The Impact of Varicella Vaccination on Herpes Zoster in Children
Abstract & Commentary
By Hal B. Jenson, MD, FAAP, Professor of Pediatrics, Tufts University School of Medicine, and Chief Academic Officer, Baystate Medical Center, Springfield, MA, is Associate Editor for Infectious Disease Alert.
Dr. Jenson reports no financial relationships relevant to this field of study.
Synopsis: Varicella vaccine reduces the risk of herpes zoster 4-12-times among children < 10 years of age. When herpes zoster does occur among vaccine recipients, it is associated with less frequent and less severe pain.
Source: Civen R, et al. The incidence and clinical characteristics of herpes zoster among children and adolescents after implementation of varicella vaccination. Pediatr Infect Dis J. 2009;28:[Epub ahead of print].
A population-based telephone survey was conducted among residents < 20 years of age in Antelope Valley, CA, from 2000 through 2006. During this period, 459 evaluable cases of herpes zoster among persons < 20 years of age were reported. Of these cases, 154 (34%) were among children < 10 years of age and 305 (66%) were among persons 10-19 years of age. The median age was 12 years (range: 11 months-19 years), with 215 (47%) cases in males, 220 (48%) cases among white non-Hispanics, 156 (34%) among Hispanics, 51 (11%) among African-Americans, and 16 (3.5%) among Asians or American Indians.
Of the 154 cases among children < 10 years of age, 40 (26%) reported varicella vaccination alone, 81 (53%) reported varicella disease alone, 24 (15.5%) reported an unknown history of vaccination and/or disease, eight (5%) reported both vaccination and disease, and one (0.5%) denied a history of both.
Of the 305 cases among persons 10-19 years of age, six (2%) reported varicella vaccination alone, 245 (80%) reported varicella disease alone, 45 (15%) reported an unknown history of vaccination and/or disease, five (2%) reported both vaccination and disease, and four (1%) denied a history of both.
During this period, the incidence of herpes zoster among children < 10 years of age declined by 55%, from 42 cases in 2000 (74.8/100,000; 95% CI: 55.3-101.2) to 18 cases in 2006 (33.3/100,000; 95% CI: 20.9-52.8; p < 0.001). Children < 10 years of age with a history of varicella vaccination had a 4-12 times lower risk for developing herpes zoster compared with children with history of varicella disease. The incidence of herpes zoster among persons 10-19 years of age increased by 63%, from 35 cases in 2000 (59.5/100,000; 95% CI: 42.7-82.9) to 64 cases in 2006 (96.7/100,000; 95% CI: 75.7-123.6; p < 0.02).
Of the 459 cases of herpes zoster, 372 (81%) had complete clinical information. Most (82%) cases occurred among healthy children and adolescents. Only nine (2%) cases occurred among persons with underlying immunocompromised conditions, all with a history of varicella disease and no vaccination. The clinical characteristics among those with a history of varicella disease were similar between the two age groups, with the exception that persons 10-19 years of age were more likely to report presence of pain (87% vs. 77%; p = 0.02) and treatment with acyclovir (67% vs. 42%, p < 0.0001). Of cases of herpes zoster among children < 10 years of age, vaccinated children, compared to children with a history of varicella disease, were younger (median age: 5 years vs. 8 years), more likely to have herpes zoster rash located in the lumbar/sacral dermatomes (28% vs. 11%; p = 0.02), less likely to report pain (45% vs. 77%; p <0.001) and, when pain was reported, less likely to report intense pain (p = 0.03).
Commentary
This is the largest population-based study assessing the incidence and clinical characteristics of herpes zoster among children vaccinated with varicella vaccine. The decline in the incidence of herpes zoster among children < 10 years of age most likely reflects the impact of universal childhood varicella vaccination, which began in the United States in 1995. In 2006, a two-dose vaccination strategy was implemented, with the first dose at 15 months of age and a second dose at 4-6 years of age, with a minimum planned interval between doses of three months and an absolute minimum of 28 days to count as a second dose.
The basis for the increasing incidence of herpes zoster among children and adolescents 10-19 years of age is unclear, and may reflect improved reporting of cases. There is also a suggestion from other studies that universal varicella vaccination may actually increase the incidence of herpes zoster among persons who have had varicella disease because of less frequent immunologic boosting from exposure to wild-type varicella virus circulating in the community. If this phenomenon is occurring, it will eventually abate with continued universal vaccination, with the incidence of herpes zoster eventually falling below pre-vaccine levels.
Vaccinated children < 10 years of age reported less frequent and less intense pain with herpes zoster than those with a history of varicella disease. Vaccination was also associated with limited involvement of the rash to the lumbar/sacral dermatomes. This is an interesting anatomic association that has been reported previously between the site of varicella vaccination, which in young children is typically the anterolateral thigh, and the site of herpes zoster rash. Herpes zoster among unvaccinated children most often involves the thoracic dermatomes, which reflects the intensity of the centrally distributed varicella rash.
A population-based telephone survey was conducted among residents < 20 years of age in Antelope Valley, CA, from 2000 through 2006. During this period, 459 evaluable cases of herpes zoster among persons < 20 years of age were reported.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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