The varicella vaccine is recommended in many parts of the world for children, to protect them against chickenpox.
New research shows the important treatment also has another benefit; it reduces the risk of shingles in children. Shingles is an extremely painful rash that can occur in children over two years old.
The new study shows that only 38 per 100,000 children vaccinated against chickenpox developed shingles per year, compared with 170 per 100,000 unvaccinated children.
Shingles infection rates dropped even lower in children who received both doses of the chickenpox vaccine, compared to children who only received the first dose.
Vaccination levels on the rise
Chicken Pox causes fever and a spotty rash. It is highly uncomfortable but not highly dangerous in children.
However, even after recovery, the varicella virus remains latent in a person's nerve roots and can reactivate to cause shingles. This usually happens decades later and the consequences can be very severe including long-term nerve pain or vision loss.
The disease affects up to a third of people who had chickenpox as children according to the Centers for Disease Control and Prevention (CDC).
According to recent National Immunization Survey data, about 91 percent of children are vaccinated in the U.S. Like many vaccinations, the chickenpox shot is made up of live attenuated (weakened) varicella virus.
Medical records analyzed for shingle statistics
“The virus has been altered so the vaccine rarely causes symptoms, but once you’ve been immunized and after the natural infection, you carry the virus in your neurons for the rest of your life,” explains Anne A. Gershon, a professor of pediatric infectious disease at Columbia University.
To complete the recent research, medical records from nearly 6.4 million children (ranging from newborns to 17-year-olds) who received care at six health care organizations in the West, Northwest and Midwest from 2003 to 2014 were analysed.
The children's records were examined from birth until they left the pediatric system at aged 18 (so any shingles infections after age 18 were not included).
Vaccine clearly reduces shingle risk
The results show that half the children were vaccinated for at least part of the full study period; the other half were not. One dose of the chickenpox vaccine reduced shingles infection by 78 percent — except in young toddlers.
Interestingly, shingles rates were much higher in vaccinated one-year-olds than unvaccinated ones, but this high-risk period disappeared when the children turned two.
The risk period may be related to the intense period of immune defense occurring at that age. The researchers are quick to note that, they do not recommend delaying the vaccination past the recommended age of one. Doing so may place the child at risk of contracting the disease from the ‘wild’ and then, pass it onto their infants that are too young to be vaccinated.
Even children that aren’t vaccinated from chickenpox are benefiting, due to a phenomenon known as ‘herd immunity’. This refers to the inability of diseases to travel through a community due to high vaccination rates.
In this case, herd immunity protects unvaccinated children from both chickenpox and then, by default shingles, which can only be developed once the disease is dormant in the nerves.
However, it does not protect unvaccinated children as they grow older and become more susceptible to chickenpox from other sources.