There have been several diaries here detailing the anti-vaccination movement, which has, on the basis of no peer-reviewed scientific data, claimed a connection between childhood vaccination and autism. Publicized by such stalwart scientists as Jenny McCarthy and Jim Carey, the claims have led to many parents electing to avoid or to amend the vaccination regimen for their children.
Many of those parents have relied on the so-called "herd immunity", which posits that if 95% of other kids are vaccinated, their unvaccinated kids are in the clear.
Well, maybe not.
More below the fold:
A new case study published in the scientific journal Pediatrics concluded, based on an examination of medical records, that children whose parents refuse vaccines are 23 times more likely to get whooping cough.
Here's the money quote from the study's leading researcher:
"This study helps dispel one of the commonly held beliefs among vaccine-refusing parents: that their children are not at risk for vaccine preventable diseases," said study lead author Jason Glanz, Ph.D., a senior scientist at Kaiser Permanente's Institute for Health Research. "It also shows that the decision to refuse immunizations could have important ramifications for the health of the entire community. Based on our analysis, we found that one in 10 additional whooping cough infections could have been prevented by immunization."
This is important news for American parents who may have been reassured by the fact that vaccination refusal rates are still well under 5% in the US, although from 1991 to 2004, refusal rates more than doubled.
I refer you to the excellent blog Respectful Insolence for an excellent summary of and commentary regarding the study.
I do not mean to imply that there is no correlation between vaccination rates and disease incidence. Indeed, there does appear to be a correlation; a negative one. In the UK, where the anti-vaccination hysteria has had a greater impact, rates are on the rise.
From an article in The Guardian in June 2006:
This month, the Health Protection Agency reported 449 cases of measles so far this year - more in just six months than the 438 reported cases in 2003. In 2005, there were only 77 reported cases.
And this is relevant because of reduced immunization rates:
A year ago MMR uptake stood at 70.8% in London and 83% for the whole of the UK.
From the Independent in February 2008, the trend continued.
As the Guardian article detailed, London had the lowest immunization rates. Again from the Independent:
There were 971 cases of measles recorded in 2007, up from 740 in 2006. Four out of five cases were in children under 15. Three quarters of cases occurred in London and the South-east.
Folks, the anti-vaccination scare, as it related to autism, is not just bad science, it is dangerous fear-mongering. And for any parent out there relying on the "herd immunity" to protect your child, don't.