The 2013 Childhood National Immunization Coverage Survey released Tuesday found that 89 per cent of two-year-olds had received the recommended immunization against measles, mumps and rubella, while 77 per cent had all their shots for diphtheria, pertussis (whooping cough) and tetanus.
Uptake of the polio vaccine was 91 per cent and 73 per cent of kids had been inoculated against chickenpox, the survey of 5,500 parents and guardians found.
The survey also collected data on immunization against the human papilloma virus for girls aged 12 to 14 and 17. The HPV vaccination rate was 72 per cent for 12- to 14-year-olds and 64 per cent for 17-year-olds. HPV is a sexually transmitted infection that causes most cervical cancers, as well as some other genital cancers in both women and men.
The survey also found that a small proportion of Canadian children — 1.5 per cent — had never received immunizations of any kind.
"These are really sub-optimal," Dr. Joan Robinson, an infectious disease specialist at Stollery Children's Hospital in Edmonton, said of the overall vaccination rates.
"What we would like to see is about 90 per cent uptake for all of the vaccines.... That's the rate that you usually need to get decent herd immunity."
Herd immunity occurs when enough individuals in a given population have immunity through vaccination or previous exposure, which confers protection to those who aren't immunized by preventing a contagious bacteria or virus from setting up a chain of infection.
"But for measles, because it's so contagious, we think that even 95 per cent immunization might be what (we) would need to prevent spread if a case is introduced into a community," said Robinson.
"Very few" children, she said, can't be vaccinated — typically because of a suppressed immune system from being on chemotherapy or drugs that prevent organ rejection, for instance. Having a 90 per cent coverage rate usually means such children benefit from herd immunity.
"But almost all of the children can be immunized and should be immunized."
Dr. Gregory Taylor, Canada's chief public health officer, said that with 5,500 respondents the survey about children's vaccination status is the largest ever commissioned by the Public Health Agency of Canada (PHAC). The previous survey in 2011 involved 400 parents and guardians.
"This is a huge amount of information," he said Tuesday. "So the numbers that have gone out so far are preliminary. They're highlights. We're going to spend a great deal of time in the next little while doing further analysis of the data."
That analysis will look at vaccination data for seven-year-olds, which was also collected by Statistics Canada for PHAC.
Besides compiling immunization rates, the survey also asked respondents questions aimed at assessing their knowledge about vaccines and attitudes toward their use — information Taylor called "really interesting."
Most respondents agreed that childhood vaccines are important for children's health (97 per cent); that childhood vaccines are effective (97 per cent); and that vaccines are safe (95 per cent).
"But on the flip side, we've got 70 per cent of parents who are concerned about potential side-effects (and) 37 per cent believe a vaccine can give you a serious case of the disease it was meant to prevent, which is just not true," he said.
"And 17 per cent believe that alternative practices such as homeopathy, chiropractic, etcetera, can eliminate the need for vaccinations. Seventeen per cent! That's just not true — there are no substitutes for vaccines."
Taylor said such information can help inform public health efforts to improve childhood vaccination rates in Canada, which he said are good but acknowledged could be better.
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