California schools' risks rise as vaccinations drop(latimes.com)
latimes.com
California schools' risks rise as vaccinations drop
http://www.latimes.com/news/local/la-me-immunization29-2009mar29,0,3148179.story
3 comments
Regardless of reason, the parent has the ultimate right to decide for his and her children. The government takes a back seat. True liberty lies in the capability to make decisions that the majority disagrees with.
Besides -- if these children do catch communicable diseases, and your children are vaccinated, what are you worried about?
Besides -- if these children do catch communicable diseases, and your children are vaccinated, what are you worried about?
Something I've never understood: If immunization prevents you getting a disease, and you are immunized, why are you worried about catching the disease from people who aren't immunized?
I'm aware the the above may be an oversimplification and someone might have a good explanation - that would be most welcome.
I'm aware the the above may be an oversimplification and someone might have a good explanation - that would be most welcome.
Two reasons:
First, no vaccine is 100% effective. You can be vaccinated for something, yet still get the disease if you're exposed consistently, or with a great intensity. Thus, the goal of most vaccinations is to achieve "herd immunity", wherein enough people within a population are vaccinated that the chance of any person being exposed to a case of the disease is low enough that even an imperfect vaccine can be considered 100% effective.
If herd immunity is not achieved, then even the best vaccines will fail to protect some percentage of the population. Outbreaks will occur, and vaccinated people will succumb; in particular, people with weakened immune systems, the elderly, and pregnant women are susceptible to diseases, even when vaccinated.
Second, for some diseases -- such as chickenpox and rubella -- incomplete immunization of a population actually results in worse epidemics, because the incomplete immunization of a population tends to shift the cases of the disease to older people. And for diseases like chickenpox and rubella, childhood infection is relatively innocuous, whereas infection as an adult can kill you.
This latter concern isn't merely hypothetical -- there was a recent example of the consequences of incomplete vaccination in Greece, in the early 1990s. Because the Greeks had only inconsistently vaccinated for rubella starting in the 60s, there was a huge outbreak of adult rubella infections in 1993, and as a result of that, there was an epidemic of rubella-related spontaneous abortions and birth defects (a condition known as congential rubella syndrome, which is a hideous disease that the rubella vaccine was arguably intended to prevent). Had the immunization rate for rubella been high enough to achieve herd immunity, this never would have happened.
First, no vaccine is 100% effective. You can be vaccinated for something, yet still get the disease if you're exposed consistently, or with a great intensity. Thus, the goal of most vaccinations is to achieve "herd immunity", wherein enough people within a population are vaccinated that the chance of any person being exposed to a case of the disease is low enough that even an imperfect vaccine can be considered 100% effective.
If herd immunity is not achieved, then even the best vaccines will fail to protect some percentage of the population. Outbreaks will occur, and vaccinated people will succumb; in particular, people with weakened immune systems, the elderly, and pregnant women are susceptible to diseases, even when vaccinated.
Second, for some diseases -- such as chickenpox and rubella -- incomplete immunization of a population actually results in worse epidemics, because the incomplete immunization of a population tends to shift the cases of the disease to older people. And for diseases like chickenpox and rubella, childhood infection is relatively innocuous, whereas infection as an adult can kill you.
This latter concern isn't merely hypothetical -- there was a recent example of the consequences of incomplete vaccination in Greece, in the early 1990s. Because the Greeks had only inconsistently vaccinated for rubella starting in the 60s, there was a huge outbreak of adult rubella infections in 1993, and as a result of that, there was an epidemic of rubella-related spontaneous abortions and birth defects (a condition known as congential rubella syndrome, which is a hideous disease that the rubella vaccine was arguably intended to prevent). Had the immunization rate for rubella been high enough to achieve herd immunity, this never would have happened.
Thanks for explaining. The first reason makes sense. The second doesn't, though. I understand that if an entire generation wasn't immunized, then that generation is susceptible when they are old (as at any age), but I don't see why, in the general case, older people would be more vulnerable.
If you only immunize 50% of each generation against a virus, then you slow the transmission rate of the virus, but you also allow the number of susceptible individuals to grow over time. Eventually, the number of susceptible individuals reaches a critical threshold, and outbreaks occur.
Because this process takes years, by the time the outbreaks begin, the average age of the un-immunized population has increased. On the other hand, if nobody is immunized, most people will acquire the virus at a young age, become naturally immune (or die), and the average age of incidence will be low.
Here's a link to a slideshow that explains the concept in greater detail (I've started it at a slide that discusses the Greek rubella outbreak, but if you want the mathematical models, go back to slide 1):
http://www.pitt.edu/~super1/lecture/lec1181/023.htm
Because this process takes years, by the time the outbreaks begin, the average age of the un-immunized population has increased. On the other hand, if nobody is immunized, most people will acquire the virus at a young age, become naturally immune (or die), and the average age of incidence will be low.
Here's a link to a slideshow that explains the concept in greater detail (I've started it at a slide that discusses the Greek rubella outbreak, but if you want the mathematical models, go back to slide 1):
http://www.pitt.edu/~super1/lecture/lec1181/023.htm
I think you're looking at the problem backwards. Some parents feel safe not giving their children shots because everybody else's children had their shots, therefore the total number of disease carriers are low.
The article states that some elementary schools are reaching a 'critical mass' of students without vaccinations that will cause outbreaks. Since most of these students tend from wealthy, affluent families, the example in the story of contracting measles from a different country, importing it here, and spreading it to the other elementary schools is a danger to all those who have not had their shots.
To answer the above question: If you're immunized, there's nothing to worry about. The problem is if you're not immunized, and your child is in a 'critical mass' set, parents may have to rethink their beliefs as the immunizations do protect against deadly diseases.
The article states that some elementary schools are reaching a 'critical mass' of students without vaccinations that will cause outbreaks. Since most of these students tend from wealthy, affluent families, the example in the story of contracting measles from a different country, importing it here, and spreading it to the other elementary schools is a danger to all those who have not had their shots.
To answer the above question: If you're immunized, there's nothing to worry about. The problem is if you're not immunized, and your child is in a 'critical mass' set, parents may have to rethink their beliefs as the immunizations do protect against deadly diseases.
I've spent much of the last 4 years of my life studying the state of the research of Autism and neurological diseases and disorders. Does Autism scare the crap out of me? Heck yeah! Did I immunize my 10 month old boy - yes. Did every member of my lab immunize their sons and daughters - yes. There's a correlation study for you - 100% of our group of researchers who are better read than 99.99% of the world on Autism and the state of Autism research immunized ALL of their children. I can't wait to be on the cover of TIME!