Regular readers know that I lived in Chicago for three years in the late 1990s. Indeed, Chicago is probably my favorite city in the world, and my years there count as three of the happiest years of my life. I lived in a cool neighborhood near DePaul in Lincoln Park; never again in my life am I ever likely to live in a place with such a fine mixture of residential houses, businesses, restaurants, bars, and parks. Moreover, I still have family there, which, combined with my knowledge of the city, leads me to continue to feel a connection to the city. It’s that connection that guarantees that I remain interested in the goings-on in Chicago and is also part of the reason why the yearly descent of anti-vaccine quacks on the Chicago metro area for the Autism One quackfest annoys the crap out of me.
It’s also why I’m concerned to learn that there are a number of schools with vaccination rates that are low enough that they could serve as the incubators for outbreaks of infectious disease, as this story in Sunday’s Chicago Tribune by Trine Tsouderos, Deborah L. Shelton and Joseph Germuska, entitled Low vaccination rates in some schools raise outbreak risks reports:
Clusters of children without their required vaccinations in about 200 Illinois schools are raising the chances of school-based outbreaks of serious preventable diseases such as measles and whooping cough, a Tribune analysis of state data has found.
The Tribune found that the number of public and private schools with immunization rates below 90 percent — a protection level the state recommends in order to prevent epidemics — has grown dramatically in recent years for each vaccine.
For example, in 2003, 31 schools fell below 90 percent for measles vaccinations. Last year, 124 did. The number of schools below 90 percent for polio rose from 27 to 122 during the same period.
Some of these schools serve low-income students who arrive at school without proof that they are up-to-date on their immunizations, the Tribune found. Others are private schools serving middle-class and wealthy families who sometimes seek religious exemptions from vaccination requirements.
The story provides a detailed, interactive map that allows parents to look up the vaccination rates at their children’s schools. It reminds me of the same sort of data presented in an earlier article that looked at vaccination rates in California schools and provided a map listing vaccination rates in schools in southern California, but the Tribune map is more user-friendly.
One aspect of public healht that anti-vaccine activists frequently distort is high overall vaccination uptake rates. For example, the article points out that the overall vaccination rate in Illinois is still around 98%. Sounds great, right? Well, yes, it is quite good. The problem is that the number of schools with vaccination rates below 90%–and even those below 60%–have rapidly increased in number since 2003. These clusters of unvaccinated children eat away at herd immunity and provide a nidus for infection to take hold and spread among the population. Since no vaccine is 100% effective, these pockets of unvaccinated children can be a danger even to the vaccinated. Even worse, children who can’t be vaccinated, either because they are too young or have a medical condition that doesn’t permit them to be vaccinated, depend upon herd immunity to protect them. When that herd immunity wanes, they are at risk:
But scientists and public health officials say clusters of unvaccinated people across the country are weakening the herd immunity made possible through vaccines and resurrecting preventable childhood diseases that can be deadly.
“Whenever the community risk goes up, everyone tends to get affected, including people who are vaccinated,” said Saad Omer, an Emory University scientist who researches unvaccinated clusters. “Even the best vaccines are not perfect.”
Clusters of unvaccinated people are, Omer said, like patches of dry grass that, with a single match, can start a wildfire that will burn not only dry material, but sometimes wet as well. The match could be a student who returns from a trip abroad with measles or a train commuter with whooping cough.
That’s actually not a bad metaphor. How many times have I seen anti-vaccine advocates asking pro-vaccine parents why they should be worried if their children are vaccinated? They’re protected, right? Well, yes, but not all of them. The measles vaccine in the MMR, for instance, is around 90% effective. That’s pretty darned good as medical interventions go, but that means that around 10% of children vaccinated against measles will fail to develop adequate immunity to prevent infection.
There appear to be two types of clusters of unvaccinated children. One kind is due to poverty and a highly mobile population, where children show up at achool unvaccinated or without records of having been vaccinated. These children don’t have good access to medical care, and as a result many never receive recommended vaccinations. Many also don’t speak English very well, if at all, and many have parents who can’t read.
The next category have no such socioeconomic problems. These are schools where there are large numbers of parents seeking religious exemptions:
Clusters of unvaccinated students with religious exemptions are more common in private schools, the Tribune found, and such exemptions are rising. For example, religious exemptions for the measles shot grew from about 3,400 in 2000 to about 9,500 last year.
The increase reflects growing unease among some parents — mostly affluent, according to some surveys — about the safety of vaccinations, even though vaccines rarely cause serious complications and the notion that they can cause autism has been scientifically discredited.
That’s what I love about Trine Tsouderos. She doesn’t mince words. It’s quite true that the myth that vaccines cause autism has been scientifically discredited again and again and again and again. Unfortunately, it doesn’t die. It’s like a zombie in a monster flick; just when you think it’s finally been killed for good, a hand reaches out of the dirt of the grave to grab the ankle of children and infect them with measles. It’s all due to what Dr. E. M. Fine appropriate calls a “brutal, ugly logic”:
Strong herd immunity can protect infants and other vulnerable members of society from dangerous diseases, but achieving it requires people to think alike, and they don’t.
“Individuals, if they look at the world selfishly, will say: ‘I don’t want a needle to be stuck into my kid, but I want everyone else to be vaccinated,'” said Dr. Paul E.M. Fine, a community immunity expert and professor of communicable disease epidemiology at the London School of Hygiene and Tropical Medicine. “There is a brutal, ugly logic there.”
Which basically describes anti-vaccine groups like the NVIC and Generation Rescue perfectly.
In the end, the Chicago Tribune has done its readers and the citizens of the State of Illinois a great service by producing this interactive map. The anti-vaccine movement demands “informed consent” and to be given more information. In this case, I agree, although I doubt this is the kind of information that they want us to have. However, if I were a parent, I would certainly want to know the vaccination rate at any school where I was going to send my child. This is exactly the sort of information that should be available for every city, every county, and every state.