What you need to know about the chicken pox vaccine

Somewhere between 12 and 15 months, your toddler’s doctor will likely recommend vaccinating your child against varicella — more commonly known as chicken pox. While this vaccine is still optional, for many families it’s become part of the routine vaccination schedule, often administered with the measles, mumps and rubella vaccines. Almost nine out of 10 times, the vaccine prevents kids who are exposed to chicken pox from catching the extremely contagious infection.

This particular shot wasn’t available when you were a child: it was only introduced in Canada in 1998. But between 2000 and 2007, provinces and territories started picking up the tab for one dose. Today, six also cover the recommended second dose (given either at 18 months or four to six years, depending on where you live).

You may remember your own childhood bout with chicken pox as a rite of passage. Maybe it wasn’t that big of a deal, or maybe you were totally miserable and covered in spots that ended up scarring. Some parents theorize that if they weren’t vaccinated, why should they subject their kid to an optional shot? But it’s worth reconsidering. Children with a typical case of chicken pox break out in 300 to 500 itchy blisters, and may come down with a fever, headache, sore throat and tummy ache.

Taking a week off work to care for a sick kid is no small matter for most working parents. Chicken pox is contagious from 48 hours before the rash appears until all the pox are crusted over — usually about five to seven days. Beware that chicken pox can also appear in multiple waves. Plus, if your vaccinated kid does end up catching it, his or her case will likely be much more mild (less than 50 pox). The shot sharply reduces the odds of severe illness by 95 percent and other uncommon (but serious) complications.

“Before immunization, about 1,700 to 2,200 kids per year across the country would be admitted to hospital with chicken pox,” explains Joan Robinson, chair of the Canadian Paediatric Society’s Infectious Diseases and Immunization Committee. (Those numbers have since dropped dramatically — by 2008, chicken-pox-related hospitalizations had declined by 88 percent in provinces where widespread immunization was first adopted.) Another rationale for vaccinating? It cuts down on transmission of the virus to vulnerable individuals, like pregnant women and newborns. (Infants are far more prone to very severe infection, and the vaccine isn’t effective for them, because of their immature immune systems.)

The most common side effect of the vaccine is a short-lived swelling and soreness around the spot where the needle went in. The Canadian Paediatric Society suggests a dose of acetaminophen to ease symptoms. (This is controversial, however — some doctors caution against giving acetaminophen or ibuprofen because some research has hinted it may make the vaccine less effective.) There’s also a tiny risk of a serious allergic reaction to one of the vaccine ingredients, such as the antibiotic neomycin, “but that’s very treatable,” Robinson reassures.

Matt James and his wife didn’t debate vaccinating their daughters, now six and 10, against varicella as toddlers. “I’m in favour of doing what we need to do to make our kids the healthiest they can possibly be,” the Toronto dad says. His younger daughter has avoided getting chicken pox entirely, despite being exposed. And while his older daughter did catch it, James is convinced her symptoms would’ve been much worse had she not been vaccinated. “We didn’t even pick up on it,” he says. “We sent her to school and one of the teachers said, ‘she’s got chicken pox.’ She wasn’t very itchy, and the bumps were just tiny specks.”

A version of this article appeared in our February 2013 issue with the headline "The chicken pox shot," p. 44.

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