Via CBC News British Columbia: Vaccination rates too low for 'herd immunity' in most Vancouver-area schools, study finds. Excerpt:
Vaccination rates among kindergarteners in Vancouver-area schools are too low, in many cases, for the schools to benefit from "herd immunity," according to a new study by University of B.C. researchers.
Herd immunity occurs when enough people in a community are vaccinated that it's difficult for a disease to spread, offering protection to those unable to be vaccinated due to health conditions or age.
The study, published in Vaccine Reports, looked at how many kids were up-to-date with recommended vaccinations for measles, mumps, rubella, pertussis and other diseases in the 2013-14 school year in urban areas of the Vancouver Coastal Health Authority.
Rates varied widely by school and type of vaccine — from as low as 15 per cent up to 100 per cent compliance with recommended vaccinations.
The study found most schools don't have immunization rates of 90 per cent, which is generally needed for "herd immunity," said author Julie Bettinger, a researcher at UBC and the Vaccine Evaluation Centre of B.C. Children's Hospital.
"For parents … I would hope that it maybe shakes their complacency a little bit," she said.
"If I'm at a school where the coverage is coming in at 60 per cent, if someone brings measles into my school, my kid may not be protected if he's not gotten the vaccine."
Private schools lower, Richmond higher
The study was exploratory, prompted in part by vaccination discussions in the U.S. following a major measles outbreak linked to Disneyland last year.
Bettinger and her co-author looked for variations in vaccination rates by location and type of school — and found pockets of low vaccination, including the North Shore.
Private, non-religious schools had vaccination rates about 10 per cent lower than public schools, they found. (Religious private schools were not statistically different from public schools.)
One Waldorf school had such a low rate of vaccination, it had to be excluded from the analysis.
By location, Richmond schools had the highest vaccination rates of any local health area in the study, with more than 90 per cent of kids fully vaccinated.
Other areas were compared to the bar set by Richmond:
• West Vancouver and Bowen Island — 30 per cent below Richmond rates.
• North Vancouver — 20 per cent below Richmond.
• Vancouver Downtown Eastside — 12 per cent below Richmond.
• Vancouver Westside — 10 per cent below Richmond.
(The study did not provide absolute vaccination rates for schools in these areas, only their performance relative to Richmond.)
Vancouver Coastal Health says one reason Richmond's rates are so high is the strong working relationship there between family doctors and public health officials.
"They not only immunize young children but they also report their records to public health," said the health authority's Dr. Meena Dawar