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Chickenpox is no reason to keep the kids at home

Even though pediatricians have said for years that children with mild chickenpox are well enough to attend school or daycare, kids continue to be banned from those facilities for five days in what some say amounts to scare over science.

Not only are these exclusion policies hard for children who unnecessarily miss school, but they are also difficult for parents who must take time off work or hire care, said Noni MacDonald, a pediatric infectious disease specialist based in Halifax.

"One should be encouraging school boards and public health to have a policy that's evidence-based, and not give in to scare tactics and complaints from parents who are ignorant about what the real risks are," said Dr. MacDonald, principal author of the Canadian Paediatric Society's statement on chickenpox and exclusion policies.

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Since 1994, the society has recommended that the only children with chickenpox who should be excluded are those who are feverish or so ill that they require more care than can be provided by school or daycare personnel.

The recommendation is based on epidemiological studies and virology data, which show that the exclusion of children from school or daycare for five days once the chickenpox rash has developed is too late to prevent exposure of fellow classmates.

"We had so many kids out of school and it was ridiculous," Dr. MacDonald said in a telephone interview. "Kids were missing school who were well enough to go to gymnastics class. It was just a farce."

Policies on chickenpox vary greatly across Canada, differing by school board and public health unit.

In Manitoba and Alberta, children are not excluded and can attend school with mild chickenpox as long as they feel well enough to participate normally in all activities. British Columbia's new draft policy – not yet posted on its website – is more ambiguous.

"We are silent on whether a child should be excluded," said Monika Naus, director of the immunization program at the BC Centre for Disease Control, in a telephone interview. "But we state that if a child is excluded, they should come back in when they are well enough to partake in usual activities and when the lesions have crusted over, which is usually day 5."

Toronto Public Health has had both experiences: It dropped the exclusion policy a decade ago, but then reinstated the five-day exclusion several years later, in part because of pressure from schools.

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"I do agree with what the CPS [Canadian Paediatric Society] is saying, for kids with mild disease there really isn't any point to exclusion," said Rita Shahin, associate medical officer of health for Toronto Public Health. "It's a lot easier for a school to say 'five days' because then it's something that's very easy to count as opposed to how many spots does a kid have."

Dr. Shahin said that once things settle down with H1N1, Toronto Public Health will review its exclusion policy, which could include dropping the five-day exclusion policy.

Chickenpox is a highly contagious illness caused by the varicella zoster virus. The vast majority of cases – about 90 per cent – occur before a child turns 12. It is characterized by a rash of raised red blisters that are extremely itchy. Some children have only a few blisters while others can have as many as 500.

Breakthrough chickenpox – cases in which the child has acquired the disease despite vaccination – usually results in milder illnesses, typically defined as those with fewer than 50 spots.

"The reason why the Canadian Paediatric Society thinks that children should not be excluded from school with mild chickenpox is because they are actually contagious for one day before they break out in the rash, so most of the time the other children have been exposed anyway," said Joan Robinson, a member of the society's infectious diseases and immunization committee. "So then it seems a bit silly to keep them home from school for several days in order to not infect any one when the other children have all been exposed." She pointed out that most children are vaccinated against the disease.

Those with chickenpox are infectious from two days before the rash appears until roughly five days after, when all the blisters have fully crusted over.

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While the vaccine – typically provided to children after their first birthday – is funded by provincial health plans, it is not mandatory. But pediatricians, such as Dr. MacDonald, stress the need for children to be vaccinated.

And, she said, if a physician determines a child is healthy enough to return to the classroom, that should be heard.

"If your doctor says you are ready to go back, you are ready to go back," Dr. MacDonald said. "It's not fair to the child to be caught in the middle of this."

One dose or two?

Canada offers one shot, the United States offers two. The difference in approach amounts to controlling a disease compared with eradicating it.

Canada's approach

The chickenpox vaccine is typically given after a baby's first birthday but before the child is 15 months old. Despite vaccination, a small percentage of children will catch the disease, usually in its more mild form. The effectiveness of a single shot of vaccine ranges from 70 per cent to 90 per cent.

The National Advisory Committee on Immunization says it is reviewing evidence suggesting that a second dose of vaccine may be necessary for optimal immunity. It is expected to provide a revised statement early in the new year, according to Public Health Agency of Canada spokeswoman Caroline Grondin.

The U.S. approach

Babies get the first dose of vaccine between 12 and 15 months of age, then a booster, usually from ages 4 to 6. But the booster can be administered earlier as long as the interval between the first and second dose is greater than three months, according to recommendations of the Advisory Committee on Immunization Practices.

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