adults tend to have an increased risk of adverse outcomes with varicella as compared to children. Would previously vaccinated persons start coming down with varicella as adults?
Pre-vaccine in the US, only about 10% of the 4 million cases per year of varicella occurred in adults. On average, there were about 140 deaths from chickenpox annually but 50% of the deaths were in persons over the age of 18 years Risk of hospitalization was higher in adults as well.
Concerns over the impact of the vaccine on adult shingles risk were raised by some experts. Varicella is in the herpes virus family and like HSV may live forever in a human following the initial infection. The varicella virus can take up residence in a sensory nerve ganglion and when reactivated causes herpes zoster or shingles. Would the live but attenuated varicella vaccine virus be more or less likely to result in shingles outbreaks in the future?
The answer wasn't known 25 years ago but it is today. Studies examining the virus type in a shingles outbreak and vaccine virus and wild virus can be differentiated as the etiology of the outbreak.
Try a quick 2-question quiz on the impact of the varicella vaccine on herpes zoster.